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ABSTRACT Feeding behaviour traits, such as number, duration or intake per feeder visit, have been associated with feed efficiency in dairy cattle. Those traits, however, do not fully capture cows' feeding patterns throughout the day. The goal of this study was to propose a new phenotype for characterising within‐day feeding patterns and estimate its heritability and genetic correlations with dry matter intake (DMI), secreted milk energy, metabolic body weight and residual feed intake. Feeding patterns were evaluated using 4.8 million bunk visits from 1684 midlactation Holstein cows collected from 2009 to 2023 with an Insentec system. Feed efficiency traits were available from 6099 lactating Holstein cows at six research stations across the United States. Daily bunk visits were ordered, with Time 0 designated as the time of first feed delivery. Intake proportions were calculated by visit for each cow by dividing feed intake per visit by the total intake of the cow for that day. Feeding patterns were characterised by the area under the curve of cumulative feed intake proportions for each cow throughout the day. The feeding pattern phenotype per cow was defined as the average of areas under the curve across days, whereas consistency of feeding pattern was calculated as the natural logarithm of variance of daily area under the curve values. Estimates of heritability and genetic correlations were performed using Bayesian inference with an animal model, considering lactation, days in milk and cohort (trial–treatment) as fixed effects and animal as a random effect. Heritability estimates for average area under the curve and variance of daily area under the curve were 0.35 ± 0.05 and 0.16 ± 0.05, respectively. The genetic correlation between average area under the curve and secreted milk energy was −0.30 ± 0.14. Genetic correlations between average area under the curve and DMI, metabolic body weight and residual feed intake were not statistically significant. Variance of daily area under the curve was genetically correlated with DMI (0.47 ± 0.15), secreted milk energy (0.40 ± 0.17) and metabolic body weight (0.28 ± 0.13). The genetic correlation between variance of daily area under the curve and residual feed intake was not significant. Overall, we provided a reliable method to truly characterise feeding patterns in midlactation dairy cows. Feeding pattern and its consistency were heritable, indicating that a significant proportion of phenotypic variation is explained by additive genetic effects. Genetic correlation estimates indicate that cows with more consistent daily feeding patterns have lower DMI, lower secreted milk energy and lower metabolic body weight. [ABSTRACT FROM AUTHOR]

The objective of this study was to quantify the effects of supplementing early-lactation cows with a dry pure glycerol product, delivered through the automated milking system (AMS) concentrate, in the first 21 DIM on metabolic markers, milking behavior, and milk production. In 5 commercial AMS dairy herds, 389 dairy cows were randomly assigned, controlling for parity, 21 d before expected calving to 1 of 2 treatments, within farm: (1) the control group (CON) which received the standard AMS pellet (n = 213) from 1 to 150 DIM; or (2) the glycerol group (GLY), which received the treatment AMS pellet (n = 176) formulated to additionally deliver 250 as fed g/d of glycerol product from 1 to 21 DIM, followed by the standard AMS pellet from 22 to 150 DIM. Across all farms, cows were fed partial mixed rations that were similar in ingredient and nutrient composition. One prepartum blood sample and 5 postpartum blood samples were collected from each cow to determine serum nonesterified fatty acids (NEFA), blood BHB, and blood glucose concentrations. Cow BCS was recorded every 21 d from −21 to 63 DIM. Data were collected and analyzed for the treatment period (1–21 DIM) and a follow-up period (22–150 DIM). We detected no treatment effect on serum NEFA concentrations in the first week of lactation. We detected a treatment by time interaction for blood BHB and blood glucose, where GLY cows tended to have increased BHB concentrations at 5 DIM and had decreased glucose concentrations at 9 and 12 DIM. We detected an interaction of BCS with treatment on the incidence of BHB ≥1.2 mmol/L, whereby over-conditioned CON cows (BCS ≥3.5) were 3.5 times more likely to have a high BHB test than CON cows with normal prepartum BCS. During the treatment period, GLY cows had 0.1 ± 0.05 more successful milkings per day, were delivered 0.27 ± 0.05 DM kg/d more AMS concentrate, and tended to yield 0.8 ± 0.47 kg/d more milk. During the follow-up period, GLY cows had 0.1 ± 0.04 more successful milkings per day, were delivered 0.18 ± 0.06 DM kg/d more AMS concentrate, and yielded 1.5 ± 0.53 kg/d more milk than CON cows. Glycerol supplementation allowed cows to maintain better BCS, as GLY cows lost less BCS from calving to 63 DIM than CON cows. Overall, the results of this study demonstrate that supplementing pure glycerol through the AMS concentrate for the first 21 DIM can reduce BCS loss in early lactation, improve milking behavior, and increase milk yield to mid-lactation. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Intracellular AA regulate milk protein synthesis within the mammary gland by modifying mammary plasma flow (MPF) and AA transporter activity. Amino acid transporters catalyze translocation using Na+ gradient, substrate gradient (uniporters), and exchange mechanisms; further, they exhibit specificity for individual AA or groups of AA with similar side-chain properties within each transport system. Nonessential AA are actively transported through Na+-dependent transporters and, thus, are often used as intracellular currencies for EAA transport through exchange transporters. Therefore, it was hypothesized that individual EAA supplementation would compete with other EAA for shared transporters, and supplementation with Ala, Gln, and Gly would stimulate EAA transport through exchange transporters. Ten primiparous lactating dairy cows were divided into 2 groups based on milk production and were randomly assigned to treatment sequences within 2 balanced 5 × 5 Latin squares by group. Period length was 14 d. Treatments were 9-d jugular infusions of (1) saline; (2) 34.5 g of Val per day; (3) a ratio of 32.7 g of Ala to 40 g of Gln to 26.7 g of Gly per day (AQG); (4) 43 g of Lys per day; or (5) 33.5 g of Ile per day. All cows were fed a common base diet formulated to contain 15.0% CP. Infusions of Ile, Lys, or AQG did not affect milk protein or milk production; however, Val infusion decreased both. The effects of Val infusion on milk protein production appeared to be partially driven by decreased DMI. The decline in milk protein percentage indicated that milk lactose production was also affected. Additionally, Val infusion increased MPF efficiency (MPF/milk; L/L) by approximately 44%. Infusion of Val tended to decrease or decreased mammary net uptakes of Lys, Leu, Met, and total AA. Infusion of Ile tended to increase its mammary net uptakes but did not affect any other AA. Infusions of Lys and AQG did not affect any mammary net uptakes. Infusion of Val tended to decrease Phe and total NEAA mammary clearance rates. Infusion with AQG stimulated Tyr clearance rates and tended to decline system N mammary clearance rates. Ratios of branched-chain AA mammary uptake to milk protein output (U:O) did not differ from 1 for Val-infused cows, which indicated that little intramammary catabolism was occurring. Additionally, the average NEAA U:O in response to all treatments except Val was 0.70, but Val-infused cows had NEAA U:O that averaged 0.09, indicating increased synthesis within the glands. The effects of Val on mammary net clearance rates of multiple EAA support the incorporation of AA limitations in ration optimizers to prevent AA imbalances. It is possible that oversupplementation of EAA other than Val may also decrease DMI and mammary activity. Identifying efficiency apexes for each of the EAA will allow more precise diet formulation and supplementation, leading to improved production efficiency. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Blood gas analysis is a great support to the diagnostic process of critically ill patients. Its correct application to the medicine of dairy cows depends on the availability of specific reference intervals that are still difficult to find in the literature. They may vary according to the type of blood sampled, the animals' age and production stage, and climatic conditions. This study aimed at calculating the reference limits for some blood gas parameters in the blood collected from the coccygeal vessels of multiparous Holstein dairy cows. This site of sampling implies the risk of withdrawing blood of unknown origin (venous, arterial, or mixed), but it has a high practical interest for easy and quick performance and minimal animal restraint required. Data from 379 cows were used, and reference limits were produced for pH, partial pressure of carbon dioxide, bicarbonate concentration, total carbon dioxide concentration, oxygen saturation (sO 2), hemoglobin (Hb), hematocrit (Hct), base excess, glucose, Na, K, and ionized calcium (iCa). The effects of stage of lactation (5–60 vs. >60 DIM) and season of sampling (cold vs. hot) were investigated, and specific reference limits were produced for each variable and each level of the factors whenever a significant effect was detected. The pH, sO 2 , K, and iCa were not influenced by season or stage of lactation. All the other blood gas parameters were significantly affected by season of sampling, and Hb, Hct, glucose, and Na were also affected by stage of lactation. Reference limits provided in this study are specific to the site of sampling (coccygeal vessels) and the animal category considered. Further studies are needed to produce reference intervals for other blood gas parameters, cow categories, and blood types. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

The objectives of this study were to identify factors associated with the relative change in prepartum DMI (RCDMI) of 273 cows fed individually, evaluate the performance of linear models to estimate RCDMI using different classes of predictors, and characterize the implications of RCDMI to transition metabolism, health, and subsequent milk production. Two periods of interest were established. Period 1 comprised d −21 to −12 relative to calving, when DMI was stable. Period 2 comprised d −4 to −1, when average DMI was distinctly declined. The RCDMI from period 1 to 2 was calculated as a percentage value, which ranged from −75% to 15% and averaged −18.1% (± 15.0%). Season, parity, body fatness, body weight, milk production in the previous lactation and at dry-off, and length of dry period were associated with RCDMI and explained 11% of the variation in all cows, and 19% when only parous cows were considered. Performance of linear models to predict RCDMI was improved when data on rumination and physical activities and target blood metabolites were added. The adjusted R2 increased to values between 0.45 and 0.55, and selected models performed consistently in cross-validation analyses. To evaluate the implications of RCDMI, cows were ranked within parity according to RCDMI and classified into terciles as large decline (LDec), moderate decline (MDec), or small decline (SDec). By design, DMI did not differ between tercile groups in period 1 (13.3 ± 0.2 kg/d), but differed substantially in period 2 (LDec = 8.8; MDec = 11.2; SDec = 12.7 ± 0.2 kg/d), creating important differences in RCDMI among groups (LDec = −33.8; MDec = −16.2; SDec = −3.4% ± 0.8%). At enrollment, cows in the LDec and MDec groups were heavier (LDec = 788; MDec = 775; SDec = 750 ± 7 kg), and the proportion of cows with BCS >3.5 was higher in LDec (LDec = 63%; MDec = 47%; SDec = 38%). An interaction between group and time was observed for postpartum DMI, which started lower in LDec than in SDec cows, equaled by the end of transition, and inverted at wk 13 and 14 after calving. Yields of ECM were greater in LDec than in SDec cows, and both groups did not differ from MDec (LDec = 41.0; MDec = 40.3; SDec = 39.0 ± 0.5 kg/d). The LDec cows had decreased energy balance and greater concentrations of nonesterified fatty acids, β-hydroxybutyrate, and aspartate aminotransferase in serum, and greater glutathione peroxidase activity in plasma than SDec cows. Larger declines in prepartum DMI were also associated with increased risk for postpartum disease, although the associations were only weak to moderate. In conclusion, a large decline in prepartum DMI of cows fed ad libitum was associated with important adjustments in the energy metabolism and antioxidants activities, and greater milk production in the subsequent lactation. These findings indicate that feed intake decline close to parturition is likely a normal response to physiological adaptations at the onset of lactation when cows are fed ad libitum. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

The objectives of this study were to identify factors associated with prepartum DMI, evaluate the performance of linear models to estimate prepartum DMI using different classes of predictors, and investigate the consequences of different levels of prepartum DMI on transition metabolism and lactation performance. Individual feed intake of nulliparous (n = 100) and parous cows (n = 173) was measured by automatic feeding bins from d −35 to 98 relative to calving. Rumination and physical activities were monitored by wearable sensors. Blood metabolites were measured on d −21, −10, −3, 0, 3, 7, 10, 14, and 21. Body weight and BCS were assessed throughout the study. The average prepartum DMI as percentage of BW (DMIpBW) was calculated for each cow and used as dependent variable of linear models. Parity, prepartum BCS and BW, 305-d milk production in the previous lactation, milk yield at dry-off (MYDO), and the length of the dry period were associated with DMIpBW. These factors explained 41% of the variation in DMIpBW across all cows and 49% in parous cows.. Estimations of DMIpBW were improved when data on prepartum rumination and blood metabolites were added into the predictive models. In the latter, the adjusted R2 increased to values between 47% and 61%, and selected models performed consistently in a 5-fold cross-validation analysis. To evaluate the implications of DMIpBW to transition metabolism and performance, cows were ranked within parity and classified into terciles as low (LFI), moderate (MFI), or high feed intake (HFI). The mean DMI was 1.44%, 1.70%, and 1.91% ± 0.01% of BW, respectively. No differences in BW were observed in nulliparous cows, but all 3 groups of parous cows differed (LFI = 892, MFI = 849, HFI = 798 ± 8 kg). The proportion of cows with BCS >3.5 at enrollment differed among all groups, and averaged 67.4%, 55.1%, and 36.5% ± 6%, respectively. For parous cows, 305-d milk production and MYDO differed among all groups and averaged 9,808, 10,457, and 11,182 ± 233 kg, and 18.1, 23.1, and 26.2 ± 1 kg/d, respectively. After calving, DMI (LFI = 20.9, MFI = 21.9, and HFI = 22.1 ± 0.2 kg/d) and milk yield (LFI = 36.7, MFI = 38.2, and HFI = 38.3 ± 0.4 kg/d) was lower in LFI cows compared with the other 2 groups. Postpartum energy balance differed among all groups and averaged −2.79, −1.63, and −0.66 ± 0.3 Mcal/d for LFI, MFI, and HFI, respectively. During the transition period, LFI cows had higher serum concentrations of nonesterified fatty acids, BHB, Cl (prepartum only), and aspartate aminotransferase (AST; postpartum only), and lower serum concentrations of cholesterol, P, glutamate dehydrogenase, gamma-glutamyl transferase (prepartum only), AST (prepartum only), urea (parous only), and superoxide dismutase activity (parous only). In conclusion, a low level of prepartum DMI was associated with fatter and heavier cows, lower milk production in previous lactation, important adjustments in energy metabolism during the transition period, and moderate losses in DMI and milk yield in the subsequent lactation. Moreover, the inclusion of prepartum rumination activity and target blood metabolites into predictive models improved the estimations of prepartum DMI. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

