Search

The present study investigates the susceptibility of two imported dairy cattle breeds to Algerian local climatic conditions, with a primary focus on heat stress (HS) and its repercussions on fertility traits. The dataset comprises 20,926 artificial insemination records involving 6,191 Prim'Holstein and 5,279 Montbéliarde cows. The animals originated from three distinct agro-ecological regions: littoral (L), semi-arid (SA), and arid (Ar), characterized by average annual Temperature-Humidity Index (THI) values of 75.2, 69.53, and 74.75, respectively. Logistic and linear regression models were performed to analyze the relationship between the THI on the AI day, season, and agro-ecological origin of the animals with the Conception Rate at 1st Artificial Insemination (CR 1stAI), Conception Risk (CR), Services per Conception (SPC), and reproductive period (RP). The results demonstrated a significant negative impact (P < 0.001) of THI > 72 compared to THI ≤ 72 on CR1st AI and CR for both cattle breeds (Prim'Holstein: -49.7% and − 17%, respectively; Montbéliarde: -20.7% and − 15%, respectively). Seasonal effects revealed a notably higher CR1stAI in winter and spring (≈ 25%) for Prim'Holstein and Montbéliarde cows compared to summer (19.41%) and autumn (19.12%), respectively. Furthermore, a reduced likelihood of conception at 1stAI and subsequent AI was observed during summer (0.839) and autumn (0.818) compared to winter for the Montbéliarde cows. Taking into account the littoral region as a reference, the likelihood of 1stAI success increased for both breeds in the SA region and decreased for the Ar region (P < 0.001). SPC increased for both breeds in THI > 72 categories (Prim'Holstein: 6.3%, Montbéliarde: 7.1%, P < 0.01), in the Ar region (Prim'Holstein: 30.9%, Montbéliarde: 26%, P < 0.001), and in the SA region (4%, P < 0.05) compared to the L region No significant seasonal effect on SPC was observed for either breed (P > 0.05). The RP increased in the THI > 72 category (Prim'Holstein: 4.1%, Montbéliarde: 7.4%, P < 0.001) and in the Ar region (Prim'Holstein: 122%, Montbéliarde: 73.4%) for both breeds. RP decreased in autumn compared to winter (Prim'Holstein: 15.3%, Montbéliarde: 8.4%). This study underscores the adverse impact of mild to severe heat stress (HS) and related factors (season, region) on fertility of Prim'Holstein and Montbéliarde cows under Algerian conditions, emphasizing the necessity for heat stress mitigation strategies, especially in adverse littoral humid and Saharan-arid environmental conditions. [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 performance of an adult dairy cow may be influenced by heat stress that occurs during her gestation. The present study investigated potential effects of temperature-humidity index (THI) experienced by a cow during pregnancy on the gestated daughter's performance on her first lactation, for the French Holstein and Montbéliarde dairy cattle populations. We analyzed 14 traits, all measured on genotyped cows: 305-d milk, fat, and protein yields; 305-d SCS; clinical mastitis (both occurrence and number of events); body conformation traits; and heifer and cow conception rate. To study the effect of heat stress, we considered the THI experienced by the gestating cow, averaged for each month of her pregnancy and then categorized in 7 classes (≤40, [40,45], [45,50], [50,55], [55,60], [60,65], and >65). These average THI classes were then fitted as categorical covariates in the regression models used for this study, which included other fixed effects, and the GEBV as a covariate, both specific to each trait, the latter being previously obtained from the official French evaluations. The THI effect was therefore estimated as the deviation between the observed and predicted performances. In general, the estimated heat stress effects were small, presenting limited practical impact on the studied traits, and particularly for fertility and udder health, the estimated heat stress effects were not statistically significant. For the production traits (i.e., milk, fat, and protein yields), the estimated effect associated with high THI experienced at the beginning of the gestation was negative, and slightly positive when associated with high THI experienced by the dam at the end of her pregnancy. Finally, our results suggest that under the current French climate conditions, heat stress experienced by cows during any stage of their pregnancy has limited impact on the future performance of their gestated daughters; however, we cannot exclude that a significant in utero heat stress effect may be present in climate conditions warmer than the French. [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. Third-generation cephalosporins such as ceftiofur are critically important antibiotics because human pathogens with resistance to these drugs contribute to high mortality rates. These antibiotics are also frequently given to dairy cattle for treating infections, emphasizing the critical role they play in both human and veterinary medicine. To investigate the effect of intramuscular ceftiofur treatment on the concentration of resistant bacteria in the gut, we focused on cows with metritis, a common bacterial infection that frequently requires antibiotic intervention. Twelve cows with metritis (cases) were enrolled and treated with intramuscular ceftiofur for 5 d along with 12 matched healthy cows that were not given ceftiofur (controls). Fecal samples were collected weekly from cows in both the case and control groups for 4 wk, starting before the treatment of the case group. Five fecal samples per cow were used for analysis (n = 120 samples). The abundance of gram-negative bacteria was quantified per sample after plating on MacConkey agar, which was also used to quantify the abundance of gram-negative bacteria with resistance to ceftiofur, ampicillin, and tetracycline. Interestingly, the case cows with metritis had a greater abundance of gram-negative bacteria than the control cows just before treatment, but no difference in abundance was observed between groups at wk 1–4. The abundance of ceftiofur-resistant gram-negative bacteria was also similar between the case and control cows immediately before treatment of the cases. However, a significant increase in abundance of ceftiofur-resistant gram-negative bacteria was observed in the case cows 1-wk after treatment that persisted through wk 3. Although the recovery of ampicillin- and tetracycline-resistant bacteria was similar between the 2 groups post-treatment, cases had significantly higher levels of ampicillin-resistant bacteria before treatment. Collectively, these findings demonstrate that metritis and intramuscular ceftiofur treatment can affect the abundance of cultivable gram-negative bacteria and ceftiofur-resistant populations that can persist for up to 3 wk. Judicious use practices are needed to ensure that ceftiofur and other critically important antibiotics are administered only when necessary to minimize the spread of resistance and safeguard public and animal health. [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. Traits related to calving have a significant impact on animal welfare and farm profitability in dairy production systems. Identifying genomic regions associated with calving traits could contribute to refining dairy cattle breeding programs and management practices in the dairy industry. Therefore, the primary objectives of this study were to estimate genetic parameters and perform GWAS and functional enrichment analyses for stillbirth, gestation length, calf size, and calving ease traits in North American Jersey cattle. A total of 40,503 animals with phenotypic records and 5,398 animals genotyped for 45,101 SNPs were included in the analyses. Genetic parameters were estimated based on animal models and Bayesian methods. The effects of SNPs were estimated using the single-step GBLUP method. The heritability (SE) estimates ranged from 0.01 (0.01) for stillbirths in heifers to 0.11 (0.01) for gestation length in cows. The genetic correlations ranged from −0.58 (0.11) between calving ease and stillbirths in heifers to 0.44 (0.14) between calving ease and calf size in cows. Calving ease showed the highest genetic correlation between heifers and cows, 0.8 (0.22) respectively. The candidate genes identified, including MTHFR , SERPINA5 , IGFBP3 , and ZRANB1 , are involved in key biological processes and metabolic pathways related to the studied traits. Reducing environmental variation and identifying novel indicators of reproduction traits in the Jersey breed are needed given the low heritability estimates for most traits evaluated in this study. In conclusion, this study provides a characterization of the genetic background of calving-related traits in Jersey cattle. The estimates obtained can be used to improve or build selection indexes in Jersey cattle breeding programs in North America. [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. One suggested approach to improve the reproductive performance of dairy herds is through the targeted management of subgroups of biologically similar animals, such as those with similar probabilities of becoming pregnant, termed pregnancy risk. We aimed to use readily available farm data to develop predictive models of pregnancy risk in dairy cows. Data from a convenience sample of 108 dairy herds in the UK were collated, and each herd was randomly allocated, at a ratio of 80:20, to either training or testing datasets. Following data cleaning, there were a total of 78 herds in the training dataset and 20 herds in the testing dataset. Data were further split by parity into nulliparous, primiparous, and multiparous subsets. An XGBoost model was trained to predict the insemination outcome in each parity subset, with predictors from farm records of breeding, calving, and milk recording. Training data comprised 74,511 inseminations in 45,909 nulliparous animals, 86,420 inseminations in 39,439 primiparous animals, and 158,294 inseminations in 32,520 multiparous animals. The final models were evaluated by predicting with the testing data, comprising 31,740 inseminations in 19,647 nulliparous animals, 38,588 inseminations in 16,215 primiparous animals, and 65,049 inseminations in 12,439 multiparous animals. Model discrimination was assessed by calculating the area under receiver operating characteristic curves (AUC); model calibration was assessed by plotting calibration curves and compared across test herds by calculating the expected calibration error (ECE) in each test herd. The models were unable to discriminate between insemination outcomes with high accuracy, with an AUC of 0.63, 0.59, and 0.62 in the nulliparous, primiparous, and multiparous subsets, respectively. The models were generally well calibrated, meaning the model-predicted pregnancy risks were similar to the observed pregnancy risks. The mean (SD) ECE in the test herds was 0.038 (0.023), 0.028 (0.012), and 0.020 (0.008) in the nulliparous, primiparous, and multiparous subsets respectively. The predictive models reported here could theoretically be used to identify subgroups of animals with similar pregnancy risk to facilitate targeted reproductive management; or provide information about cows' relative pregnancy risk compared with the herd average, which may support on-farm decision making. Further research is needed to evaluate the generalizability of these predictive models and understand the source of variation in ECE between herds; however, this study demonstrates that it is possible to accurately predict pregnancy risk in dairy cows using readily available farm data. [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. Antimicrobial resistance (AMR) is one of the greatest threats to global health worldwide and is threatening not only humans, but also animal production systems, including dairy farms. The objective of this paper was to describe risks factors associated with AMR on dairy farms in Québec, Canada. This observational cross-sectional study included 101 commercial dairy farms and took place over a one-year period between the spring of 2017 and the spring of 2018. We explored risk factors such as farm practices and producer knowledge (measured using a questionnaire), antimicrobial use (quantified using veterinary invoices), and the presence of Salmonella Dublin (tested by serology). We evaluated AMR with fecal Escherichia coli retrieved from preweaning calves and lactating cows using the following outcomes: the presence of extended-spectrum β-lactamase/AmpC resistance and the number of resistances to antimicrobial classes. We used logistic regression models to evaluate the association between each risk factor and the 2 outcomes for the 2 types of samples (preweaning calves and lactating cows). Furthermore, we explored the relationships between these risk factors utilizing data dimensionality reduction and hierarchical clustering. Outputs of these analyses were used as regressors for AMR in regression models. Although the results for univariate analyses were ambiguous, the unsupervised analysis naturally categorized the sample of farms according to their health and treatment status (dimension 1, explaining 12.9% of the variance) and herd size (dimension 2, explaining 7.8%). Three clusters of farms were identified (cluster 1: mainly healthy herds and low ceftiofur users, cluster 2: relatively high ceftiofur users, cluster 3: farms with a higher incidence of diseases and higher antimicrobial treatment rates). Dimension 1 and cluster membership were statistically associated with the presence of extended-spectrum β-lactamase/AmpC resistance in lactating cows and in preweaning calves. Dimension 1 was also statistically associated with the number of resistances in lactating cows and in preweaning calves. This study highlights the complexity of analyzing risk factors associated with AMR. Our results suggest that the herd health status and the antimicrobial use-related practices used are associated with AMR in dairy farms. However, prospective studies are needed to confirm a causal relation. [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. Genome-wide association studies are employed to identify genomic regions and candidate genes associated with several traits. The aim of this study was to perform a GWAS to identify causative variants and genes associated with milk yield, frame, and udder-conformation traits in Gir dairy cattle. Body conformation traits were classified as "frame," and "udder" traits for this study. After genotyping imputation and quality control 42,105 polymorphisms were available for analyses and 24,489 cows with pedigree information had phenotypes. First, P -value was calculated based on the variance of the prediction error of the SNP effects on the first iteration. After that, 2 more iterations were performed to carry out the weighted single-step genome-wide association methodology, performed using genomic moving windows defined based on linkage disequilibrium. The significant SNPs and top 10 windows explaining the highest percentage of additive genetic variance were selected and used for QTL and gene annotation. The variants identified in our work overlapped with QTL from the animal QTL database on chromosomes 1 to 23, except for chromosome 4. The Gir breed is less studied than the Holstein breed and as such the animal QTL database is biased to Holstein results. Hence it is noteworthy that our GWAS had similarities with previously described QTL. These previously known QTL were related to milk yield, body height, rump angle, udder width, and udder depth. In total, 5 genes were annotated. Of these genes, FAM13A and CMSS1 had been previously related to bone and carcass weight in cattle. [ABSTRACT FROM AUTHOR]