A customized voluntary waiting period (VWP) before first insemination was tested in 18 commercial dairy herds in Sweden to assess milk production, fertility, and health in primiparous cows expected to be suited for extended VWP. Cow selection for extended VWP was based on 3 criteria in early lactation: (1) the 10% of cows with highest genomic persistency index, (2) cows with a difficult calving or disease during the first month of lactation, and (3) cows with higher yield during d 4 to 33 after calving than the herd average for primiparous cows. Cows meeting at least one of these criteria were randomly assigned to either treatment with an extended VWP of at least 175 d (ExtExt; n = 174, calving interval [CInt] = 16.3 mo) or treatment with a conventional VWP of a maximum of 100 d; (ExtConv; n = 173, CInt = 12.4 mo). Cows not meeting any of the criteria were assigned to the conventional VWP treatment (ConvConv; n = 183, CInt = 12.0 mo). We found no differences in milk yield per day in the CInt between treatments, although 305-d and whole-lactation (WL) milk yields were higher for ExtExt cows (10,371 and 13,803 kg) than ExtConv cows (9,812 and 10,257 kg). Milk yield at the last test milking before dry-off was lower in ExtExt compared with ExtConv cows (24.9 vs. 28.3 kg), but the results showed no difference in dry period length between the treatments. Regarding reproductive performance, the ExtExt cows had a higher first service conception rate (FSCR; 60% vs. 45%) and lower number of inseminations per conception (NINS; 1.67 vs. 2.19), compared with the ExtConv cows. As expected, ConvConv cows had the lowest milk yield (305-d, WL, and per day) in the CInt; however, FSCR and NINS did not differ between ConvConv cows and cows in the other 2 VWP treatments. Disease incidence was higher for cows in the ExtConv compared with the ConvConv treatment, but there was no difference between ExtExt and the 2 other VWP treatments. Further, no difference in the proportion of cows with good udder health or culling rate was detected between any of the treatments, though due to low prevalence, the study lacked power to draw major conclusions on these results. Thus, prolonging VWP for suitable primiparous cows can produce benefits such as improved fertility in the form of higher FSCR and lower NINS, as well as lower dry-off yield, without compromising milk yield or prolonging dry period length. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Artificial insemination and embryo transfer (ET) are important in the reproduction of dairy cows. The conception rate after AI or ET is an essential indicator when selecting appropriate breeding methods. However, information on the environmental factors affecting ET conception rate when compared with AI is limited. We aimed to investigate environmental factors affecting ET conception rate and characterize the differences in environmental factors between AI and ET. Records of the first AI (n = 1,870,143) and ET (n = 29,922) from Holstein nulliparous, primiparous, and multiparous cows in Hokkaido, Japan, were analyzed using separate multivariable logistic regression models. For each breeding method, we grouped primiparous and multiparous cows according to milk yield at peak lactation (PY; <25, 25–30, 30–35, or ≥35 kg in primiparous; <40, 40–45, 45–50, or ≥50 kg in multiparous) and the interval from calving to first AI or to first ET (CFI and CFT, respectively; <60, 60–79, 80–99, or ≥100 d) to evaluate the effects of PY and CFI or CFT on conception rate. The AI conception rate decreased with increasing PY in primiparous and multiparous cows, whereas ET conception rate did not decrease significantly. Additionally, the ET conception rate did not decrease even in primiparous and multiparous cows slightly earlier than 60 d in CFI/CFT compared with those in CFI/CFT after 60 d, which differed from the AI conception rate. Collectively, breeding by ET leads to the avoidance of negative effects of high milk yield and calving on the conception rate, indicating that cows are fertile by ET within 60 d after calving. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

High-yielding dairy cows encounter metabolic challenges in early lactation. Typically, BHB, measured at a specific time point, is employed to diagnose the metabolic status of cows based on a predetermined threshold. However, in early lactation, BHB is highly dynamic, with high interindividual variability in its time profile. This could limit the effectiveness of the single measurement and threshold-based diagnosis and could contribute to the disparities in reports linking metabolic status with productive and reproductive outcomes. This research examines the trajectories of BHB to unveil intercow variations and identify latent metabolic groups. We compiled a dataset from 2 observational studies involving a total of 195 lactations from multiparous Holstein Friesian cows. The dataset encompasses measurements of BHB, nonesterified fatty acids (NEFA), and insulin from blood samples collected at 3, 6, 9, and 21 DIM, along with weekly determinations of milk composition and fatty acids (FA) proportions in milk fat. In both experiments, milk yield (MY) and feed intake were recorded daily during the first month of lactation. We explored interindividual and intraindividual variations in metabolic responses using the trajectories of blood BHB and evaluated the presence of distinct metabolic groups based on such variations. For this purpose, we employed the growth mixture model, a trajectory clustering technique. Our findings unveil novel insights into the diverse metabolic responses among cows, encompassing both trajectory patterns and the magnitude of blood BHB concentrations. Specifically, we identified 3 latent metabolic groups: the quickly increasing BHB (QuiBHB) cluster (≈10%) exhibited a higher initial BHB concentration than other clusters, peaked on d 9 (average maximum BHB of 2.4 m M) and then declined by d 21; the slowly increasing BHB (SloBHB) cluster (≈23%) started with a lower BHB concentration, gradually increased until d 9, and reached the highest BHB concentration at d 21 (1.6 m M serum BHB at the end of the experimental period); and the low BHB (LoBHB) cluster (≈67%) began with the lowest serum BHB concentration (serum BHB <0.75 m M) and remained relatively stable throughout the sampling period. Notably, the 3 metabolic groups exhibited significant physiological disparities, which were evident in blood NEFA and insulin concentrations. The QuiBHB and SloBHB cows exhibited higher NEFA and lower insulin concentrations as compared with the LoBHB cows. Interestingly, these metabolic differences extended to MY and DMI during the first month of lactation. The elevated BHB concentrations observed in QuiBHB cows were linked with lower DMI and MY as compared with SloBHB and LoBHB cows. Accordingly, these animals were considered metabolically impaired. Conversely, SloBHB cows displayed higher MY along with increased DMI, and thus the elevated BHB might be indicative of an adaptive response for these cows. The QuiBHB cows also displayed higher proportions of UFA, MUFA, and total C18:1 FA in milk during the first week of lactation. Prediction of the QuiBHB cows using these FA and test day variables resulted in moderate predictive accuracy (area under the receiver operating characteristic curve >0.7). Given the limited sample size for the development of prediction models and the variation in DIM among samples in the same week, the result is indicative of the predictive potential of the model and room for model optimization. In summary, distinct metabolic groups of cows could be identified based on the trajectories of blood BHB in early lactation. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Breeding animals able to effectively respond to stress could be a long-term, sustainable, and affordable strategy to improve resilience and welfare in livestock systems. In the present study, the concentrations of 29 plasma biomarkers were used as candidate endophenotypes for metabolic stress response in single-SNP, gene- and haplotype-based GWAS using 739 healthy lactating Italian Holstein cows and 88,271 variants. Significant genetic associations were found in all the 3 GWAS approaches for plasma γ-glutamyl transferase concentration on BTA17, for paraoxonase on BTA4, and for alkaline phosphatase and zinc on BTA2. On these chromosomes, single-SNP and gene-based chromosome-wide association studies were performed, confirming GWAS findings. The signals identified for paraoxonase, γ-glutamyl transferase, and alkaline phosphatase were in proximity to the genes coding for them. The heritability of these 4 biomarkers ranged from moderate to high (from 0.39 to 0.54). Plasma biomarkers are known to undergo large changes in concentration during metabolic stress in the transition period, with an interindividual variability in the rate of change and recovery time. Genetics may account in part for these differences. To assess this, we studied a subset of 139 periparturient cows homozygous at 3 SNPs known to be respectively associated with concentration of plasma ceruloplasmin, paraoxonase, and γ-glutamyl transferase. We compared the immune-metabolic profile measured in plasma at −7, +5, and +30 d relative to calving between groups of opposite homozygotes. A significant effect of the genotype was found on paraoxonase and γ-glutamyl transferase plasma concentration at all the 3 time points. No evidence for genotype effect was detected for ceruloplasmin. Understanding the genetic control underlying metabolic stress response may suggest new approaches to foster resilience in dairy cows. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

With the rapid development of animal phenomics and deep phenotyping, we can obtain thousands of traditional (but also molecular) phenotypes per individual. However, there is still a lack of exploration regarding how to handle this huge amount of data in the context of animal breeding, presenting a challenge that we are likely to encounter more and more in the future. This study aimed to (1) explore the use of the mega-scale linear mixed model (MegaLMM), a factor model-based approach that is able to simultaneously estimate (co)variance components and genetic parameters in the context of thousands of milk traits, hereafter called thousand-trait (TT) models; (2) compare the phenotype values and genomic breeding value (u) predictions for focal traits (i.e., traits that are targeted for prediction, compared with secondary traits that are helping to evaluate), from single-trait (ST) and TT models, respectively; (3) propose a new approximate method of GEBV (U) prediction with TT models and MegaLMM. We used a total of 3,421 milk mid-infrared (MIR) spectra wavepoints (called secondary traits) and 3 focal traits (average fat percentage [AFP], average methane production [ACH4], and average SCS [ASCS]) collected on 3,302 first-parity Holstein cows. The 3,421 milk MIR wavepoint traits were composed of 311 wavepoints in 11 classes (months in lactation). Genotyping information of 564,439 SNPs was available for all animals and was used to calculate the genomic relationship matrix. The MegaLMM was implemented in the framework of the Bayesian sparse factor model and solved through Gibbs sampling (Markov chain Monte Carlo). The heritabilities of the studied 3,421 milk MIR wavepoints gradually increased and then decreased in units of 311 wavepoints throughout the lactation. The genetic and phenotypic correlations between the first 311 wavepoints and the other 3,110 wavepoints were low. The accuracies of phenotype predictions from the ST model were lower than those from the TT model for AFP (0.51 vs. 0.93), ACH4 (0.30 vs. 0.86), and ASCS (0.14 vs. 0.33). The same trend was observed for the accuracies of u predictions for AFP (0.59 vs. 0.86), ACH4 (0.47 vs. 0.78), and ASCS (0.39 vs. 0.59). The average correlation between U predicted from the TT model and the new approximate method was 0.90. The new approximate method used for estimating U in MegaLMM will enhance the suitability of MegaLMM for applications in animal breeding. This study conducted an initial investigation into the application of thousands of traits in animal breeding and showed that the TT model is beneficial for the prediction of focal traits (phenotype and breeding values), especially for difficult-to-measure traits (e.g., ACH4). The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [Display omitted] [ABSTRACT FROM AUTHOR]