Modern livestock production systems are characterized by a greater focus on intensification, involving managing larger numbers of animals to achieve higher productive efficiency and animal health and welfare within herds. Therefore, animal breeding programs need to be strategically designed to select animals that can effectively enhance production performance and animal welfare across a range of environmental conditions. Thus, this review summarizes the main methodologies used for assessing the levels of genotype‐by‐environment interaction (G × E) in cattle populations. In addition, we explored the importance of integrating genomic and phenotypic information to quantify and account for G × E in breeding programs. An overview of the structure of cattle breeding programs is provided to give insights into the potential outcomes and challenges faced when considering G × E to optimize genetic gains in breeding programs. The role of nutrigenomics and its impact on gene expression related to metabolism in cattle are also discussed, along with an examination of current research findings and their potential implications for future research and practical applications. Out of the 116 studies examined, 60 and 56 focused on beef and dairy cattle, respectively. A total of 83.62% of these studies reported genetic correlations across environmental gradients below 0.80, indicating the presence of G × E. For beef cattle, 69.33%, 24%, 2.67%, 2.67%, and 1.33% of the studies evaluated growth, reproduction, carcass and meat quality, survival, and feed efficiency traits, respectively. By contrast, G × E research in dairy cattle populations predominantly focused on milk yield and milk composition (79.36% of the studies), followed by reproduction and fertility (19.05%), and survival (1.59%) traits. The importance of G × E becomes particularly evident when considering complex traits such as heat tolerance, disease resistance, reproductive performance, and feed efficiency, as highlighted in this review. Genomic models provide a valuable avenue for studying these traits in greater depth, allowing for the identification of candidate genes and metabolic pathways associated with animal fitness, adaptation, and environmental efficiency. Nutrigenetics and nutrigenomics are emerging fields that require extensive investigation to maximize our understanding of gene–nutrient interactions. By studying various transcription factors, we can potentially improve animal metabolism, improving performance, health, and quality of products such as meat and milk. [ABSTRACT FROM AUTHOR]

The study objective was to evaluate the effect of replacing the second gonadotropin releasing hormone (GnRH2) of the Ovsynch and Co-Synch protocols with human chorionic gonadotropin (hCG) on ovulation, conception, pregnancy, and embryo loss rates in primiparous lactating dairy cows. Forty- nine primiparous Holstein cows 53 to 65 days in milk were allocated to the following groups: (1) OVS (Ovsynch; n=12): GnRH, 7 days, PGF2α, 56 hours, GnRH, 16-18 hours, timed artificial insemination (TAI); (2) COS (Co-Synch; n = 12): GnRH, 7 days, PGF2α, 72 hours, GnRH + TAI; (3) OVS-hCG (Ovsynch + hCG; n = 12): as OVS except that GnRH2 was replaced with 1500 IU hCG; (4) COS-hCG (Co-Synch + hCG; n = 13): as COS except that GnRH2 was replaced with 1500 IU hCG. Ovaries of all animals were scanned by transrectal ultrasonography to determine the incidence of ovulation on days 9, 10 and 11 at 24-hour intervals after the initiation of the treatments (day 0). Ovulation was defined as the disappearance from one scanning session to the next of a previously identified follicle ≥ 8 mm in diameter. Pregnancy diagnosis was performed by transrectal ultrasonography on days 30 ± 1 and 42 ± 1 post TAI to determine conception and pregnancy status, respectively. The results showed that the animals in OVS tended to have higher ovulation and conception rates (P=0.08). In addition, pregnancy rate was higher and embryo loss rate was lower for OVS than the other groups, but the differences were not significant (P>0.05). It was concluded that replacing GnRH2 with hCG in the Ovsynch and Co-Synch programmes has no beneficial effect on the reproductive performance of primiparous Holstein cows. However, conducting the experiment at a larger scale may provide more precise results. [ABSTRACT FROM AUTHOR]

We offer a perspective on the major challenges that are confronting the management of reproduction in sheep and cattle in Australia and New Zealand, over the next two decades. An important context is the dominance of grazing systems in which large flocks or herds are managed over large areas where it is challenging to manage reproduction with precision. Consequently, the variable forage supply usually dominates reproductive outcomes, a problem that will be exacerbated by global heating. Thus, in extensive grazing systems, there is a great need for technological solutions to improve the management of nutrition. Global heating will also exert direct effects on reproductive function. Therefore, for the foreseeable future, reproduction will remain a focus for industry. In addition, as the industries develop, we foresee continued societal pressure to reduce medication, mitigate environmental damage, and improve animal well-being. Management solutions for extensive grazing systems must involve minimal interventions with the animals and be applicable to diverse genotypes and environments. Clearly, genetics and breeding will be at the heart of solutions and elegant strategies will be needed that focus on developing animals that are robust, if perhaps a little less productive. A high rate of genetic gain is the main reason for pursuing reproductive technologies, but highly advanced reproductive technology is not likely to be the best fit in extensive management systems. Even for AI, the simplest technology, uptake is limited and lateral thinking is needed to find ways to improve the rates of genetic gain. We conclude that there are many opportunities for improving reproductive performance in sheep and cattle in Australia and New Zealand. As we gain deeper understanding of the processes involved, we should be able to make progress in fertility and fecundity, embryo survival, and postnatal survival. Improvements in reproductive performance will increase productivity, and should also be associated with significantly improved animal well-being and a reduction in methane emissions intensity. To capture these benefits, the development of new management options will require lateral thinking about reproductive technology for extensive grazing systems, and a transdisciplinary approach that brings together the systems biology of grazing animals with an understanding of the barriers to adoption by farmers. • The context for management of reproduction is large flocks or herds grazing over large areas. • Nutrition-reproduction is key – feed supply is variable, becoming more so with climate change. • Extreme weather events caused by climate change might directly affect reproduction. • Reproduction is an industry focus, but transdisciplinary problem-solving will be needed. • Intensive ART not likely for genetic strategies so lateral thinking is needed. [ABSTRACT FROM AUTHOR]

In the present study, a comparative global high-throughput proteomic analysis strategy was used to identify proteomic differences between estrus and diestrus stage of estrous cycle in dairy cows. Saliva was collected from cows during estrus and diestrus, and subjected to LC-MS/MS-based proteomic analysis. A total of 2842 proteins were detected in the saliva of cows, out of which, 2437 and 1428 non-redundant proteins were identified in estrous and diestrous saliva, respectively. Further, it was found that 1414 and 405 salivary proteins were specific to estrus and diestrus, respectively while 1023 proteins were common to both groups. Among the significantly dysregulated proteins, the expression of 56 proteins was down-regulated (abundance ratio <0.5) while 40 proteins were up-regulated (abundance ratio > 2) in estrous compared to diestrous saliva. The proteins, such as HSD17B12, INHBA, HSP70, ENO1, SRD5A1, MOS, AMH, ECE2, PDGFA, OPRK1, SYN1, CCNC, PLIN5, CETN1, AKR1C4, NMNAT1, CYP2E1, and CYP19A1 were detected only in the saliva samples derived from estrous cows. Considerable number of proteins detected in the saliva of estrous cows were found to be involved in metabolic pathway, PI3K-Akt signaling pathway, toll-like receptor signaling pathway, steroid biosynthesis pathway, insulin signaling pathway, calcium signaling pathway, estrogen signaling pathway, oxytocin signaling pathway, TGF-β signaling pathway and oocyte meiosis. On the other hand, proteins detected in saliva of diestrous cows were involved mainly in metabolic pathway. Collectively, these data provide preliminary evidence of a potential difference in salivary proteins at different stages of estrous cycle in dairy cows. [ABSTRACT FROM AUTHOR]

Background: Crossbreeding beef bulls with dairy cows can improve the economic value and fitness of calves not entering dairy production owing to increased meat yield and heterosis. However, outcrossing might reduce the dosage of alleles that confer local adaptation or result in a higher risk of dystocia due to increased calf size. Given the clear phenotypic differences between beef breeds, the varying phylogenetic distances between beef and dairy breeds, and the genomic variations within breeds, the attainable economic and fitness gains of calves will strongly depend on the selection of sires for crossing. Thus, the aim of this study was to assess genome complementarity between Angus (AAN), Limousin (LIM), or Simmental (SIM) beef bulls and Brown Swiss (BSW) dairy cows by quantifying genomic inbreeding reduction in F1 crosses and identifying genes potentially under BSW-specific selection that might be affected by outcrossing. Results: Low-pass sequencing data from 181 cows, 34 bulls, and 301 of their F1 progeny, and body weight and carcass composition measurements of 248 F1s were obtained. The high genomic inbreeding levels detected in the BSW cows were substantially reduced in the crossbreds, with only minor differences between the sire breeds. In the BSW cows, 585 candidate genes under selection were identified, overrepresenting genes associated with milk, meat and carcass, and production traits. Only a few genes were strongly differentiated at nonsynonymous variants between the BSW and beef breeds, including four tightly clustered genes (FAM184B, NCAPG, DCAF16, and LCORL) nearly fixed for alternate alleles in the BSW cows but mostly heterozygous or homozygous for the reference alleles in the AAN and LIM bulls. The alternate allele dosage at these genes significantly correlated with reduced carcass weight and protein mass in F1s. Conclusion: Some of the few genes that were highly divergent between the BSW and beef breeds at nonsynonymous variants were likely under strong selection for reduced carcass weight in the BSW breed, potentially due to trade-offs between beef and dairy productions. As alleles with opposing effects still segregate in beef cattle, marker-assisted selection of mating pairs may be used to modulate the desired phenotypes and simultaneously decrease genomic inbreeding. [ABSTRACT FROM AUTHOR]

Simple Summary: Agricultural greenhouse gas emissions account for 14.5% of global anthropogenic emissions, with beef and dairy cattle contributing 35% and 30% of global livestock emissions, respectively. This study focuses on dairy cattle, exploring the relationships between rumen microbiota and methane emission. Using a laser methane detector (LMD), methane emissions from 968 lactating cows were measured, and 107 cows were selected for high and low emission groups. The results showed that the abundance of Bacteroidales and Prevotellaceae in the rumen of high methane-emitting cows was significantly higher than that in the low methane-emitting cows. Additionally, it was found that bacterial functions related to biosynthesis and carbohydrate metabolism were more active in the high methane-emitting cows. These findings provide new insights for developing strategies to reduce methane emissions, supporting the sustainable development of the dairy industry. Agricultural activities are a significant contributor to global greenhouse gas emissions, accounting for 14.5% of total anthropogenic emissions. Specifically, greenhouse gas emissions from beef cattle and dairy cattle constitute 35% and 30% of total global livestock emissions, respectively. This study focuses on dairy cattle, exploring the complex relationships between rumen microbiota and methane emission. The methane emissions of 968 lactating Holstein cows were measured using a laser methane detector (LMD, Shanghai Hesai Technology Co., Ltd., Shanghai, China). Among the measured cows, 107 individuals were further selected into high (HME) and low methane-emitting (LME) groups, including 50 cows in the HME group and 57 in the LME group. This study analyzed differences in rumen microbiota and microbial functions between cows with varying levels of methane emissions. The results showed significant differences in the Simpson and Pielou indices of rumen bacterial communities between the HME and LME groups. Beta diversity analysis revealed significant differences in microbial community structure between the two groups. It was found that the abundance of Bacteroidales and Prevotellaceae in the rumen of cows in the HME group cows was significantly higher than that of cows in the LME group (LDA > 3, p < 0.05). Additionally, bacterial functions related to biosynthesis and carbohydrate metabolism were more active in the HME group. This study revealed distinct differences in the rumen bacterial communities between HME and LME cow in Chinese Holstein cattle, and identified specific bacteria and their functional differences in the HME group. The microbial characteristics and metabolic pathways provide new insights for developing strategies to reduce methane emissions, supporting the sustainable development of the dairy industry. [ABSTRACT FROM AUTHOR]

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]