Extending the voluntary waiting period (VWP) for insemination in dairy cows is of interest as a strategy to reduce the frequency of calving events and inseminate at a moment with fewer fertility problems. Little is known about the calves born from dams with a different VWP followed by a different calving interval (CInt). The objective of the current study was to identify the effect of dam's CInt on body condition, metabolic status, and milk production of their offspring from birth until 100 DIM of the offspring's first lactation. Holstein-Friesian dairy cows (n = 154, 41 primiparous, 113 multiparous) were blocked according to parity, milk yield, and SCC and randomly assigned to a VWP of 50, 125, or 200 d. Female calves (n = 62) from cows with different CInt were monitored from birth until their first calving event as heifer. Certain dams were not successfully inseminated soon after the planned VWP, resulting in differences between the intended VWP and the actual CInt. Calves were regrouped according to their dam's actual CInt (CInt_1: 324–408 d; CInt_2: 409–468 d; CInt_3: 469–586 d). The dam's CInt did not affect calf birth weight. From birth to weaning, the calves born to dams in CInt_1 had a higher plasma nonesterified fatty acids (NEFA) concentration (0.34 mmol/L; CI: 0.30, 0.37) than CInt_2 (0.28 mmol/L; CI: 0.26, 0.31) and CInt_3 (0.26 mmol/L; CI: 0.24, 0.29) calves. Calves born to dams with a shorter CInt (CInt_1) had greater IgG and IgM against keyhole limpet hemocyanin (KLH) than CInt_3 (IgG: 6.05 ± 0.30 vs. 4.64 ± 0.30; IgM: 6.45 ± 0.17 vs. 5.89 ± 0.16, respectively; mean ± SE) before weaning. After weaning till calving, CInt_1 calves tended to have greater plasma NEFA concentration than CInt_3-calves. During the first 100 DIM, a longer CInt of the dams resulted in lower plasma IGF_1 (CInt_2), lower milk lactose (CInt_3), and lower fat- and protein-corrected milk (FPCM; CInt_2) in offspring, compared with shorter CInt of the dams (CInt_1). Collectively, a longer CInt in dams did not affect birth weight of their calves or BW during the weaning or rearing phase. From birth till weaning, a longer CInt in dams resulted in less anti-KLH IgG and lower plasma NEFA concentration in plasma of the calves. During the first lactation of their offspring, a longer CInt in dams can result in a lower plasma IGF_1 and FPCM during the first 100 DIM, although effects were not present in all CInt categories. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of puerperal metritis (PM) diagnosed and treated during the early postpartum period of the first lactation on transition cow health, milk production, reproduction, and culling of dairy cows in their second lactation. Diagnosis of PM was based on fetid watery red-brown uterine discharge and rectal temperature above 39.5°C. Two farms were enrolled in this retrospective observational cohort study (farms A and B). In both farms, the following diseases were recorded during the first 30 DIM in lactation 1 and 2: clinical hypocalcemia (CH), retained fetal membrane (RFM), PM, hyperketonemia (KET), left displaced abomasum (LDA), and clinical mastitis (MAST). Statistical analyses were performed using SPSS for Windows separately for each farm. Linear and logistic regression models were used for continuous (e.g., milk yield) and binary (e.g., disease, pregnancy per AI, pregnancy loss) outcomes, respectively. Cox proportional hazard regression models were calculated to model the time to event outcomes for culling or death during the first 60 DIM and for pregnancy within 250 d of the second lactation. The initial models contained the following variables: year of calving, month of calving, calving ease, stillbirth, twins, days open in lactation 1, 305-d milk yield in lactation 1, PM in lactation 1, and PM in lactation 2 as explanatory variables. A total of 4,834 cows (farm A) and 4,238 cows (farm B) in the second lactation were considered for statistical analyses. On farm A, the incidence of PM in lactations 1 and 2 were 20.1% and 11.2%, respectively. On farm B, the incidence of PM in lactations 1 and 2 were 14.4% and 8.5%, respectively. On both farms, cows with PM in their first lactation had greater odds for RFM and PM in their second lactation, whereas there was no association of PM in the first lactation with any other nonuterine diseases (i.e., CH, KET, LDA, and MAST) in the second lactation. Cows with PM in lactation 2 had reduced milk yield. The reduction in milk yield in second lactation was greater for cows that already experienced PM in lactation 1. On farm A, cows with PM in their first lactation had a greater hazard for culling within 60 DIM of the second lactation; however, the same association was not present on farm B. Cows with PM in lactation 1 had reduced pregnancy per AI at first service in the second lactation only on farm B. Cows with PM in lactation 2 had reduced pregnancy per AI at first service in the second lactation on both farms. Pregnancy loss in lactation 2 was only associated with PM in lactation 2 but not with PM in lactation 1. On both farms, cows had a reduced hazard for pregnancy in their second lactation within 250 DIM when they experienced PM in either lactation. In conclusion, PM in the first lactation had long-lasting negative consequences (i.e., risk of uterine disease and lower reproductive performance) for cows in their next lactation. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Few studies have examined the N kinetics of individual feeds with stable isotope tracing. We hypothesized that N partitioning to milk and excreta pools as well as the rates of the processes that drive this partitioning would differ for alfalfa silage, corn silage, corn grain, and soybean meal. Feed ingredients were endogenously labeled with 15N and included in 4 diets to create treatments with the same dietary composition and different labeled feed. Diets were fed to 12 late-lactation dairy cows for 4 d (96 h) and feces, urine, and milk collection proceeded during the 4 d of 15N enrichment and for 3 d (80 h) after cessation of label feeding. Nonlinear models of 15N enrichment and decay were fit to milk (MN), urine (UN), and fecal N (FN) in R with the nlme package, and feed-specific parameter estimates were compared. The estimated proportions of feed N that were excreted in feces supported our understanding that N from soybean meal and corn grain is more digestible than N from alfalfa and corn silage. Estimates for the N partitioning between milk and urine from the 2 concentrate feeds (soybean meal and corn grain) indicated that UN/MN ratios were less than or equal to 1:1, indicating either more or equal nitrogen partitioning to milk compared with urine. It is important to maintain factual accuracy in representing the results rather than implying a desired outcome unsupported by the data. In contrast, UN/MN ratios for forage feeds (corn and alfalfa silage) were >1:1, indicating more N partitioning to urine than milk. The modeled proportion of total FN that originated from feed N was 82.2%, which is in line with previous research using a similar 15N measurement timeframe. However, the proportion of urinary and MN originating from feed N was much lower (60.5% for urine, 57.9% for milk), suggesting that approximately 40% of urinary and MN directly originate from body N sources related to protein turnover. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [Display omitted] [ABSTRACT FROM AUTHOR]

This retrospective study utilized a mixed-effects logistic model analysis to investigate variables associated with the probability of pregnancy loss (PL) between days 30 and 70 in a dataset comprising 9507 pregnancies from a single cattle herd over 10 years. The model incorporated fixed-effect variables including cow breed (Holstein, Crossbred, and Brown Swiss), parity (1st, 2nd, 3rd, and 4th or more), insemination seasons, insemination number (≤3 vs >3), estrus nature (spontaneous vs synchronized), postpartum problems, sire breed (Holstein, Fleckvieh, Brown Swiss, and Montbéliarde), zygote genotypic (pure vs crossbred), days in milk (DIM) at insemination, actual 305-day milk yield, and sire conception rate. Additionally, random effects included sire (n = 129), cow (n = 3463), and production years (n = 10). The results revealed that cows inseminated with Brown Swiss sires or sires with lower initial conception rates had higher PL rates. Biparous cows, cows with lower 305-day milk yield, cows inseminated later in DIM, cows receiving the 4th or subsequent insemination, and cows inseminated during winter or autumn had lower PL rates. The estrus type and zygote genotype did not significantly impact PL. The random effects of cow, sire, and production years were estimated at 0.230, 0.054, and 0.112, respectively. In conclusion, the study findings suggested that improving management practices for high-yielding cows, cows in early lactation stages, and cows exposed to thermal stress conditions, along with utilizing Brown Swiss cows and sires with high initial conception rates per insemination, could potentially decrease overall PL rates on the farm. Nonetheless, the results did not support the use of Crossbred cows, sires from different breeds, or specific sires to mitigate PL rates on the farm. • Individual sires in a cohort of 129 sires did not influence the pregnancy loss (PL). • Cows inseminated with sires that had higher day-30 conception exhibit lower PL. • Cows that had higher 305-day milk yield exhibit a higher possibility of PL. • Biparous cows and cows that had higher DIM at insemination exhibit lower PL. • Type of estrus and genotype of the zygote did not influence the PL. [ABSTRACT FROM AUTHOR]

ABSTRACT Parasitic infections in dairy cattle reduce herd immunity, milk production, and conception rates. This leads to higher production costs, compromised animal welfare, and increased interest in extralabel drug use. The extralabel use of anthelmintics poses food safety risks for consumers since appropriate withdrawal intervals in milk have yet to be established. Although topical eprinomectin has no milk withdrawal time, more research is needed to determine the residues present in milk after subcutaneous administration. This study aimed to characterize the pharmacokinetics of injectable eprinomectin in dry dairy cows. We hypothesized that, when given at the labeled dose, eprinomectin residues in dry dairy cattle would be below the FDA milk tolerance at the onset of lactation. Plasma was collected daily from 13 mature dairy cattle for 7 days postadministration, followed by periodic samples for 90 days. After calving, milk was collected daily until 90 days. Eprinomectin concentrations were measured using HPLC‐fluorescence detection. The maximum eprinomectin concentration in plasma and milk was approximately 36 ng/mL 43 h after administration and 3 ng/mL at the onset of lactation, respectively. The low eprinomectin levels in milk collected from these lactating dairy cattle suggest that administering eprinomectin at dry‐off is unlikely to result in violative residues. However, subcutaneous eprinomectin in lactating dairy cattle would be hard to justify unless there is evidence that the approved topical formulation is clinically ineffective. [ABSTRACT FROM AUTHOR]

Simple Summary: Heat stress during pregnancy can negatively affect the intrauterine environment, compromising fetal development and resulting in long-term physiological and structural changes that impact the postnatal outcomes of the offspring. The aim of this retrospective longitudinal study was to identify how exposure to summer season at different trimesters of intrauterine development and dam parity affect postpartum disease incidence, milk production, and herd lifespan of the offspring (F1 generation) of Holstein cows. Our preliminary findings confirmed less milk production capacity and greater culling risk in offspring experiencing the summer season during the first trimester of their intrauterine development than those during later stages. Daughters born to nulliparous dams had a lower risk of dystocia and metritis, a higher risk of retained placenta, and were more likely to remain in the herd than those born to parous dams. Minimizing summer heat exposure during the early intrauterine development of offspring through implementing heat-abatement strategies may help alleviate the risk of future production losses. A suboptimal intrauterine environment during gestation may result in the programming of long-lasting structural and physiological alterations in the developing fetus, leading to health and production complications in adulthood. This observational study aimed to identify the impact of exposure to the summer season at different trimesters of gestation, dam parity, and their interaction on the postpartum disease incidence, first-lactation milk production, and herd lifespan of the offspring (F1 generation). Using a dataset collected from two commercial herds, the female offspring were categorized into three groups based on the trimester their dams experienced summer season during pregnancy: (1) first trimester (n = 2345), (2) second trimester (n = 3513), and (3) final trimester (n = 4988). The estimated 305-day milk production was lower in daughters (as a first-lactation cow) born to dams exposed to summer season during the first vs. third trimester. Summer season exposure during the first vs. third trimester resulted in the offspring that were less likely to remain in the herd (hazard ratio = 0.90; 95% CI = 0.84–0.95). Daughters of parous vs. nulliparous dams were more likely to experience dystocia and metritis but less likely to experience retained placenta. The risk of culling was higher in daughters of parous vs. nulliparous dams. Our preliminary findings suggest that the first trimester is a critical determinant of the female progeny's future productive performance and survivability. Dam parity was also identified as an influential factor affecting offspring health, as dystocia and metritis were more prevalent, and the culling risk was greater in daughters born to parous dams. [ABSTRACT FROM AUTHOR]

Simple Summary: Donkey milk has a nutritional value similar to that of human milk. Methionine (Met) is an essential amino acid for lactating animals. The addition of dietary Met can improve lactation performance in dairy cows. However, the effects of Met on lactating donkeys have not been investigated. This study investigated the effects of the addition of different concentrations of Met on the milk performance and milk metabolites of lactating donkeys. The results showed that the addition of dietary Met improved the milk yield and milk component production of donkeys as well as altering the milk metabolites. This study provides a basis for the nutritional regulation of milk synthesis and a method for improving the lactation performance of donkeys. This study investigated the effects of adding methionine (Met) in milk production and the milk and blood metabolites of lactating donkeys. Eighteen healthy multiparous donkeys in early-stage lactation were selected for this study. The donkeys were randomly divided into three groups and fed diets with different levels of Met: control group (C, Met 0 g/d), Met group I (M1, Met 5 g/d), and Met group II (M2, Met 15 g/d). The total duration of the experiment was 5 weeks. Donkey milk and blood samples were collected at the end of the experiment. The milk yield and composition, milk, and serum metabolites were analyzed. The results showed that the addition of 5 g of Met significantly increased milk yield as well as the milk composition contents of protein, fat, lactoferrin, polyunsaturated fatty acid (PFA), solids, and solids-not-fat (SNF) (p < 0.05). Significant differences in metabolites were detected among the different samples of milk (p < 0.05). The addition of Met increased the levels of milk metabolites, such as myristic acid, d-glutamine, l-aspartic acid, and LPS 16:0. A total of 753 metabolites were detected in the serum, including 17 differential metabolites between C and M1 and 48 differential metabolites between C and M2. The levels of serum metabolites, such as l-ascorbate, inositol, and l-lysine, were up-regulated by the addition of Met (p < 0.05). The above results indicated that Met increased donkey milk production and milk composition yield and improved milk metabolites by regulating serum metabolites. These results provide a foundation for improving the nutritional needs of lactating donkeys and the nutritional regulation of donkey milk synthesis. [ABSTRACT FROM AUTHOR]