Over the winter period, the low grass growth and availability in pasture-based dairy systems results in animals being housed and predominantly fed a diet of grass silage. There is limited availability of methane (CH4) data evaluating the impact of forage type on dairy cows over the pre-partum period. The objective of the current experiment was to evaluate the impact of feeding grass clover (GC) silage and grass-only (GO) silage on the dry matter intake (DMI) and enteric CH4 emissions of dairy cows pre-partum. A complete randomised block design was utilised for the 6-week experiment over two winter periods: from December 2020 to January 2021 and from December 2021 to January 2022. In each year, 30 non-lactating pregnant dairy cows were randomly allocated to two treatments (n = 15). In both years, cows in the GC treatment were offered grass clover bale silage, while cows in the GO treatment were offered grass-only pit silage. The DMI and gaseous emissions of individual animals were monitored daily using Hokofarm RIC (roughage intake control) feed stations and the GreenFeed technology. GC silage consistently had greater (p < 0.05) organic matter (OM) digestibility and lower (p < 0.05) neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents when compared with GO silage. Cows in the GC treatment had significantly greater (p < 0.05) total DMI (TDMI) compared with cows in the GO treatment. The daily CH4 emissions (in grams per day) were not affected by treatment; however, cows in the GC treatment had reduced (p < 0.05) CH4 yield (in grams per kilogram TDMI). Offering dairy cows GC silage over the pre-partum period resulted in greater DMI with reduced CH4 yield when compared with cows offered GO silage. [ABSTRACT FROM AUTHOR]

Background: During the transition period, excessive negative energy balance (NEB) lead to metabolic disorders and reduced milk yield. Rumen microbes are responsible for resolving plant material and producing volatile fatty acids (VFA), which are the primary energy source for cows. In this study, we aimed to investigate the effect of citrus peel extract (CPE) supplementation on rumen microbiota composition, energy metabolism and milk performance of peripartum dairy cows. Methods: Dairy cows were fed either a basal diet (CON group) or the same basal diet supplemented with CPE via intragastric administration (4 g/d, CPE group) for 6 weeks (3 weeks before and 3 weeks after calving; n = 15 per group). Samples of serum, milk, rumen fluid, adipose tissue, and liver were collected to assess the effects of CPE on rumen microbiota composition, rumen fermentation parameters, milk performance, and energy metabolic status of dairy cows. Results: CPE supplementation led to an increase in milk yield, milk protein and lactose contents, and serum glucose levels, while reduced serum concentrations of non-esterified fatty acid, β-hydroxybutyric acid, insulin, aspartate aminotransferase, alanine aminotransferase, and haptoglobin during the first month of lactation. CPE supplementation also increased the content of ruminal VFA. Compared to the CON group, the abundance of Prevotellaceae, Methanobacteriaceae, Bacteroidales_RF16_group, and Selenomonadaceae was found increased, while the abundance of Oscillospiraceae, F082, Ruminococcaceae, Christensenellaceae, Muribaculaceae UCG-011, Saccharimonadaceae, Hungateiclostridiaceae, and Spirochaetaceae in the CPE group was found decreased. In adipose tissue, CPE supplementation decreased lipolysis, and inflammatory response, while increased insulin sensitivity. In the liver, CPE supplementation decreased lipid accumulation, increased insulin sensitivity, and upregulated expression of genes involved in gluconeogenesis. Conclusions: Our findings suggest that CPE supplementation during the peripartum period altered rumen microbiota composition and increased ruminal VFA contents, which further improved NEB and lactation performance, alleviated lipolysis and inflammatory response in adipose tissue, reduced lipid accumulation and promoted gluconeogenesis in liver. Thus, CPE might contribute to improve energy metabolism and consequently lactation performance of dairy cows during the transition period. [ABSTRACT FROM AUTHOR]

The risk for transmission of highly pathogenic avian influenza A(H5N1) virus from dairy cows to humans is currently low; however, personal protective equipment (PPE) use during work activities on dairy farms has not been well described. PPE use can protect farmworkers when they are working with highly pathogenic avian influenza A(H5N1)–infected cows. The Colorado Department of Public Health and Environment (CDPHE) and the Colorado Department of Agriculture (CDA) offered PPE to all Colorado farms before or during an A(H5N1) outbreak in cows in 2024. CDPHE surveyed 83 dairy workers from three farms with a confirmed bovine A(H5N1) outbreak. Frequently reported farm worker activities included milking cows or working in the milking parlor (51%), cleaning cow manure (49%), and transporting cows (46%). Frequently reported PPE items available to workers before A(H5N1) outbreaks included gloves (88%), eye protection (e.g., safety glasses or goggles) (76%), rubber boots or boot covers (71%), and head covers (69%). N95 respirator use was low among workers who were exposed to ill cows after detection of A(H5N1) virus (26%). PPE use while working with ill cows increased a mean of 28% after detection of A(H5N1) virus on surveyed farms; use of eye protection while milking cows increased the most (40%). Public health PPE distribution, education, and collaboration with CDA might have increased PPE use on dairy farms with A(H5N1) virus–infected cows and mitigated risk for farmworkers acquiring A(H5N1) virus. [ABSTRACT FROM AUTHOR]

Parenteral antimicrobial treatment results in the excretion of antimicrobial-resistant bacteria. Dairy cows are commonly housed side by side in tie-stalls and often receive antimicrobial treatment. However, studies investigating treated cows as source of colonization of neighboring cows with resistant bacteria are scarce. Antimicrobial resistance (AMR) in cows (treated and untreated) in tie-stalls was investigated to assess their respective risks of carrying resistant bacteria. Furthermore, we analyzed associations of farm management with AMR. Case-control study: For isolation of indicator Escherichia (E.) coli, rectal swab samples were taken. Cows were sampled depending on treatment history and proximity to one another (cow A: recently treated parenterally; cow B: untreated, next to cow A; cow C: untreated, at considerable distance from all treated cows). Antimicrobial susceptibility was tested by microdilution. Associations of AMR with exposure to cow A, treatments, and management were analyzed using generalized mixed-effects logistic models. Susceptibility data on 571 isolates from 131 dairy farms were obtained. Almost no difference in proportions of resistant E. coli was observed between cows B and C (B: 53.4%; C: 57.2%; P = 0.52). Untreated cows had lower odds of carrying resistant E. coli than treated cows (B: OR 0.44, P<0.001; C: OR 0.54, P = 0.007). Non-pansusceptibility of isolates was associated with antimicrobial treatment (1 treatment: OR 2.11, P = 0.001; ≥2: OR 1.76, P = 0.043). Using manure on forage crops was associated with higher odds of pansusceptibility (OR 2.01, P = 0.004). For daily practice, with regard to the risk of AMR transmission, results of this study do not provide evidence for the need to separate treated cows from others during treatment in tie-stalls. [ABSTRACT FROM AUTHOR]

Body conformation traits are directly associated with longevity, fertility, health, and workability in dairy cows and have been under direct genetic selection for many decades in various countries worldwide. The main objectives of this study were to perform genome-wide association studies and functional enrichment analyses for fourteen body conformation traits using imputed high-density single nucleotide polymorphism (SNP) genotypes. The traits analyzed include body condition score (BCS), body depth (BD), bone quality (BQ), chest width (CW), dairy capacity (DC), foot angle (FAN), front legs view (FLV), heel depth (HDe), height at front end (HFE), locomotion (LOC), rear legs rear view (RLRV), rear legs side view (RLSV), stature (ST), and a composite feet and legs score index (FL) of Holstein cows scored in Canada. De-regressed estimated breeding values from a dataset of 39,135 North American Holstein animals were used as pseudo-phenotypes in the genome-wide association analyses. A mixed linear model was used to estimate the SNP effects, which ranged from 239,533 to 242,747 markers depending on the trait analyzed. Genes and quantitative trait loci (QTL) located up to 100 Kb upstream or downstream of the significant SNPs previously cited in the Animal QTLdb were detected, and functional enrichment analyses were performed for the candidate genes identified for each trait. A total of 20, 60, 13, 17, 27, 8, 7, 19, 4, 10, 13, 15, 7, and 13 genome-wide statistically significant SNPs for Bonferroni correction based on independent chromosomal segments were identified for BCS, BD, BQ, CW, DC, FAN, FLV, HDe, HFE, LOC, RLRV, RLSV, ST, and FL, respectively. The significant SNPs were located across the whole genome, except on chromosomes BTA24, BTA27, and BTA29. Four markers (for BCS, BD, HDe, and RLRV) were statistically significant when considering a much stricter threshold for the Bonferroni correction for multiple tests. Moreover, the genomic regions identified overlap with various QTL previously reported for the trait groups of exterior, health, meat and carcass, milk, production, and reproduction. The functional enrichment analyses revealed 27 significant gene ontology terms. These enriched genomic regions harbor various candidate genes previously reported as linked to bone development, metabolism, as well as infectious and immunological diseases. [ABSTRACT FROM AUTHOR]

Increasing global temperatures and the incidence of extreme weather conditions will result in heat stress becoming a greater issue in production animals. Genetic selection and breeding for heat-tolerant animals have been promoted as a possible mitigation strategy in dairy cattle. The objectives of this study were to obtain in-field skin temperature measurements of the eye, muzzle and udder using infra-red thermography to examine the genetic variation in skin temperature within cows of a dairy herd and to estimate the genetic correlations between skin temperature and production traits. Thermal images and herd test records were obtained for the dairy herd at Massey University’s dairy farm 1. Estimates of (co)variances were obtained using the JWAS program with univariate and bivariate animal models. The heritability estimates for the eye, muzzle and udder temperature were low to moderate at 0.20, 0.24 and 0.39, respectively. All genetic correlations between production and temperature traits were positive except for eye temperature with milk yield and protein yield which was negative and weak. These results indicate that it may be possible to select for a greater skin temperature, however, these results need to be validated using a larger sample size. [ABSTRACT FROM AUTHOR]

Alfalfa hay is a commonly used and important feed ingredient in dairy production. To better expand the alfalfa supply market, it is of great significance to explore the impact of alfalfa hay from different sources on dairy cow production performance. This study compared the effects of imported alfalfa hay from America (AAH) and Spain (SAH) on lactation performance and rumen microbiota of cows. Three hundred and sixty healthy mid-lactation Holstein cows with similar body weight, milk yield, and parity were randomly divided into two groups fed diets based on AAH or SAH for a 70-day experimental period. Each group was composed of four pens, with 45 cows in each pen. Daily records were kept for MY per cow and dry matter intake per pen. Twelve randomly selected cows per group were sampled to collect milk, feces, rumen fluid, and blood. The findings revealed no significant differences between the two groups in terms of production performance, nutrient apparent digestibility, serum biochemical indices, or rumen fermentation parameters. However, rumen microbial composition differed significantly between the two groups of cows based on β-diversity. On the genus level, the relative abundance of Prevotella , Succinivibrionaceae_UCG-002 increased while that of NK4A214_group , Ruminococcus , norank_f_F082 and Lachnospiraceae_NK3A20_group decreased in the SAH group compared with AAH group. There was no significant correlation between these core differential bacteria and the molar proportions of acetate and propionate, the concentration of total volatile fatty acids, and milk yield. In conclusion, the feeding effects of SAH were similar to those of AAH. These findings provided a reference for the application of alfalfa hay from different sources and for the improvement of the economic benefit of dairy farms. [ABSTRACT FROM AUTHOR]

Background: Calgranulin B (S100A9) was found to be strongly associated with milk protein percentage in dairy cattle in our previous genome-wide association study. Methods: SNPs in S100A9 were identified via pooled sequencing, and genotyping of 1054 cows was performed individually using MassArray with MALDI-TOFMS technology. Association analyses between the S100A9 SNPs and five milk production traits were conducted using SAS 9.2 software. Functional studies of S100A9 were conducted using quantitative PCR, Western blot, CCK-8, and immunofluorescence assays. Results: In the present study, we further verified that two SNPs in S100A9, g.17115387 C>A and g.17115176 C>A, were significantly associated with milk protein percentage. We found that S100A9 could affect the expressions of caseins CSN1S1, CSN2, and CSN3 in MAC-T cells by regulating the expressions of amino acid transporter genes. We investigated the effects of S100A9 on the PI3K-Akt, WNT, and mTOR pathways, which are well known to play important roles in mammary gland development and milk protein synthesis. Our results suggest that S100A9 regulates the expressions of the relevant genes in these pathways, and thus potentially influences the protein synthesis in the mammary gland. Conclusions: This study demonstrates the important role of the S100A9 gene in the milk protein trait of dairy cattle and provides new insights into the molecular mechanism of milk protein content. [ABSTRACT FROM AUTHOR]

Fasciolosis is a parasitosis of great importance for livestock, as well as for public health, as it is considered by the WHO as a neglected disease. Disease control is complex and reinfections make the use of therapeutic products an unsustainable method from an economic, environmental and health point of view. The aim of this study was to evaluate a new vaccine formulation for dairy cattle, containing soluble Fasciola hepatica antigens associated with Montanide 763 AVG and saponin adjuvants (FhSAMS). The vaccine was tested with two protocols, a single dose and a booster dose 6 months after the first dose. The FhSAMS vaccine proved to be safe, with no side effects. Furthermore, it was able to generate a more robust humoral immune response when a six‐month booster dose was used, in addition to stimulating greater production of IFN‐ʏ, indicating a Th1 profile immune stimulus. [ABSTRACT FROM AUTHOR]

Purpose: The reproductive and production performance of dairy cows determines the profitability of a dairy farm. Method: A questionnaire survey was used to assess reproductive performance and husbandry practices by using 100 randomly selected animal owners. Result: Seventy‐nine percent of animal owners involved were men, ages between 30 and 60. Their education was as follows: 26% were illiterate, 67% in primary school and 7% in secondary school. Ninety‐five percent of them managed their animals extensively and used natural mating and breeding practices (75%). AFS in months were 46.83 ± 0.65 in Ada‐Buke Warego, 46.00 ± 1.36 in Hagalo‐Tulam, 47.08 ± 0.99 in Dicho Aba‐Garmama and 47.29 ± 0.51 in Waligalte. AFC in months were 56.68 ± 0.97 in Ada‐Buke Warego, 58.00 ± 1.36 in Hagalo‐Tulam, 57.23 ± 1.41 in Dicho Aba‐Garmama and 56.24 ± 1.13 in Waligalte. ANSPCs were 1.85 ± 0.08 in Ada‐Buke Warego, 1.67 ± 0.14 in Hagalo‐Tulam, 1.54 ± 0.14 in Dicho Aba‐Garmama and 2.00 ± 0.10 in Waligalte. The mean length of CI in months was 30.88 ± 0.90 in Ada Buke Warego, 29.00 ± 1.68 in Hagalo‐Tulam, 28.62 ± 1.62 in Dicho Aba‐Garmama and 31.06 ± 1.04 in Waligalte. The average year of longevity was 9.22 ± 0.7 in Ada‐Buke Warego, 9.08 ± 0.8 in Hagalo‐Tulam, 9.31 ± 0.13 in Dicho Aba‐Garmama and 9.21 ± 0.8 in Waligalte, but there is no significant association (p ≥ 0.05). AFC in months was 48.00 ± 0.00 in local and 37.20 ± 1.30 in crossbreeds. ANSPC was 1.92 ± 0.06 in locals and 1.10 ± 0.10 in hybrids. AFC for Horro and crossbred dairy cattle were 57.73 ± 0.59 and 48.00 ± 0.00 months, respectively. The mean length of CI was 30.53 ± 0.67 and 29.40 ± 1.99 months in natives and crossbreeds, respectively. The average year of longevity was 9.22 ± 0.05 and 9.10 ± 0.10 years for local and hybrids, respectively. ANSPC for natural mating and AI were 1.92 ± 0.05 and 1.10 ± 0.10, respectively, with significant association (p < 0.05). Conclusion: The reproductive performance of dairy cows in the study area was low, which required the improvement of husbandry practices. [ABSTRACT FROM AUTHOR]

Background: Voluntary waiting period (VWP), housing systems and the presence of a veterinarian are effective factors on reproductive performance of a dairy farm. Objectives: This study aimed to investigate the management practices associated with VWP and its effects on reproductive performance. Methods: A total of 136,943 records of 21,756 cows that calved between 1990 and 2013 were used. A questionnaire was also conducted with the farms involved to determine if they adjust the timing of insemination based on the body condition score (BCS) of the cows, postpartum health situation (PPHS) or environmental factors such as heat stress and season. The impact of changing the VWP selectively, the presence of a veterinarian and the type of barn on reproductive outcomes like days open (DO), number of services per conception (NSPC) and days to first service (DFS) was examined using a linear mixed model. This model considered animals and herds as random factors and management practices as fixed factors in the analysis. Results: Among herds that reported altering the VWP based on heat stress, DFS significantly increased (61.68 ± 0.68 vs. 58.4 ± 0.83) while DO (119.70 ± 1.86 vs. 126.9 ± 2.29) and NSPC (1.98 ± 0.04 vs. 2.48 ± 0.05) reduced compared to herds that did not alter the VWP. Our results showed that farms with a full‐time veterinarian had a better reproductive performance than those with part‐time care (p < 0.05). Housing system was significantly associated with fertility traits, so that cows in free‐stall barns were more fertile than those kept in open‐shed barns. Conclusions: The obtained results from this study indicated that management decisions to selectively altering the VWP led to difference in DFS and improved reproductive performance. [ABSTRACT FROM AUTHOR]