Simple Summary: The need for suitable tools to measure urination behavior in the field during pastoral grazing is well recognized. The current study investigated the accuracy of a modified urine sensor (PEETER V2.0) that measures urine volume and collects a proportional urine sample from every urination event. These can then be used for analysis of the urine nitrogen concentration and an estimation of the daily urine nitrogen excretion of each cow. The findings indicate a strong and positive correlation between the actual and sensor-derived values regarding urine volume. There was also a strong and positive correlation between the samples collected by the sensor and observers regarding urine nitrogen concentration and the calculated urinary nitrogen excretion. Further analysis indicated that the nitrogen concentration of the urine sample collected by the sensor is a reasonable mean of the daily average urinary nitrogen concentration. Therefore, the sensor is a real-time tool that measures urine volume and collects a sample for analyzing and estimating the mean urinary N excretion from grazing dairy cattle. This could be useful for evaluating the impacts of various strategies, such as nutritional manipulation, on urinary nitrogen excretion in grazing systems in the field. The purpose of this research was to validate a urine sensor (Lincoln University PEETER V2.0, Canterbury, New Zealand) that records the time and volume of urination events for dairy cows in addition to collecting a proportional urine sample from all urination events. Sixteen multiparous Holstein × Jersey mid-lactating cows (101 ± 5 days in milk, 498 ± 24.2 kg body weight, 26.2 ± 3.07 kg/d milk yield; mean ± standard deviation) were allocated herbage diets ranging in protein and sodium content to generate a range of urine volumes and urine nitrogen (UN) concentrations. Total collection of individual urination events occurred during a 72-h measurement period where PEETER V2.0 sensors were attached to cows. A mixed model ANOVA using lme4 package (version 1.1-35.5) in R (version 4.3.3) were used to compare the means. The average urine event size was 2.65 ± 1.1 L for total collection by observers and 2.68 ± 1.1 L as recorded by the sensor (mean ± standard deviation; p = 0.730). The urine nitrogen concentration was 5.76 ± 1.2 g N/L for samples collected by observers and 5.85 ± 1.3 g N/L for the samples collected by the sensor (p = 0.583). The calculated UN excretion was 156 ± 45.1 g/day for direct measurements and 162 ± 40.0 g/day for the sensor (p = 0.539. Contrasts with simultaneously measured data were undertaken using Lin's Concordance Correlation Coefficient (CCC) and a Pearson correlation coefficient (r). Correlations between the actual values and sensor values were strong, with little to moderate variability in the urine volume (CCC = 0.936, r = 0.937; n = 222), UN concentration (CCC = 0.840, r = 0.837, n = 48) and total UN excretion (CCC = 0.827, r = 0.836, n = 24). Considering the findings, the PEETER V2.0 urine sensor has the potential to reliably measure urine volumes and UN concentrations for estimations of the UN excretion of dairy cattle under grazing systems. [ABSTRACT FROM AUTHOR]

Simple Summary: This study at a commercial dairy farm in Queensland, Australia, evaluated the effects of a lactic acid bacteria-based direct-fed microbial (DFM) on periparturient dairy cows. A total of 150 Holstein cows were divided into control and DFM groups, with the latter receiving a basal diet supplemented with three strains of bacteria from the genus formerly known as Lactobacillus but recently assigned to the new Lentilactobacillus and Lacticaseibacillus genera. Blood samples were collected to assess metabolic profiles, revealing higher serum glucose, NEFA, and chloride levels in the DFM cows. The DFM cows showed higher pre- and post-calving glucose levels and greater body weight. While milk production was slightly higher in DFM cows, the milk protein percentage was higher in the control cows. Overall, DFM supplementation positively influenced the cows' metabolic profiles, potentially enhancing milk production and body weight postpartum. This study was conducted at a commercial dairy farm in Queensland, Australia to evaluate the effects of feeding a lactic acid bacteria-based direct-fed microbial (DFM) during gestation on the metabolic profile of periparturient dairy cows and its effects on milk production and body weight. A total of 150 multiparous Holstein cows were randomly selected based on parity (2.3) and days in milk (130 DIM) and divided into two groups of 75 cows each (control and DFM). The control cows were assigned to a basal diet consisting of a silage-based partial mixed ration (PMR), concentrate fed in the dairy twice a day, and ad libitum pasture. The DFM group received the same basal diet supplemented with three strains of Lactobacillus top-dressed in the feed. The DFM supplementation continued during both the dry period and the subsequent lactation. A subset of 82 cows (40 control and 42 DFM) were monitored during the calving season (March to July 2022) to assess the metabolic profile and postpartum performance. Blood samples were collected during the periparturient period (−4 to −2 w prepartum, around calving, and at weeks 1, 3, and 6 postpartum) to measure the levels of metabolites, enzymes, and minerals. Overall, the serum glucose, NEFA, and chloride levels were higher, while protein and urea were lower in cows supplemented with the DFM (p < 0.005). The pre-calving levels of glucose were higher and the total bilirubin, urea, and BHB were lower in cows supplemented with DFM than in the control (p < 0.05). The post-calving levels of glucose and Mg were also higher in the DFM cows than in the control cows (p < 0.05). Average milk production at 110 DIM was significantly higher in the DFM cows compared to control cows (p = 0.03). Although the total milk production over 305 days was numerically greater in the DFM cows, the difference was not statistically significant (p = 0.3), whereas the milk protein percentage was higher in the control cows (p = 0.03). The body weight of the DFM cows was greater during the periparturient period (p = 0.001) than that of the control cows. In the DFM cows, glucose levels had a positive correlation (r = 0.16) with milk yield, at 110 DIM, while serum total protein had a positive correlation with body weight (r = 0.32) (p < 0.05). In conclusion, feeding Lactobacillus-based DFM during gestation can positively influence the metabolic profile of periparturient cows, which, in turn, may affect the milk production and body weight of postpartum dairy cows. [ABSTRACT FROM AUTHOR]

Level of dam milk production (DMP) and dam milk fat to protein ratio (DFPR), as an indicator of metabolic status in dairy cows, have been identified to be associated with productive and reproductive performance of the offspring. Yet whether the interaction of DMP by DFPR can be associated with performance of the offspring have not been studied to our knowledge. Therefore, the present study was conducted to investigate the association of the main and interactive effects of DMP and DFPR with offspring's birth weight, survival, milk yield and fertility. To this end, data of birth weight, culling rate, milk yield and reproductive variables of offspring born to lactating dams (n = 14,582) and data associated with DMP and DFPR during 305-day lactation were retrieved. Afterwards, offspring were classified in three categories of DMP, including DMP1 (dams with <10.00 × 103 kg of 305-day milk production), DMP2 (dams with ≥10.00 × 103 kg and <14.00 × 103 kg of 305-day milk production), DMP3 (dams with ≥14.00 × 103 kg of 305-day milk production), and three categories of DFPR, including DFPR1 (offspring born to dams with <1.00 FPR), DFPR2 (offspring born to dams with ≥1.00 and < 1.40 FPR) and DFPR3 (offspring born to dams with ≥1.40 FPR). Statistical analysis revealed no association of the interaction effect of DMP by DFPR with investigated variables in the offspring (P > 0.05). However, the main effect of DMP was positively associated with milk yield, but negatively associated with survival, age at first insemination and conception during nulliparity, and transgenerational improvement in milk yield in the offspring (P < 0.05). Moreover, the main effect of DFPR was positively associated with birth weight, survival and first service conception rate during nulliparity, but negatively associated with metabolic status and reproductive performance during primiparity in the offspring (P < 0.05). In conclusion, the present study did not find any interaction effect of DMP by DFPR on productive and reproductive variables in the offspring. This finding implicates the association of DMP with milk production in the offspring was regardless of DFPR. Moreover, this finding implies the association of DFPR with postpartum metabolic status and reproductive performance in the offspring was regardless of DMP. • The interaction effect of dam milk production (DMP) by dam fat to protein ratio (DFPR) was not associated with productive and reproductive performance of the offspring. • Although the main effect of DMP was positively associated with milk production of the offspring, it was negatively associated with transgenerational improvement in milk production. • The main effect of DFPR was associated with postpartum metabolic status and reproductive performance of the offspring. [ABSTRACT FROM AUTHOR]

The incorporation of modern animal models become imperative for planning breeding strategies of dairy populations. The present study was designed to compare between single-trait and multi-traits animal models in estimating genetic parameters and breeding values for some milk yield and reproductive traits of Holstein-Friesian dairy cattle. A total of 9450 records of dairy cows calved in the period between 2007 and 2018 were included in the analyses by using the datasets of the first four lactations. Mixed model methodologies have been applied through applications of restricted maximum likelihood estimation algorithms. The heritability estimates for investigated traits were found be 0.26 for lactation milk yield (LMY), 0.42 (0.45) for milk fat percentage, 0.41 (0.44) for milk protein percentage, 0.13 (0.14) for lactation length (LL), 0.14 (0.15) for age at first calving, 0.17 (0.18) for calving interval, and 0.10 (0.13) for days open as denoted by single-trait (multi-traits) models, respectively. The genetic correlations between lactation milk yield and fertility traits ranged from 0.41 to -0.74. The highest genetic correlation was found between LMY and LL which was 0.84. The Akaike Information Criteria (AIC), the model evaluation measure were estimated for both models and its values were 59245.56 and 58598.23 for single-trait model and multi-traits model, respectively. Therefore, the multi-traits model, the model with the lowest value of AIC was selected as the model of choice for model’s evaluation and preference. In conclusion, the current estimates and results indicate the possibility of genetic improvements for studied traits of Holstein-Friesian cows. Moreover, the multi-traits models are highly recommended for future analyses of complex livestock traits and for construction of selection plans. [ABSTRACT FROM AUTHOR]

Background: In developing countries goat rearing is the sustainable source of income for marginal farmers. The goat milk contains lower fat per cent (3.5%) as compared to cow (4.1%) and buffalo milk (7.4%), with smaller and homogenous fat globules. It is suitable for the persons with poor digestibility of cow milk and infants having mother milk intolerance. To improve the milk production it is important to understand the mammary gland pattern during the different phases of lactation. The present study aimed at analyzing these changes by histological and histochemical observations. The mammary gland is composed of parenchyma containing acini and stroma including the ductual system. These components change during the lactation cycle. Methods: The present study was conducted on 24 goats, eighteen in lactating stage where as six from nonlactating stage. The mammary glands were collected from local abattoir with known history of stage of lactation and divided into three groups as early lactation (2-4 weeks), mid lactation (5-6 weeks) and late lactation (> 6 weeks). The histological and histochemical studies were performed during the different stages of lactation and in non lactating stage to observe the morphological and morphometrical changes along with the presence and absence of different components. Result: The lobules of the mammary gland were polygonal, triangular, oval or elongated in shape during early lactation stage. Approximately all the alveoli observed in early lactation were filled with variable quantity of eosinophilic substance and appeared foamy, due to presence of variable size of fat vacuoles. In mid lactation the lobules became highly irregular. The long and short diameter of lobules was 1041.69 µm and 563.93 µm, respectively. The intralobular stroma was inconspicuous hence alveolar wall appeared to touch each other. In late lactation lobules became shorter in size. The large alveoli showed folded and collapsed appearance. In nonlactating stage well defined alveoli, clusters of desquamated cells were seen and degenerated alveoli were also observed. These histomorphological changes in the secretory unit of the mammary gland reflect the lactation yield and milk composition during different stages of lactation. [ABSTRACT FROM AUTHOR]