Background: Thiol/disulphide homeostasis (TDH) has a critical role in many cellular activities such as antioxidant protection. Alterations of oxidative stress in the transition period play an important role in development of some diseases and disorders in dairy cows. Objectives: The purpose of this study is to assess the total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), total thiol, native thiol, disulphide and lipid profile in Simmental and Montofon dairy cows (aged 2–3) before and after calving. Methods: Blood samples were collected 233–280 days of pregnancy and the 30 days of post‐partum. Serum total thiol, native thiol and disulphide levels were determined as well as TAS, TOS and paraoxonase‐1 (PON‐1) levels were measured using colorimetric assays. Triglycerides (TG), total cholesterol, HDL cholesterol and LDL cholesterol levels were measured with an automatic analyser. Results: Total thiol (p = 0.038) and disulphide (p = 0.015) levels were higher after calving compare to pregnancy in Montofon. TAS was found lower (p < 0.001), and OSI was higher in both breeds (Montofon p = 0.012, Simmental p = 0.028) after calving than in pregnancy. When compared between pregnancy and after calving levels in the same breed, HDL was found to be higher after calving (p < 0.001) and TG was lower after calving (p = 0.020) in Montofon. PON (p = 0.090), HDL (p < 0.001) and cholesterol levels were found higher (p < 0.001) and TG level was lower (p < 0.001) after calving in Simmental. Conclusions: According to our results, we observed different responses between two breeds before and after calving. There are few studies about TDH in animal research, and this is the first study in the literature that evaluates the TDH along with oxidative stress and lipid profiles in dairy cows in the periparturient and post‐partum period. [ABSTRACT FROM AUTHOR]

Background: Dairy cattle feed supplies in the tropics, and particularly in Ethiopia, are mostly derived from base diets (natural and improved grasslands, agricultural wastes, fodder trees and shrubs), agro‐industrial by‐products and non‐conventional feeds. The availability of major feed resource kinds, sources and dairy cattle feeding practises is primarily influenced by agro‐ecology and season, as well as their interactions. Objectives: The research was carried out in the Chencha District of Gamo Zone, Southern Ethiopia, with the goals of assessing the available, feeding system, opportunity, limits and copying strategy of dairy cattle production, as well as estimating feed balance. Methods: Data were gathered through primary and secondary data sources, field observations, key informant interviews, focus group talks and individual interviews. The survey data were stratified into altitudes, coded and analysed using the Statistical Package for Social Sciences version 20 and the general linear model approach. Cross‐tabulation was used to examine the statistical variance of categorical data. Results: The presence of different feed resource types, distinct agro‐ecologies (p < 0.05) and crop residue accessibility were the major opportunities for dairy cattle production in the study district, but land scarcity, a lack of dry season forages and land degradation due to erosion were the major constraints for dairy cattle feed production. In the research district, the main feed resource–copying approaches were reducing the number of dairy animals, saving optional feeds and purchasing optional feeds. The total mean of dairy cow feed supply to tropical livestock unit in terms of dry matter (DM) production each year was 3.86 t of DM/HH/annual, with a negative feed balance of 8.09 t that varied with seasons and agro‐ecology (p < 0.05). Conclusions: According to the findings of this study, the low production of dairy cattle in the district is clearly related to the scarcity of feed resources. To address these issues, alternative feed production technologies should be implemented, such as farmers practising forage development on their own crop land and collecting crop residues during crop harvesting times and storing them under shed; the nutritive value of different types of fodder trees and shrubs should be further determined in the future and feed storage methods, particularly hay and silage, should be used when there are an abundance of feed resources available. [ABSTRACT FROM AUTHOR]

Bovine mastitis remains a major problem in the global dairy cattle industry. The acute invasion of udder by pathogens induces innate immune response as the first defence mechanism in subclinical and clinical mastitis. The aim of the study was to determine inflammatory and regulatory cytokines IL-2, IL-4, TGF-β1, IL-17A, beta-defensin 3 and IL-10 and their potential changes in milk of dairy cows with subclinical and clinical mastitis, and to compare the findings with healthy animals. Milk samples from 15 holstein Friesian breed cows were used in the study. Cows were divided into three groups based on their health status (5 healthy, 5 subclinical and 5 clinical animals). All samples were tested using immunohistochemistry to evaluate IL-2, IL-4, IL-10, IL17A, TGF-β1 and β-Def 3 proteins. Expression of all proteins was detected in all milk samples. High expression of IL-2, IL-4, IL17A, TGF-β1 was detected in healthy cows' milk and in milk of cows with subclinical and clinical mastitis. However, expression of IL-10 and β-Def 3 in milk samples of healthy cows was significantly higher compared to the milk of cows with subclinical and clinical mastitis (p <.001). IL-10 and β-Def 3 can be considered as informative biomarkers in diagnosis of subclinical and clinical mastitis. [ABSTRACT FROM AUTHOR]

Precision agriculture and the increasing automation efforts in animal husbandry requires continuous and complex monitoring of the animals. Rumen bolus sensors, which are cutting-edge pieces of technology and a rapidly developing research field, present an exceptional opportunity for monitoring the health status, physiological parameters, and estrus of the animals. The objective of this paper is to provide a comprehensive overview of the development process of a new sensor development. We address the issues of conceptual design, an overview of applicable sensor modalities, mechanical design, power supply design, applicable hardware solutions, applicable communication solutions and finally the sensor detection algorithms proved in field tests. In conclusion, we present a summary of the current opportunities in the field and provide an analysis of the foreseeable trends. [ABSTRACT FROM AUTHOR]

The objective of this meta-analysis was to quantify the potential of CH 4 -mitigating strategies in dairy cattle when accounting for the effects of treatment dose, dietary nutrient composition, and supplementation period. Data from 218 studies with dairy cattle published between 1963 to 2022 were reviewed. Individual CH 4 mitigation strategies selected for the analysis were algae (Asparagopsis spp.), 3-nitrooxypropanol, nitrate, lipids, plant secondary compounds, and direct-fed microbials (DFM). Response variables evaluated were daily CH 4 emission (g/d), CH 4 yield (g CH 4 /kg DMI), and CH 4 intensity (g CH 4 /kg milk yield [MY] and ECM). Relative mean difference between treatment and control means reported in the studies were calculated and used in the statistical analysis. Robust variance estimation method was used to analyze the effects of CH 4 mitigation strategies. Dose, forage-to-concentrate ratio (F:C), dietary concentrations of CP, ether extract (EE), NDF, ADF, and starch, and supplementation period were used as continuous explanatory variables. Data for algae supplementation were limited and responses to studied species were contrasting but, overall, Asparagopsis spp. effectively decreased daily CH 4 emission, CH 4 yield, and CH 4 intensities by 29.8 ± 4.6%, 23.0 ± 5.3%, 34.0 ± 4.3%, and 22.6 ± 7.3%, respectively. Supplementation of 3-nitrooxypropanol decreased daily CH 4 emission, yield, and intensity (per kg MY and ECM) by 28.2 ± 3.6%, 28.7 ± 2.8%, 29.2 ± 3.1%, and 31.8 ± 2.8%, respectively, compared with control. Decreasing dietary fiber (i.e., F:C, NDF, and ADF), whereas increasing dietary starch concentration increased the efficacy of 3-nitrooxypropanol at mitigating enteric CH 4 emission. Nitrate supplementation decreased CH 4 emission, yield, and intensity (per kg ECM) by 18.5% ± 1.9%, 17.6 ± 1.6%, and 13.0 ± 0.2%, respectively, compared with control. Efficacy of nitrate at mitigating enteric CH 4 yield and CH 4 intensity was positively associated with dose, and efficacy of nitrate at mitigating CH 4 yield was positively associated with dietary starch concentration. Lipid supplementation decreased CH 4 emission, yield, and intensities by up to 14.8 ± 2.3%, respectively, compared with control. Efficacy of lipids supplementation was positively associated with dietary EE, starch, and supplementation period, but negatively associated with dietary ADF concentration. Free oil supplementation tended to increase lipid efficacy by 31% at decreasing CH 4 emission, compared with control. Condensed tannins and plant-derived bioactive compounds decreased CH 4 yield by 11.3 ± 2.9% and 5.7 ± 2.5%, respectively, but oregano did not affect enteric CH 4 emission metrics in the current meta-analysis. Direct-fed microbials were not effective in mitigating enteric CH 4 emission variables. Data were limited to determine the effects of dietary nutrients and duration of supplementation on efficacy of Asparagopsis spp., plant secondary compounds and DFM. Overall, supplementation of the diet with Asparagopsis spp., 3-nitrooxypropanol, nitrate, and lipids were the most effective strategies for decreasing enteric CH 4 emission in dairy cattle. Variability in the efficacy of most CH 4 mitigation strategies can be partially explained by differences in treatment dose, dietary nutrient composition, and supplementation period. 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]