Simple Summary: In pasture-based dairy systems, supplementing the diet is crucial during periods when pasture availability is low. Field peas, which can be locally produced, offer relatively high concentrations of crude protein, along with significant energy content in the form of starch, all at a lower price. These qualities make field peas a sustainable alternative to traditional protein and energy sources such as soybean meal and corn grain. This study explored the impact of substituting traditional feeds with field peas in the concentrates of grazing dairy cows. Our findings indicate that using field peas maintains milk production and composition (protein and fat) without affecting intake or ruminal and blood parameters. This suggests that field peas are a viable alternative for feeding dairy cows, supporting consistent production under grazing conditions. This study assessed the effects of replacing soybean meal (SBM) and corn grain with field peas in the concentrate of grazing dairy cows on milk production, intake, ruminal fermentation, and blood indicators. Twelve multiparous lactating Holstein-Friesian cows were utilized in a replicated 3 × 3 Latin square design, comprising three periods and three treatments: (1) Pea-0 (Control diet): 6 kg dry matter (DM) of fresh pasture, 7.2 kg DM of grass silage, and 7 kg DM of a concentrate containing 0% pea; (2) Pea-30: Control diet with the concentrate composed of 30% pea; (3) Pea-60: Control diet with the concentrate composed of 60% pea. The effect of treatments on productive and metabolic parameters was evaluated using linear-mixed models. Pasture and total DM intake, milk production, and composition were unaffected by treatments. Despite the concentrates being isonitrogenous and isoenergetic, crude protein (CP) intake was slightly higher in Pea-30 and significantly higher in Pea-60 due to higher pasture CP content in the pasture grazed by these groups, leading to higher milk urea content, though within recommended ranges. Blood parameters showed no significant changes, except for plasma β-hydroxybutyrate, which was lowest in the Pea-60 treatment; however, all values were within ranges not indicative of subclinical ketosis. Ruminal fermentation parameters were similar across treatments. These findings support the use of field peas as a viable alternative to replace SBM and corn grain in concentrates, enabling similar milk production and composition in grazing dairy cows. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to estimate the phenotypic and genetic parameters of milk production rate (MPR) traits in Holstein cattle. The MPR, a metric for evaluating a cow's milk secretion per hour, was calculated using milk yield and milking interval data from 4760 cows. This study defined four milk yield and six MPR traits, and used the MIXED procedure to assess the effects of parity, season, and lactation stage on these traits. Significant effects of these non-genetic factors were found for both milk yield and MPR traits. Heritability estimates for milk yield and MPR traits were high, ranging from 0.25 to 0.39, while the stability of MPR had low heritability (0.04 to 0.05). This study concluded that MPR is a valuable trait for dairy breeding, providing new insights for herd management and genetic selection to improve dairy cattle production performance. Milk production rate (MPR) refers to the rate of milk secretion per hour (kg/h), calculated from the harvested milk yield and milking interval, and it is considered an appropriate measure to evaluate the production potential of cows. The objective of this study was to estimate the phenotypic and genetic parameters of milk production rate traits. In this study, the milking records of 4760 Holstein cows were collected, and four milk yield traits and six milk production rate traits were defined. The MIXED procedure was used to detect the impacts of non-genetic effects on milk yield and milk production rate traits, including parity, measured season and lactation stage. Variance and covariance components for milk yield and milk production rate traits were estimated using a univariate linear repeatability model. Parity, measurement season and lactation stage had significant effects (p < 0.01) on milk yield, milk production rate and its stability. Milk yield and milk production traits had high heritability, and ranged from 0.25 to 0.39. The stability of milk production rate had low heritability (0.04~0.05). Milk production rate is beneficial for the devolving novel trait in dairy breeding and provides new insights for herd management and genetic selection of production performance of dairy cattle. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The effects of high (2.5% of DM) versus normal dietary sodium chloride (NaCl) intake on renal urea-N kinetics and urea-N metabolism were investigated in 9 rumen-cannulated and multicatheterized lactating dairy cows in a crossover design with 21-d periods. It was hypothesized that urinary urea-N excretion would be greater, and BUN concentration lower in response to greater diuresis induced by high NaCl intake. Also, urea-N transport across ruminal and portal-drained viscera (PDV) tissues was hypothesized to be affected by dietary sodium intake. A second experiment was conducted using 8 lactating cows in a crossover design with 14-d periods to test high NaCl (2.5% of DM) versus high KCl (3.2% of DM) intake on milk yield and MUN concentrations. Experiment 1 showed that despite greater diuresis, high NaCl intake had no effect on urinary urea-N excretion or BUN concentration. The high NaCl intake did not affect rumen ammonia concentrations, total rumen VFA concentrations, ruminal venous − arterial concentration differences for ammonia, or ammonia absorption indicating that high NaCl did not adversely affect ruminal fermentation and microbial protein synthesis. High NaCl intake did not affect the total amount of urea-N transport from blood to gut, but ruminal venous − arterial concentration differences for urea-N were lower with high NaCl and ruminal extraction of arterial urea-N was numerically smaller, indicating that the ruminal epithelial urea-N transport was lower with high NaCl. Energy-corrected milk yield was greater with high NaCl (3.2 ± 1.5 kg/d); however, MUN concentrations were not affected by treatment. In experiment 2, ECM was greater with NaCl (1.4 ± 0.31 kg/d) compared with KCl (30.2 and 28.8 ± 0.91 kg ECM/d, respectively). Milk urea-N concentration was lower with KCl, suggesting a urea-N lowering effect in milk not evident with high NaCl intake. In conclusion, the present data show that dietary Na intake of 12 to 13 g/kg DM was followed by greater diuresis but did not affect urea-N excretion or BUN concentration. High NaCl intake did not affect the total amount of urea-N transfer across PDV tissues. Energy-corrected milk yield was greater with high NaCl compared with both control and feeding KCl; however, with KCl, MUN decreased. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Most trace minerals (TM) are fed above dairy cow requirements in commercial herds but their fate and effects on dairy cows have not been well documented. In this study, we evaluated the effects of feeding short-term sulfate TM above recommendations on apparent total-tract digestibility of nutrients, rumen fermentation characteristics, serum concentrations, and milk yield and composition, as well as milk, fecal, and urinary TM excretion in midlactation dairy cows. Eight multiparous Holstein cows with an average body weight (± SD) of 684 ± 29 kg at 82 ± 10 DIM in a quadruple 2 × 2 crossover design were fed a basal diet, differing in sulfate TM supplement concentrations, to provide either 0.11, 17, and 63 (control; CON) or 0.95, 114, and 123 (high trace minerals; HTM) mg of dietary Co, Mn, and Zn per kilogram of DM, respectively. Each experimental period had a 21-d adaptation to the diet, followed by a 10-d sample collection period. Feed ingredients and total feces and urine were collected during 4 consecutive d and rumen fluid was collected 0, 1, 2, 4, and 6 h relative to feeding. Milk yield was recorded daily, and milk samples were collected on 4 consecutive milkings. Ingestion of Co, Mn, and Zn was higher for the HTM group compared with the CON group by 216%, 233%, and 93%, respectively. Dry matter intake averaged 25.0 (SE = 0.6) kg/d, and apparent total-tract digestibility of major nutrients was similar between treatments. High trace minerals had no measurable effect on ruminal pH, major volatile fatty acids, and protozoa counts. Isovalerate molar proportion was 9.4% greater for the HTM group compared with the CON group. Neither milk yield (43.5 kg/d; SE = 0.8) nor milk fat and protein concentrations differed between treatments. Milk urea nitrogen concentration was significantly higher for HTM (11.7 mg/dL) compared with CON (9.7 mg/dL; SE = 0.7). Fecal excretion of Co, Mn, and Zn increased by 223%, 198%, and 75%, respectively, for the HTM group compared with the CON group. Urinary excretions of TM were marginal compared with feces, and only urinary Co and Mn were significantly higher for HTM cows than CON cows, as was similarly obtained for serum Co and Mn concentrations. Milk TM yields were not modified by treatments. In summary, short-term dietary sulfate TM supply over the recommendation did not improve cow performance but significantly increased fecal TM excretion, which could affect TM accumulation in soils where manure is applied and could potentially result in leaching into nearby watersheds. Further studies are needed to evaluate the impact of high fecal TM excretion on the environment using the One Health approach. Moreover, the effects of TM oversupply on milk production and cow health should be evaluated by long-term experiments. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Interventions targeting the gut microbiota, such as fecal microbiota transplantation, prove effective in repairing the intestinal barrier and facilitating the recovery of its function and metabolism. However, the regulatory mechanisms governing the remodeling of rumen epithelial morphology and function, rumen metabolism, and host metabolism in cows of SARA remain poorly understood. Here, we explored the changes in rumen epithelial morphology and transcriptome, rumen metabolome, and blood biochemical parameters in SARA cows following rumen content transplantation (RCT). The entire experiment consisted of 2 periods: the SARA induction period and the RCT period. During the SARA induction period, 12 ruminally cannulated lactating Holstein cows were randomly allocated into 2 groups, fed either a conventional diet (CON; n = 4; 40% concentrate, DM basis) or a high-grain diet (HG; n = 8; 60% concentrate, DM basis). Following the SARA induction period, the RCT period started. The HG cows were randomly assigned to 2 groups: the donor-recipient (DR) group and the self-recipient (SR) group. Rumen contents were entirely removed from both groups before RCT. For the DR group, cows were administered 70% rumen content from the CON cows, paired based on comparable BW; for the SR group, each cow received 70% self-derived rumen content. The results revealed no significant differences in the thicknesses of the stratum corneum, granulosum, and spinosum or basale layers, as well as the total depth of the epithelium between the SR and DR groups. All these measurements exhibited a decreasing trend and fluctuations over time after the transfer. Notably, these fluctuations tended to stabilize at 13 or 16 d after RCT in the SR group, whereas they tended to stabilize after 8 or 13 d of transfer for the DR group. Transcriptome sequencing revealed that a total of 277 differentially expressed genes (DEG) were identified between the 2 groups. Enrichment analysis showed that the DEG were significantly enriched in 11 Gene Ontology biological processes and 14 Kyoto Encyclopedia of Genes and Genomes pathways. The DEG corresponding to almost any of these 11 biological process terms and 14 pathways showed mixed up- or downregulation following RCT. Metabolomics analysis indicated that a total of 33 differential metabolites were detected between the SR and DR groups, mainly enriched in 5 key metabolic pathways, including plant polysaccharides and starch degradation, lipid metabolism, amino-sugar and nucleotide-sugar metabolism, purine metabolism, and Krebs cycle. Among them, the levels of differential metabolites associated with the degradation of plant polysaccharides and starches, metabolism of amino sugars and nucleotides, and purine metabolism pathways were significantly elevated in the DR cows. The results of blood biochemical parameters showed that the triglyceride concentration of the DR cows was increased than that of the SR cows, comparable to the level observed in the CON cows during the SARA induction period. Generally, our findings indicated that RCT facilitated the recovery of rumen epithelial morphological structure but did not promote its function recovery. Moreover, RCT enhanced rumen plant polysaccharide and starch degradation, amino-sugar and nucleotide-sugar metabolism, as well as purine metabolism. Additionally, it further promoted the recovery of plasma metabolites related to lipid metabolism. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The rumen microbiome is crucial for converting feed into absorbable nutrients used for milk synthesis, and the efficiency of this process directly affects the profitability and sustainability of the dairy industry. Recent studies have found that the rumen microbial composition explains part of the variation in feed efficiency traits, including dry matter intake, milk energy, and residual feed intake. The main goal of this study was to reveal relationships between the host genome, the rumen microbiome, and dairy cow feed efficiency using structural equation models. Our specific objectives were to (1) infer the mediation effects of the rumen microbiome on feed efficiency traits, (2) estimate the direct and total heritability of feed efficiency traits, and (3) calculate the direct and total breeding values of feed efficiency traits. Data consisted of dry matter intake, milk energy, and residual feed intake records, SNP genotype data, and 16S rRNA rumen microbial abundances from 448 mid-lactation Holstein cows from 2 research farms. We implemented structural equation models such that the host genome directly affects the phenotype (G P → P) and the rumen microbiome (G M → P), and the microbiome affects the phenotype (M → P), partially mediating the effect of the host genome on the phenotype (G → M → P). We found that 7% to 30% of microbes within the rumen microbial community had structural coefficients different from zero. We classified these microbes into 3 groups that could have different uses in dairy farming. Microbes with heritability <0.10 but significant causal effects on feed efficiency are attractive for external interventions. On the other hand, 2 groups of microbes with heritability ≥0.10, significant causal effects, and genetic covariances and causal effects with the same or opposite sign to feed efficiency are attractive for selective breeding, improving or decreasing the trait heritability and response to selection, respectively. In general, the inclusion of the different microbes in genomic models tends to decrease the trait heritability rather than increase it, ranging from −15% to +5% depending on the microbial group and phenotypic trait. Our findings provide more understanding to target rumen microbes that can be manipulated, either through selection or management interventions, in order to improve feed efficiency traits. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The objective of this study was to evaluate the effect of energy and protein in the diet on the recovery of milk ethanol stability (MES) induced by feed restriction. Twelve Holstein and Holstein × Jersey crossbred cows with an average of 146 ± 50 DIM, 575.4 ± 70 kg of BW, and 18.93 ± 5.46 kg/d of milk yield were distributed in a 3 × 3 Latin square design with 3 treatments and 3 experimental periods. Each experimental period lasted 24 d, comprising 3 phases: a 13-d adaptation phase (100E+100P), a 4-d induction phase for milk ethanol instability (50E+50P), and a 7-d recovery phase for MES (3 treatments). The 3 treatments during the recovery phase consisted of 3 diets aiming to meet the requirements of energy and protein (100E+100P), only energy (100E+50P), or only protein (50E+100P). The diet during the adaptation and induction phases was common for all cows. The energy and protein levels to meet each cow's requirements were based on the group average. Restriction of energy and protein reduced DM, CP, and total digestive nutrient intake for cows fed 100E+50P and 50E+100P. The lowest BW was observed for cows fed 50E+100P, with no difference for BCS. During the induction phase, MES was reduced by 9 percentage units. Cows fed 100E+100P recovered MES in the first days of the recovery phase, whereas 100E+50P slightly improved MES, and 50E+100P had a constant decrease in MES. Cows fed 100E+50P and 50E+100P produced, respectively, 3.6 and 5.9 kg less milk than those fed 100E+100P. The 50E+100P treatment exhibited the highest milk fat content and SCS, along with the lowest milk lactose content. Protein content was higher in the 100E+100P treatment. Cows fed 50E+100P showed higher serum albumin levels compared with those on the 100E+100P treatment, not differing from the 100E+50P treatment. We concluded that the complete recovery of MES in cows with feed restrictions is possible only by supplying both the energy and protein requirements in the cows' diet. However, restricting energy intake poses a greater limitation on MES recovery compared with restricting protein. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The aim of this study was to evaluate the effects of different anti-mycotoxin feed additives on the concentration of mycotoxins in milk, urine, and blood plasma of dairy cows fed diets artificially contaminated with mycotoxins. Secondarily, performance, total-tract apparent digestibility of nutrients, and blood parameters were evaluated. Twelve multiparous cows (165 ± 45 DIM, 557 ± 49 kg BW, and 32.1 ± 4.57 kg/d milk yield at the start of the experiment) were blocked according to parity, milk yield, and DIM and used in a 4 × 4 Latin square design experiment with 21-d periods, where the last 7 d were used for sampling and data analysis. Treatments were (1) mycotoxin group (MTX), basal diet (BD) without anti-mycotoxin feed additives; (2) hydrated sodium calcium aluminosilicate (HSCA), HSCA added to the BD at 25 g/cow per day; (3) mycotoxin deactivator (MD; Mycofix Plus, dsm-firmenich) added to the BD at 15 g/cow per day (MD15); and (4) MD added to the BD at 30 g/cow per day (MD30). Cows from all treatments were challenged with a blend of mycotoxins containing 404 μg of aflatoxin B 1 , 5,025 μg of deoxynivalenol (DON), 8,046 μg of fumonisins (FUM), 195 μg of T2 toxin (T2), and 2,034 μg of zearalenone (ZEN) added daily to the BD during the last 7 d of each period. Neither performance (milk yield and composition) nor nutrient digestibility was affected by treatments. All additives reduced aflatoxin M 1 (AFM1) concentration in milk, whereas MD15 and MD30 group had lower excretion of AFM1 in milk than HSCA. Deoxynivalenol, FUM, T2, or ZEN were not detected in milk of MD15 and MD30. Concentrations in milk of DON, FUM, T2, and ZEN were similar between MTX and HSCA. Except for AFM1, none of the analyzed mycotoxins were detected in urine of MD30 group. Comparing HSCA to MD treatments, the concentration of AFM1 was greater for HSCA, whereas MD30 was more efficient at reducing AFM1 in urine than MD15. Aflatoxin M1, DON, FUM, and ZEN were not detected in the plasma of cows fed MD30, and DON was also not detected in MD15 group. Plasma concentration of FUM was lower for MD15, similar plasma FUM concentration was reported for HSCA and MTX. Plasma concentration of ZEN was lower for MD15 than MTX and HSCA. Serum concentrations of haptoglobin and hepatic enzymes were not affected by treatments. Blood concentration of sodium was lower in HSCA compared with MD15 and MD30 groups. In conclusion, the mycotoxin deactivator proved to be effective in reducing the secretion of mycotoxins in milk, urine, and blood plasma, regardless of the dosage. This reduction was achieved without adverse effects on milk production or total-tract digestibility in cows fed multi-mycotoxin-contaminated diets over a short-term period. Greater reductions in mycotoxin secretion were observed with full dose of MD. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. At the onset of lactation in dairy cows, inflammation and oxidative stress may occur and result in a risk of pathologies and lower milk yield. To propose an innovative management strategy for cows during this period, it is essential to better understand these physiological variations. Our objective was to evaluate the metabolic, redox, and immune status of 7 primiparous and 8 multiparous Holstein cows during late gestation and the first months of lactation. Blood samples were collected between 3 wk before calving until 12 wk postpartum. Milk samples were also collected, but only at the time points after calving. The metabolic (nonesterified fatty acids [NEFA], BHB, glucose, urea, calcium) and redox (reactive oxygen metabolites [ROM], oxidative stress index [OSI], glutathione peroxidase activity, vitamin E) statuses were analyzed in plasma or erythrocytes. The expression of genes related to antioxidant functions was determined in leukocytes collected from milk. For immune status, plasma cytokine levels and the production of reactive oxygen species (ROS) in classical and regulatory neutrophils were measured in 2 whole blood ex vivo challenges. The data were analyzed using a mixed model that included the fixed effects of parity and week and their interaction. Milk yield, plasma NEFA, and BHB in wk 2 and 4 after calving were higher in multiparous cows than in primiparous cows, whereas glucose and calcium tended to be lower. Plasma ROM and OSI levels in wk 8 were higher in multiparous than in primiparous cows. Multiparous cows also displayed higher glutathione peroxidase activity in erythrocytes, and antioxidant transcription factor and superoxide dismutase-1 expression levels in milk leukocytes. Moreover, multiparous cows had higher plasma concentrations of vitamin E but lower plasma levels of cytokines CXCL10, CCL2, IL1Rα, and IFNγ. Following ex vivo whole blood stimulation with Escherichia coli , lower IL1α and TNFα levels were measured in multiparous than in primiparous cows. Intracellular ROS production by neutrophils was lower in multiparous than in primiparous cows. These results thus indicated marked physiological changes in wk 8 compared with wk 2 and 4 of lactation. These differences in the physiological status of primiparous and multiparous cows offer interesting perspectives for potential dietary strategies to prevent pathologies which take account of parity and week relative to calving. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Our objectives were to compare the efficacy of ketoprofen or ceftiofur for treatment of metritis in dairy cows considering subsequent health, production, and reproduction. Cows from 2 commercial dairy farms in Ontario, Canada were examined with a Metricheck device 3 times per week from 2 to 14 DIM. Cows with metritis (fetid vaginal discharge; n = 193) were blocked by parity and fever (rectal temperature ≥39.5°C or <39.5°C) and within each block per farm, randomly assigned to receive 3 mg/kg BW of ketoprofen (KET) or 2.2 mg/kg of ceftiofur hydrochloride (CEF), once a day for 3 d. Day of enrollment was considered study d 0. Rectal temperature and attitude were evaluated in cows with metritis on study d 0, 3, 4, 7, 10, and 13, and vaginal discharge was evaluated on study d 4, 7, 10, and 13. Body condition was scored at enrollment and at 35 DIM, and serum concentration of haptoglobin was measured at d 0, 2, 4, and 7. Cows with rectal temperature ≥39.5°C or a depressed attitude on d 3 were classified as clinical failure and received treatment with ceftiofur for 3 d (KET), or 2 additional days (CEF), to a maximum of 5 d of treatment with ceftiofur. At 35 ± 3 DIM cows were examined for uterine involution via transrectal palpation, purulent vaginal discharge (PVD) via Metricheck, and endometritis via endometrial cytology. Time to onset of cyclicity was assessed by serum progesterone (P4) measurements at 28, 42, and 56 DIM. Contemporary cows from the same farms without metritis (NOMET; n = 1,043) were used for comparison. Data were analyzed with mixed linear or logistic regression or Cox's proportional hazard models, including herd as a random effect. The proportion of clinical resolution of metritis on d 3 (96% vs. 92%), of cows with fever (from d 3 to d 13 after enrollment) or fetid discharge (from d 4 to d 13 after enrollment), and the number of medical treatments (3.1 vs. 3.3) were not different between CEF and KET, respectively. Cows in KET received fewer antibiotic treatments than cows in CEF (0.3 vs. 3.1). Uterine involution, prevalence of PVD (50% vs. 47%) and subclinical endometritis (6.6% vs. 4.3%), and proportion of cyclic cows (82% vs. 86%) did not differ between CEF and KET. Cows in KET had greater serum haptoglobin concentration from d 2 to 7 after enrollment. The incidence of mastitis, lameness, or displaced abomasum to 60 DIM and subclinical ketosis to 21 DIM did not differ among CEF, KET, and NOMET. There were no differences in median time to first AI (CEF = 68 d, 95% CI: 65–70; KET = 69 d, 95% CI: 68–72; NOMET = 69 d, 95% CI: 68–70), median time to pregnancy (CEF = 118 d, 95% CI: 92–145; KET = 113 d, 95% CI: 90–135; NOMET = 105 d, 95% CI: 101–109), pregnancy at first AI at 33 d after insemination (CEF = 42%; KET = 41%; NOMET = 41%), pregnancy loss after first AI (CEF = 8%; KET = 11%; NOMET = 8%), hazard of pregnancy, or hazard of culling up to 300 DIM. Milk yield was not different between CEF and KET during the first 10 wk, but was lesser in KET at wk 2 and 4 and CEF at wk 2, 4, and 6 than in NOMET. In this pilot-scale study, given early detection, we did not detect differences in subsequent health, milk yield, or reproductive performance in cows with metritis initially treated for 3 d with CEF or KET. Additional, larger studies are warranted. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Early lactation is a critical period for dairy cows, as energy requirements rapidly increase with the onset of lactation; however, early-lactation DMI in pasture-based systems are under measured. The objectives of this study were (1) to measure and profile total DMI (TDMI) and animal performance of dairy cows during early lactation in a pasture-based system, (2) to investigate early-lactation energy balance in pasture-based systems, and (3) to examine production efficiencies, including TDMI and milk solids production per 100 kg of BW. Eighty spring-calving dairy cows were allocated to a grazing group as they calved over a 2-yr period (2021 and 2022). Cows were offered a daily herbage allowance to achieve a postgrazing sward height of 4 cm, with silage supplementation when necessary due to inclement weather. Total DMI was measured using the n-alkane technique over a 12-wk period from February 1, 2021, to April 23, 2022. Total DMI and daily milk yield were significantly affected by parity with both variables being greatest for third-parity animals (17.7 kg of DM and 26.3 kg/cow per day, respectively), lowest for first parity (13.2 kg of DM and 19.6 kg/cow per day, respectively) and intermediate for second-parity animals (16.8 kg of DM and 24.1 kg/cow per day, respectively). Peak TDMI was reached on wk 10 for first-parity animals (14.6 kg of DM), wk 11 for second parity animals (19.3 kg of DM) and wk 12 for third-parity animals (19.9 kg of DM). Parity also had a significant effect on unité fouragère lait (UFL; feed units for milk) feed balance as first-parity animals experienced a greater degree of negative energy balance (−3.2 UFL) compared with second- and third-parity animals (−2.3 UFL). Breed and parity had an effect on production efficiencies during the first 12 wk of lactation as Jersey × Holstein Friesian cows had greater TDMI/100 kg of BW and milk solids/100 kg of BW compared with Holstein Friesian cows. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The study investigated the effects of dietary protein level and the inclusion of hydroponic barley sprouts (HB) on lactation performance, blood biochemistry and N use efficiency in mid-lactation dairy cows. Treatments were arranged in a 2 × 2 factorial design with 2 CP levels (16.8% and 15.5% of DM), with HB (4.8% of DM, replacing 4.3% of alfalfa hay and 0.5% of distillers dried grains with solubles [DDGS]) or without HB. Forty-eight multiparous Holstein dairy cows (146 ± 15 DIM, 40 ± 5 kg/d of milk) were randomly allocated to 1 of 4 diets: high-protein diet (16.8% CP, HP), HP diet with HB (HP+HB), low-protein diet (15.5% CP, LP), or LP diet with HB (LP+HB). An interaction between CP × HB on DMI was detected, with DMI being unaffected by HB inclusion in cows fed the high-protein diets, but was lower in cows fed HB when the low-protein diet was fed. A CP × HB interaction was also observed on milk and milk protein yield, which was higher in cows fed HB with HP, but not LP. Inclusion of HB also tended to reduce milk fat content, and feeding HP resulted in a higher milk protein and MUN content, but lower milk lactose content. Feed efficiency was increased by feeding HP or HB diets, whereas N use efficiency was higher for cows fed LP or HB diets. There was an interaction on the apparent total-tract digestibility of DM and CP, which was higher when HB was fed along with HP, but reduced when fed with LP, whereas the digestibility of ADF was increased by feeding low-protein diets. In conclusion, feeding a low-protein diet had no adverse effect on cow performance, while feeding HB improved milk and milk component yield, and N efficiency when fed with a high-CP diet, but compromised cow performance with a low-CP diet. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Omitting or shortening the dry period may result in a fairly constant ration throughout the transition period of dairy cows, reducing the need for adaptation of cow metabolism and rumen function to a new lactation. The objective of this study was to determine the effect of dry period length (DP) on rumen adaptation and cow metabolic state during the transition period. Twelve pregnant, rumen-cannulated Holstein Friesian dairy cows at the end of their first lactation were assigned to 1 of 3 treatments: a conventional (60 d), short (30 d), or no dry period (0 d). At dry-off, cows received a dry-cow ration until calving. Lactating cows received a lactation ration. Cows were monitored from 8 wk before calving until 8 wk after calving for milk yield and DMI. Rumen biopsies were taken from 3 locations in the rumen at 60, 40, and 10 d before calving and 3, 7, 14, 28, and 56 d after calving to assess papillae dimensions. Blood was sampled weekly from 3 wk before until 8 wk after calving, and liver biopsies were taken at wk −2, 2, and 4 relative to calving. Prepartum, DMI, and milk yield were greater for cows with a short or no dry period, compared with cows with a conventional dry period. Postpartum, DMI was greater for cows with a short dry period compared with cows with a conventional dry period. Plasma glucose concentration was greater for cows without a dry period, compared with the other DP postpartum. Plasma concentrations of nonesterified fatty acids and BHB, and liver triglyceride content, did not differ among dry period. Rumen papillae differed in size based on biopsy location, but there was no interaction between biopsy location and the effect of DP. Rumen papillae surface area for cows managed for a 30- or 60-d dry period decreased toward calving. At 40 d prepartum, papillae surface area was greater for short and no dry period treatment compared with a conventional dry period. At 10 d prepartum, papillae surface area was greater for the no dry period treatment compared with both other treatments, and this difference was still present 3 d postpartum. Cows managed for a short dry period showed faster increase in papillae dimensions after calving compared with cows managed for a conventional dry period. From d 28 onwards, no differences in papillae surface area were observed. The faster rumen adaptation postpartum may be related to the increased DMI during the first weeks postpartum for cows managed for a short dry period. However, this did not result in improved metabolic status or milk yield. The results from the present study demonstrate that the dietary changes related to a conventional DP affected rumen papillae development, not only prepartum but also early postpartum. Further optimization of DP as well as dietary composition throughout the transition period may support cows in their adaptation to a new lactation. [ABSTRACT FROM AUTHOR]