In vitro embryo production is one of the main reproductive techniques used in dairy Gyr cattle. In addition, linear type measures are well characterized and have been used in dairy Gyr breed selection for the last 4 decades. The estimation of genetic parameters for the number of aspirated oocytes and in vitro-produced embryos associated with the linear type measures would support genetic progress for animal breeding programs toward embryo production. This study aimed to estimate genetic parameters for aspirated oocytes, embryo in vitro production, and linear type traits, exploring the association between them. The repeatability model was applied to 14,251 ovum pick-up events from 1,916 Gyr donors. A subset of 604 donors from the same group had their body measurements taken. Single- and 2-trait analyses were carried out using the BLUPF90 family programs. Heritability estimates of 0.38, 0.34, and 0.20 were obtained for total oocytes, viable oocytes, and embryos, respectively, and the heritability of the linear type traits ranged from 0.22 to 0.40. High genetic correlations between total oocytes and viable oocytes (0.99), and between oocytes (total and viable) and embryos (0.83) were obtained. Low to high genetic (−0.07 to 0.92) and phenotypic (0.32–0.86) correlations were obtained between the linear type traits. Moreover, low phenotypic correlations (0.01–0.13) were observed for oocytes (total and viable) and embryos with the linear type traits, whereas low to moderate genetic correlations (0.07–0.42) were observed between the same traits, especially for ilium width (0.42), rump area (0.38), and hip height (0.33). Thus, selection for in vitro production is achievable in Gyr dairy cattle, and superior genetic progress is associated with the selection of oocytes (total and viable). Furthermore, the moderate genetic association between oocytes and embryos with linear type traits, especially ilium width suggests that progress on in vitro embryo production may be achieved by accessing these measurements. 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]

Because male and female effects on fertility must be considered, it may be difficult to achieve accurate and repeatable fertility predictions using only sperm characteristics given differences in breed, health, and season. Improving sperm quality after cryopreservation may be a method to reduce the male effect on the fertility outcome. This study was conducted using 2 different Certified Semen Service approved extenders, one containing plant-derived antioxidants, to assess cryopreserved sperm quality and determine pregnancy per AI (P/AI) in a commercial dairy farm. Beef bull ejaculates (n = 24 ejaculates, n = 4 bulls) were split and frozen in egg-yolk-TRIS (EYT) or GameteGuard-FB cryopreservation extenders. Frozen-thawed sperm was evaluated for sperm quality and used for insemination in dairy cows (n = 4,856). Improvement was shown in total and progressive motility, acrosome integrity, and reduction of DNA fragmentation at 0 and 3 h after thawing in sperm frozen in GameteGuard-FB when compared with the EYT extender. An overall 12.7% improvement in pregnancy per AI (P/AI) was observed when GameteGuard-FB (40.8%) was used for cryopreservation when compared with EYT (36.2%). More importantly, GameteGuard-FB frozen semen increased P/AI for first service by 19.5% (35.9% EYT and 42.9% GameteGuard-FB) and 45.0% was also observed at third service (31.3% EYT and 45.4% GameteGuard-FB). The use of GameteGuard-FB resulted in an average 40% P/AI among bulls. Taken together, the increase in cryopreserved sperm quality using GameteGuard-FB can be used to minimize the male effects on pregnancy outcomes in commercial dairy farms. 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 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]

Respiratory rate (RR) is an important indicator of the health and welfare status of dairy cows. In recent years, progress has been made in monitoring the RR of dairy cows using video data and learning methods. However, existing approaches often involve multiple processing modules, such as region of interest (ROI) detection and tracking, which can introduce errors that propagate through successive steps. The objective of this study was to develop an end-to-end computer vision method to predict RR of dairy cows continuously and automatically. The method leverages the capabilities of a state-of-the-art Transformer model, VideoMAE, which divides video frames into patches as input tokens, enabling the automated selection and featurization of relevant regions, such as a cow's abdomen, for predicting RR. The original encoder of VideoMAE was retained, and a classification head was added on top of it. Further, the weights of the first 11 layers of the pre-trained model were kept, whereas the weights of the final layer and classifier were fine-tuned using video data collected in a tiestall barn from 6 dairy cows. Respiratory rates measured using a respiratory belt for individual cows were serving as the ground truth (GT). The evaluation of the developed model was conducted using multiple metrics, including mean absolute error (MAE) of 2.58 breaths per minute (bpm), root mean squared error (RMSE) of 3.52 bpm, root mean squared prediction error (RMSPE; as a proportion of observed mean) of 15.03%, and Pearson r of 0.86. Compared with a conventional method involving multiple processing modules, the end-to-end approach performed better in terms of MAE, RMSE, and RMSPE. These results suggest the potential to implement the developed computer vision method for an end-to-end solution, for monitoring RR of dairy cows automatically in a tiestall setting. Future research on integrating this method with other behavioral detection and animal identification algorithms for animal monitoring in a freestall dairy barn can be beneficial for a broader application. 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]