Objective: Previous research reported that dietary addition with phytosterols improved the energy utilisation of the rumen microbiome, suggesting its potential to alleviate the negative energy balance of perinatal cows. This experiment aimed to explore the effects of feeding phytosterols on the metabolic status of perinatal cows through plasma metabolomics and faecal bacteria metabolism. Methods: Ten perinatal Holstein cows (multiparous, 2 parities) with a similar calving date were selected four weeks before calving. After 7 days for adaptation, cows were allocated to two groups (n = 5), which respectively received the basal rations supplementing commercial phytosterols at 0 and 200 mg/d during a 42-day experiment. The milk yield of each cow was recorded daily after calving. On days 1 and 42, blood and faeces samples were all collected from perinatal cows before morning feeding for analysing plasma biochemicals and metabolome, and faecal bacteria metabolism. Results: Dietary addition with phytosterols at 200 mg/d had no effects on plasma cholesterol and numerically increased milk yield by 1.82 kg/d (p>0.10) but attenuated their negative energy balance in perinatal cows as observed from the significantly decreased plasma level of β-hydroxybutyric acid (p = 0.002). Dietary addition with phytosterols significantly altered 12 and 15 metabolites (p<0.05) within the plasma and faeces of perinatal cows, respectively. Of these metabolites, 5 upregulated plasma fatty acids indicated an improved energy status (i.e., C18:1T, C14:0, C17:0, C18:0, and C16:0). Milk yield negatively correlated with plasma concentrations of ketone bodies (p = 0.035) and 5-methoxytryptamine (p = 0.039). Furthermore, dietary addition with phytosterols at 200 mg/d had no effects on fermentation characteristics and bacterial diversity of cow faeces (p>0.10) but improved potentially beneficial bacteria such as Christensenellaceae family (p<0.05) that positively correlated with feed efficiency. Conclusion: Dietary addition with phytosterols at 200 mg/d could effectively improve the energy status in perinatal cows by attenuating their negative energy balance. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate two levels of forage allowance (FA) during the prepartum period on metabolic, hormonal, productive, and reproductive variables in primiparous (P) and multiparous (M) beef cows. Six weeks before calving, 40 P and 42 M cows were assigned to two FA (native pastures) treatments until calving (day 0): High (15 kg DM/100 BW; H) and Low (5 kg DM/100 BW; L). After calving all cows were managed together. High FA cows presented greater intake than L cows, while M tended to have greater intake than P cows. Increased herbage allowance in late gestation in beef cows successfully improved forage intake and energy balance reflected in body condition score and metabolic and endocrine markers. Also, high forage allowance increased milk yield (5.4 vs 4.6 kg/d, P < 0.05) and calves daily gain rate during the first two months of age (0.88 vs 0.82 kg/d, P < 0.05) in H respect to L cows. Pregnancy rate was greater in H vs L cows (40 vs 28 %, P < 0,05). The endocrine metabolic response to higher forage allowance depended on parity, as primiparous cows showed a greater imbalance around calving. Moreover, most primiparous cows were not pregnant at the end of the breeding season, consistent with their prolonged anestrous. Multiparous cows had better productive and reproductive performance than primiparous cows, showing that growing cows have a pronounced negative energy balance reflected in most of the evaluated parameters. • Increased herbage allowance in late gestation improved forage intake, energy balance, milk yield and pregnancy rate. • The productive and reproductive response to forage allowance was lower in primiparous respect to multiparous cows. • Reproductive and productive parameters can be explained by metabolic and endocrine markers. [ABSTRACT FROM AUTHOR]

Simple Summary: A mechanical brush is currently used as a grooming tool to enhance the well-being of dairy cows and improve their overall environment. In the present study, we collected comprehensive data on the use of mechanical brushes by domestic dairy cows during the lactation, dry, and perinatal periods and the consequent effects on their lactation performance, health status, and reproductive performance. The findings of our study suggest that the frequency and duration of mechanical brush usage were significantly higher for brushes installed on the middle door than for brushes installed near the wall. Furthermore, the head was the preferred body part for grooming during the lactation and dry periods. Mechanical brush usage reduced postpartum stress in dairy cows, promoted blood circulation, improved the cleanliness of the body's surface, enhanced milk production of lactating cows, and increased the progesterone concentration of pregnant dairy cows after artificial insemination (AI). Thus, the installation of mechanical brushes at appropriate positions in dairy farms can improve the production performance of dairy cows and enhance milk yield. Intensive farming can reduce production costs and maximize animal production efficiency; however, it also causes many adverse effects on the welfare of dairy cows. A mechanical brush is an automated grooming device that promotes the grooming behavior of dairy cattle, thereby helping to alleviate stress. In the present study, we evaluated the effects of using mechanical brushes on the production performance of dairy cows by comprehensively analyzing their milk production, health status, and reproductive performance. The cows were assigned to 6 groups: 109 lactating dairy cows (brush treatment) and 105 controls (without brush treatment), 64 dry milk dairy cows (brush treatment) and 49 controls (without brush treatment), and 198 perinatal cows (brush treatment) and 65 controls (without brush treatment). We found an increasing trend in the daily utility time and usage frequency of mechanical brushes for each cow during the lactating period (7.73 ± 4.02 min/d and 2.90 ± 1.22 times/d, respectively), dry period (15.97 ± 14.16 min/d and 4.21 ± 2.91 times/d, respectively), and perinatal period (25.15 ± 19.05 min/d and 5.45 ± 3.83 times/d, respectively) (p < 0.01 and p < 0.05, respectively). The installation location of the mechanical brush significantly affected the frequency of its usage during the different periods. The head was the preferred body part for using the mechanical brush during the lactation and dry periods (59.32% and 44.54%, respectively), while the hip was the main preferred grooming part during the perinatal period (40.17%). Overall, the time, frequency, and preferred body part of dairy cows that used mechanical brushes varied across different physiological stages. Additionally, mechanical brush use in lactating and dry dairy cows significantly improved cleanliness of the body's surface (p < 0.05) and enhanced milk production of lactating cows (p < 0.01), particularly for cows with four and five parities. Thus, the use of mechanical brushes could improve the production performance of dairy cows and enhance sustainability of large-scale farms. [ABSTRACT FROM AUTHOR]

Sub-acute ruminal acidosis (SARA) is subclinical form of acidosis in ruminants. Haemato-biochemical investigation of the dairy herds may be helpful for the preliminary diagnosis of SARA in dairy cattle. A cross-sectional study on dairy cows maintained in various dairy farms in and around Shivamogga on different feeding patterns to determine the risk factors associated with SARA was undertaken. The presence of SARA in dairy cows was identified by measuring pH of rumen liquor falling within a range of 5.2 to 5.9. A total of 102 dairy cows were screened for SARA and the prevalence was found to be 19.61 per cent. Haematological parameters viz., Haemoglobin, packed cell volume (PCV), Total erythrocyte count (TEC) and Total leukocyte count (TLC) along with biochemical parameters namely Gamma glutamyl transferase (GGT), Aspartate amino transferase (AST), Total protein (TP), Glucose, Calcium (Ca), Phosphorous (P) were estimated from the blood collected from cows positive and cows negative for SARA. The present study revealed a considerable percentage of prevalence of SARA is prevailing in dairy cows in and around Shivamogga. The SARA positive cows showed higher Haemoglobin, PCV and TEC values than SARA negative cows indicating haemoconcentration. The SARA positive cows had significantly higher GGT values than normal range indicating liver damage. [ABSTRACT FROM AUTHOR]

This study aimed to investigate whether heat stress, as defined by the temperature-humidity index (THI) during the close-up dry period, had any impact on the productive performance, fertility, and immunometabolic blood indices of dairy cows in the subsequent lactation. Lactation performance was associated with increasing THI values on − 21, − 14, and − 7 d before calving resulting in decreased milk yield by about 2.30, 2.60, and 2.90 kg, respectively. The THI on the − 7 d before the calving was negatively associated with fertility parameters such as delayed first estrus postpartum, an elongated calving interval by approximately 32 d, a higher number of services per conception by 1.00, and an elongated artificial insemination service period, days open, and inter-calving period by about 20, 52, and 52 d, respectively. The study found that the immunometabolic blood indices were associated with increasing THI values during the close-up dry period. The study showed that exposing dairy cows to close-up dry period heat stress had negative consequences on performance, fertility, and immunometabolic blood indices in the subsequent lactation. Therefore, it is recommended that herd management and barn microclimate changes be implemented earlier, starting from the late dry period, to mitigate the negative impact of heat stress. [ABSTRACT FROM AUTHOR]

Background: The application of novel technologies is now widely used to assist in making optimal decisions. This study aimed to evaluate the performance of linear discriminant analysis (LDA) and flexible discriminant analysis (FDA) in classifying and predicting Friesian cattle's milk production into low ( 4500 kg), medium (4500–7500 kg), and high ( 7500 kg) categories. A total of 3793 lactation records from cows calved between 2009 and 2020 were collected to examine some predictors such as age at first calving (AFC), lactation order (LO), days open (DO), days in milk (DIM), dry period (DP), calving season (CFS), 305-day milk yield (305-MY), calving interval (CI), and total breeding per conception (TBRD). Results: The comparison between LDA and FDA models was based on the significance of coefficients, total accuracy, sensitivity, precision, and F1-score. The LDA results revealed that DIM and 305-MY were the significant (P < 0.001) contributors for data classification, while the FDA was a lactation order. Classification accuracy results showed that the FDA model performed better than the LDA model in expressing accuracies of correctly classified cases as well as overall classification accuracy of milk yield. The FDA model outperformed LDA in both accuracy and F1-score. It achieved an accuracy of 82% compared to LDA's 71%. Similarly, the F1-score improved from a range of 0.667 to 0.79 for LDA to a higher range of 0.81 to 0.83 for FDA. Conclusion: The findings of this study demonstrated that FDA was more resistant than LDA in case of assumption violations. Furthermore, the current study showed the feasibility and efficacy of LDA and FDA in interpreting and predicting livestock datasets. [ABSTRACT FROM AUTHOR]

The paper was to investigate the effects of sunflower straw replacing corn stover on the digestive performance, lactation performance, rumen fermentation indexes, and serum biochemical indexes of dairy cows. Eighty Chinese Holstein cows with no significant differences in parity, body weight, and milk yield were selected and randomly divided into four groups of 20 replicates each, with each head as a replicate. The control group was fed a basal diet, and unflower straw in the experimental groups was replaced with 20% (Group I), 50% (Group II), and 100% (Group III) corn stover in the basal diet, respectively. The experiment lasted for 100 days, including 10 days of pre-test and 90 days of formal experiment. The results showed that compared with the control group, the dry matter intake of the three experimental groups was significantly increased (P<0.05), the apparent digestibility of dry matter was significantly increased (P<0.05), the apparent digestibility of crude protein in all experimental groups was extremely increased (P<0.01). The somatic cell count in the milk of Group II was significantly reduced (P<0.05), the microbial protein content in Group III was significantly decreased (P<0.05). GroupsII and III showed a significant increase in the levels of total protein and albumin in serum at 60 and 90 days (P<0.05). The production efficiency of Group I increased by 4.51 yuan/head per day. The study shows that replacing corn stover with 20% sunflower stalks can increase dairy cows' feed intake, improve digestion and absorption of nutrients, and improve milk production and quality, with no adverse effects on the rumen environment and liver and kidney function, and with better economic benefits. [ABSTRACT FROM AUTHOR]

The experiment aimed to investigate the effects of different levels of Chinese herbal additives on the growth performance, serum biochemical indicators, and diarrhea condition of lactating lambs, in order to screen for the appropriate addition level. A total of 48 healthy male lactating lambs with an aged 23 days and a body weight of (6.59±0.03) kg were selected and divided into four groups using a single-factor randomized block design, with three replicates per group and four lambs per replicate. The control group was fed with a basic concentrate, while the experimental groups were fed with concentrate feed containing 0.1% (group 1), 0.3% (group 2), and 0.5% (group 3) Chinese herbal additives, respectively. The trial period was 37 days, with a preliminary trial period of 7 days and a formal trial period of 30 days. The results indicated that compared to the control group, group 1, and group 2, the weight of lambs in the group 3 was extremely increased at 45 and 60 days of age (P<0.01), and the average daily weight gain was extremely increased from 30 to 60 days of age (P<0.01). Compared to the control group, the weight of lambs in the group 2 was extremely increased at 60 days of age (P<0.01), and the feed-to-gain ratio was extremely decreased for the groups 2 and 3 from 30 to 60 days of age (P<0.01). Compared to the control group, the levels of serum glucose (GLU), insulin (INS), total cholesterol (TC), triglycerides (TG), and total protein (TP) in lambs from the group 3 were extremely increased (P<0.01), the albumin (ALB) content was significantly increased (P<0.05), glucagon (PG) content was extremely decreased (P<0.01), and non-esterified fatty acids (NEFA) content was significantly decreased (P<0.05). The TP content in lambs from the group 2 was significantly increased (P<0.05). The levels of β-hydroxybutyrate (β-HB) and blood urea nitrogen (BUN) in lambs from the groups 2 and 3 were significantly decreased (P<0.05), and uric acid (UA) content was extremely decreased (P<0.01). Compared to the control group, the diarrhea rate was extremely decreased (P<0.01), and the recovery rate was extremely increased (P<0.01), with a significant decrease in recovery time (P<0.01) for lambs in the groups 2 and 3. Studies show that the addition of Chinese herbal additives to lactating lamb concentrate can improve the growth performance of lambs, enhance the metabolism synthesis of nutrients, prevent and control the occurrence of diarrhea and accelerate the recovery of diarrhea in lambs, and the addition amount of 0.5% is the best effect. [ABSTRACT FROM AUTHOR]

The experiment was conducted to study the effects of yeast hydrolysate on the mental status, serum biochemical indexes, and intestinal flora of calves. A total of 30 one-day-old Holstein female calves with body weight (39±2) kg were selected and randomly divided into a control group and experimental group (supplemented with 5 g/(head⋅d) yeast hydrolysate), with 15 replicates in each group and one calf in each replicate. Pre-trial period is seven days, and the formal trial period is 56 days. The results showed that the supplementation of 5 g/(head⋅d) yeast hydrolysate could improve the mental status, fur state and fecal scores of calves. On the 63 days, compared with the control group, the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the concentrations of total protein (TP), albumin (ALB), globulin (GLB), blood glucose (GLU), urea nitrogen (BUN) and cholesterol (TC) in serum of calves in experimental group were significantly increased (P<0.05). On the 35 days, the Chao1 and Observed-species indices of fecal microbiota in the experimental group were significantly reduced (P<0.05). Compared with the microbial genus level, the abundance of Faecalibacterium in fecal flora increased on the 14th day. The richness of Faecalibacterium in the fecal flora decreased on the 35th day. The results show that supplementation of 5 g/(head ⋅d) yeast hydrolysate can improve the mental state, fur state and feces of calves, improve the serum biochemical indexes, increase the abundance of intestinal beneficial flora, and promote the healthy growth of calves. [ABSTRACT FROM AUTHOR]

The use of health-food additives has gained significant attention within the dairy sector, with a focus on enhancing the nutritional intake of dairy cows to improve their productivity and reproductive performance. This study aims at examining the impact of rumen-protected methionine (Met) and lysine (Lys) supplementation on production and reproductive parameters in a sample of 100 dairy cows, comprising 32 primiparous and 68 multiparous cows with an average age of 5.24 ± 2.31 years. The cows' average milk production was determined to be 24.9 ± 7.40 kg/day. The cows were divided into two groups, one receiving Met/Lys supplementation and the other serving as a control group. The supplemented group demonstrated superior performance in various metrics: milk yield (25.61 kg/day vs. 24.16 kg/day, p < 0.0001), fat (979.02 g/day vs. 874.27 g/day, p = 0.08), protein (843.98 g/day vs. 761.50 g/day, p = 0.10), and lactose content (4.36% vs. 4.21%, p = 0.003). Supplementation also led to elevated levels of butyrate and protein. Notably, the supplemented cows exhibited higher body condition scores (BCS) at different stages of lactation, with BCS values of 3.01 at 35 days and 2.80 at 65 days, compared to 2.83 and 2.61 in the control group. Additionally, Met/Lys supplementation resulted in higher levels of albumin (33.22 g/L) and urea (0.20 g/L) in serum samples, with a tendency towards increased levels of aspartate aminotransferase (51.20 U/L). Reproductive performance showed improvements in the supplemented group with a lower number of services per conception (1.88 vs. 2.05), a higher conception rate (44.83% vs. 22.22%), and a higher total pregnancy rate (55% vs. 48%), although these differences were not statistically significant. Thus, the addition of rumen-protected Met and Lys to dairy cow rations shows potential for enhancing milk production and composition, as well as improving specific metabolic and reproductive characteristics. [ABSTRACT FROM AUTHOR]

The widespread adoption of automatic milking systems (AMS) in the United States has afforded dairy cows the flexibility to establish personalized milking, feeding, and resting schedules. Our study focused on investigating the short-term effects of transitioning milking permissions from every 4 (MP4) to 6 (MP6) hours on the 100th day of lactation on milking frequency, milk yields, and cow behavior. Twenty-four Holstein dairy cows were divided into control (maintaining a 4 h milking interval) and test groups (transitioning to a 6 h milking interval) and observed for 6 days. The analysis revealed that parity and treatment had no significant impact on milking frequency, milk/visit, or daily milk yield. However, multiparous cows spent more time inside the commitment pen, while test group cows exhibited more tail-swishing and displacement behavior, approached the AMS more frequently, and spent longer idle times. The interaction between parity and treatment influenced heart rate variability parameters, indicating increased stress in the test group cows. Additionally, the test group cows had greater total and daytime lying frequencies, suggesting short-term behavioral modifications. Despite no immediate impact on milk production, further research is recommended to assess the potential long-term effects on milk yield in AMS farms, considering the identified stress indicators short-term. [ABSTRACT FROM AUTHOR]

Simple Summary: This study indicates that a high grain diet (HG) significantly reduces the milk fat content of lactating cows. In addition, the HG group promoted rumen fermentation by altering the microbial composition of lactating cows. The concentration of short-chain fatty acids (SCFAs) in the HG group was increased by increasing the abundance of Prevotella and Xanthomonas, providing more energy to the body, while increasing the abundance of Stenotrophomonas, which increased the probability of mastitis. However, 16S sequencing still cannot reflect the true physiological changes in the host. Therefore, future research should investigate the effects between diet, microorganisms, and hosts to facilitate managers to use high-grain diets rationally to achieve high yields. The objectives of the current study were to evaluate the fluctuations in production performance, rumen fermentation, and microbial community in lactating dairy cows fed a high-grain diet (HG). In this study, 16 healthy Holstein lactating dairy cattle with similar milk yields of 16.80 ± 4.30 kg/d, days in milk 171.44 ± 23.25 days, and parity 2.2 ± 1.5 times were selected and randomly allocated into two groups. One group was fed a low-grain diet (LG; 40% concentrate, DM basis; n = 8), and the other group was fed a high-grain diet (HG; 60% concentrate, DM basis; n = 8). The experiment lasted 6 weeks, including 1 week for adaptation. The experimental results showed that the milk fat content in the milk of lactating cows in the HG group was significantly reduced (p < 0.05), and the milk urea nitrogen (MUN) content showed an increasing trend (0.05 < p < 0.10) compared with the LG group. Compared with the LG group, rumen fluid pH was significantly decreased after feeding a high-grain diet, and contents of total volatile fatty acids (TVFA), acetate, propionate, and butyrate were significantly increased (p < 0.05). The acetate/propionate significantly decreased (p < 0.05). HG group significantly increased the abundance of Prevotella and Bacteroides in rumen fluid while significantly reducing the abundance of Methanobrevibacter and Lachnospiraceae ND3007_group (p < 0.05). Microorganisms with LDA scores > 2 were defined as unique, with the bacterial genus Anaerorhabdus_furcosa_group identified as a biomarker for the LG group, and the unique bacterial genus in the HG group were Prevotella, Stenotrophomonas, and Xanthomonadaceae. The prediction results of microbial function showed that a total of 18 KEGG differential pathways were generated between the two treatment groups, mainly manifested in metabolic pathways, signal transduction, and the immune system. In conclusion, the HG group promoted rumen fermentation by altering the microbial composition of lactating cows. Our findings provide a theoretical basis for the rational use of high-grain diets to achieve high yields in intensive dairy farming. [ABSTRACT FROM AUTHOR]

Simple Summary: Adding the phytoactive mixture to the dairy cows' diet positively affected animal nutrition and health, improving Jersey production efficiency. The intake of phytogenics improved milk quality, reduced somatic cell counts, and increased unsaturated fatty acids. The intake of phytogenics per cow protected the mammary gland from bacteria Streptococcus spp. The phytoactive mixture directly affected the digestibility and modulation of the volatile fatty acid profile. The phytoactive mixture positively affected immune and antioxidant responses and anti-inflammatory action. This study's objective was to evaluate whether adding a combination of phytoactive (microencapsulated essential oils, minerals, turmeric extract, tannin, prebiotic, and probiotic) to the feed of lactating Jersey cows positively affects the production, composition, and quality of milk, rumen environment, and animal health. Fourteen Jersey cows were divided into two groups (control and phytogenic) for an experiment with two lactation phases of 45 days each (early lactation and mid-lactation). During the experiment, milk production was higher at various times in cows that consumed phytoactive, and these animals had the best feed efficiency. In mid-lactation, phytoactive intake increased nutrient digestibility. The number of lymphocytes in the blood is reduced when cows consume phytoactive substances. Globulin levels increased in these cows fed with the additive, which may be related to a higher concentration of immunoglobulins, especially IgA. Cows fed phytoactives had lower ceruloplasmin and haptoglobin concentrations. Lower serum lipid peroxidation, associated with greater glutathione S-transferase activity, is a good health indicator in cows that consume phytoactive substances. The higher concentration of volatile fatty acids was due to the higher proportion of acetic acid in the ruminal fluid combined with lower butyric acid. Somatic cell counts in milk were lower in cows that consumed phytoactives during mid-lactation, as well as the effect of the treatment on Streptococcus spp. (lower in cows that consumed the additive). We conclude that consuming the additive benefits cows' health modulates rumen fermentation and nutrient digestibility, and positively affects milk production and quality. [ABSTRACT FROM AUTHOR]

Extending lactation length reduces the frequency of critical calving events for the cow and herewith reduces the frequency of periods with increased risk for health problems. Moreover, breeding is postponed until a moment later in lactation, which is associated with better conception rates and less days open after start of the breeding period in most studies. Potential risks of an extended lactation are that milk yield of cows at the end of the lactation may be too low which may lead to cows being overconditioned at the end of the extended lactation. Therefore, extending lactation length might not fit every cow. Individual cow characteristics like parity, milk yield level, or body condition determine the response of the cow to an extended lactation. These individual cow characteristics can be used in customized management strategies to optimize lactation length for individual cows. Customized lactation length for individual cows could limit the impact at herd level of disadvantages concerning milk losses and overconditioning and maintain benefits for improved cow health and fertility, reduced number of surplus calves and increased work satisfaction for the farmer. In conclusion, extending lactation length has interesting perspectives for health and fertility of high‐producing dairy cows, although questions remain concerning management approaches to support lactation persistency of cows with an extended lactation, and consequences for calf health and development. Moreover, ongoing studies aim to develop decision support tools to select individual cows for a specific lactation length. [ABSTRACT FROM AUTHOR]