Lameness in dairy cattle is a clinical sign of impaired locomotion, mainly caused by painful foot lesions, compromising the US dairy industry's economic, environmental, and social sustainability goals. Combining technology and on-farm data may be a more precise and less labor-intensive lameness detection tool, particularly for early detection. The objective of this observational study was to describe the association between average weekly autonomous camera-based (AUTO) locomotion scores and hoof trimming (HT) data. The AUTO data were collected from 3 farms from April 2022 to March 2023. Historical farm HT data were collected from March 2016 to March 2023 and used to determine cow lesion history and date of HT event. The HT events were categorized as a regular HT (TRIM; n = 2,290) or a HT with a lesion recorded (LESION; n = 670). Events with LESION were subcategorized based on lesion category: digital dermatitis (DD; n = 276), sole ulcer (SU; n = 79), white line disease (WLD; n = 141), and other (n = 174). The data also contained the leg of the LESION, classified as front left (FL; n = 54), front right (FR; n = 146), rear left (RL; n = 281), or rear right (RR; n = 183) leg with 6 events missing the leg. Cows' HT histories were classified as follows: cows with no previous recorded instance of any lesion were classified as TRIM0 (n = 1,554). The first instance of any hoof lesion was classified as LESION1 (n = 238). This classification was retained until a subsequent TRIM occurred—recorded as TRIM1 (n = 632). The next unique instance of any lesion following a TRIM1 was classified as LESION2 (n = 86). Any LESION events occurring after LESION1 or LESION2 without a subsequent TRIM were considered a hoof lesion recurrence and classified as LESIONRE1 (n = 164) and LESIONRE2 (n = 22), respectively. TRIM events after LESION2 or LESION2RE (n = 104) or LESION events after LESIONRE1 or LESIONRE2 were classified as LESION_OTHER (n = 160). The AUTO scores from −28 to −1 d prior to the HT event were summarized into weekly scores and included if cows had at least 1 observation per week in the 4 wk before the event. For all weeks, LESION cows had a higher median AUTO score than TRIM cows. Cows with TRIM0 had the lowest and most consistent median weekly score compared to LESION and other TRIM classifications. Before HT cows with TRIM0 and TRIM1, both had median score increases of 1 across the 4 wk, whereas the LESION categories had an increase of 4 to 8. Scores increased with each subsequent LESION event compared to the previous LESION event. Cows with SU lesions had the highest median score across the 4 wk, WLD had the largest score increase, and DD had the lowest median score and score increase. When grouping a LESION event by leg the hoof lesion was found on, the AUTO scores for 4 groups displayed comparable median values. Due to the difference between TRIM and LESION events, this technology shows potential for the early detection of hoof lesions. 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 economic burden of diseases and reproductive inefficiency in dairy cattle is evident and has been quantified. Dairy diseases and reproductive inefficiency are however associated with other issues as well, including animal welfare, environmental pressure, and public health risks. Quantifying these other issues is becoming important to help farmers make decisions. Quantification of the noneconomic burdens of diseases and reproductive inefficiency is rare and lacks an overview of approaches and metrics. The first aim of this paper is to provide trends for associating diseases and reproductive inefficiency with economic and noneconomic burdens of disease. The second aim is to provide a review of approaches and metrics used to quantify the noneconomic burdens of disease and reproductive inefficiency. For the economic burden of diseases and reproductive performance, only an overview of the approaches used to quantify the burden is provided. The final aim is to propose approaches and metrics for future quantification of noneconomic burdens caused by individual diseases. A literature search was conducted in Web of Science to identify scientific articles on mastitis, lameness, metabolic disorders, and reproductive inefficiency in dairy cows. The search was restricted to articles published between January 1, 2010 and December 31, 2022 and resulted in 7,565 articles. The total number of articles that mentioned the economic, animal welfare, public health, and environmental burden was 1,253, 428, 291, and 77, respectively. An increase in the percentage of articles mentioning the economic, animal welfare, and public health burden was observed between 2010 and 2022. Despite the 2,049 articles that mentioned one of the burdens, the results showed that approximately 10% of the articles quantified one or more of these burdens. The economic burden of diseases and reproductive inefficiency has been quantified in 154 articles and very few articles quantified the noneconomic burdens (9 articles for environment, 29 articles for public health, and 2 articles for animal welfare). Eleven articles were identified that quantified multiple burdens, and in all these studies the economic burden was combined with a noneconomic burden through a modeling approach (mainly simulation). We propose to link the noneconomic burdens to biological simulation models, and thus develop bioburden simulation models. Well-established approaches and metrics can be used to quantify economic, environmental, and public health burdens. For the economic impact, costs per cow per year can be assessed. A life cycle assessment can be performed for environmental impact and the public health impact can be assessed by a defined daily dose for antimicrobial use and disability-adjusted life years for zoonotic diseases. Regarding animal welfare, approaches and metrics to quantify the welfare impact of a diseased animal are not well established. For animal welfare, we propose a welfare-adjusted life years approach. The mentioned approaches and metrics are a proposal, and it is up to the scientific community to use them or, based on empirics and research experience, propose changes so that we will end up with robust approaches and metrics that enable us to compare research results and provide more evidence for animal health decision makers. 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 apparent absorption of copper (Cu) in ruminants is low, with between 0.01 and 0.07 g/g absorbed from sources such as copper oxide (CuO) under typical feeding conditions, resulting in high levels of excretion. Improving the bioavailability of Cu could reduce the supplemental amount required to maintain Cu status and reduce excretion, particularly in the presence of dietary antagonists such as sulfur (S) and molybdenum (Mo). The objective of our study was to determine the Cu status of cows when fed nanoparticle CuO coated with Lys compared with conventional CuO when fed without or in combination with antagonists to Cu absorption (S and Mo) in the diet of dairy cows. Fifty-six multiparous Holstein-Friesian cows that were 48 d ± 17.2 (mean ± SD) postcalving and yielding 41 ± 6.4 kg of milk per day were used in a 2 × 2 factorial design. The 4 treatment groups were: CuO (O-), CuO with added antagonists (O+), nano CuO with a lysine coating (N-), and nano CuO with a Lys coating with added antagonists (N+), fed for 16 wk. We formulated the diets to contain ∼17 mg of Cu/kg DM, and diets with antagonists contained an additional 1 g of S/kg DM and 6 mg of Mo/kg DM, with Lys added to O- and O+ to provide the same daily supply as N- and N+. Blood samples were collected at wk 0, 2, 4, 6, 10, and 16, and liver biopsy samples at wk 0 and 16. We found no effect of dietary treatment on DMI, milk yield, live weight, or BCS, with mean values of 23.3 kg/d, 40.1 kg/d, 646 kg, and 2.68, but milk SCC was higher in cows fed conventional compared with nano CuO, or added compared with no added antagonists. We also found no effect of treatment on blood activity of gamma glutamyl transferase, superoxide dismutase, or ceruloplasmin, hematology profile, or plasma Cu and iron concentration. We found that plasma Mo concentration was increased from 0.36 µmol/L in cows fed O- or N- to 0.80 µmol/L in those receiving O+ or N+. Additional dietary antagonists also decreased the concentration of Cu in the liver of cows fed conventional CuO (C+) over the study period by 1.3 mg/kg DM per day, but in cows fed dietary antagonists and nano CuO coated with Lys (N+), liver Cu concentration was increased by 1.1 mg/kg DM per day. Our study is the first to demonstrate that reducing the particle size of CuO into the nano scale with a lysine coating improves the bioavailability of CuO in the presence of dietary antagonists in dairy cattle, and we did not observe any negative effects on performance or health. 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]

Cull cows from dairy farms in the United States account for 10% of the beef market; however, few studies have evaluated the effects of crossbreeding on reasons for disposal and cull value of dairy cows. The objective of the study was to compare reasons for disposal and cull cow value of Holstein and crossbred cows (n = 1,292) in an experimental dairy herd at the University of Minnesota West Central Research and Outreach Center (Morris, MN). Cows were Holstein (n = 272), 1964 genetic control Holstein (n = 161), 3-breed crossbred cows (n = 538) composed of the Montbéliarde, Viking Red, and Holstein (MVH) breeds, and 3-breed crossbred cows (n = 321) composed of the Normande, Jersey, and Viking Red (NJV) breeds. The 1964 genetic control Holstein cows originated from a design initiated at the University of Minnesota for comparison of the 1964 Holstein and contemporary Holstein cows selected for production across time. Records spanned from January 2010 to December 2023. Reasons for disposal were recorded in PCDart Herd Management Software, and cull value and body weight were obtained from receipts from livestock cull markets. For all cows, the primary reasons for disposal were as follows: reproduction (44.4%), mastitis (18%), other reasons (14.6%), death (10.3%), dairy purposes (8.4%), and low production (4.3%). Independent variables for statistical analysis of cull value were the fixed effects of body weight at time of culling, DIM at culling (0–49 DIM, 50–99 DIM, 100–149 DIM, 150–199 DIM, 200–249 DIM, 250–299 DIM, 300–350 DIM, and >350 DIM), year (2010–2023), season (spring, summer, autumn, winter), parity (1, 2, 3, 4, 5+), primary reason for culling, breed group, and sire breed group nested within breed group. Least squares means for body weight at culling was 558 kg for Holsteins, 543 kg for 1964 Holsteins, 551 kg for MVH crossbred cows, and 499 kg for NJV crossbred cows. For the analysis across time, 2014 had the highest cull value ($1,126.98), and 2020 had the lowest gross cull value ($515.21). Cows culled at greater than 300 DIM had the highest cull value and cows culled at less than 50 DIM had the lowest cull value. Cows culled during the spring and summer had higher cull value compared with cows culled during the autumn and winter. The Holstein cows ($730.04) had lower gross value compared with 1964 Holsteins ($804.38) cows and MVH ($767.39) cows. The NJV ($771.39) cows were not different from crossbreds sired by Montbéliarde, Viking Red, and Holstein bulls. Results for comparisons of breed group are from one experimental herd, so inferences to the wider dairy cow population should be undertaken with caution. In summary, dairy producers may receive greater cull value from crossbred cows compared with Holstein 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]

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]

Dairy cattle health traits are paramount from a welfare and economic viewpoint, and modern breeding programs therefore prioritize the genetic improvement of these traits. Estimated breeding values for health traits are published as the probability of animals staying healthy. They are obtained using threshold models, which assume that the observed binary phenotype (i.e., healthy or sick) is dictated by an underlying normally distributed liability exceeding or not exceeding a threshold. This methodology requires significant computing time and faces convergence challenges, as it implies a nonlinear system of equations. Linear models have more straightforward computations and provide a robust approximation to threshold models; thus, they could be used to overcome these challenges. However, linear models yield estimated breeding values on the observed scale, requiring an approximation to the liability scale analogous to that from threshold models to later obtain the estimated breeding values on the probability scale. In addition, the robustness of the approximation of linear to threshold models depends on the amount of information and the incidence of the trait, with extreme incidence (i.e., ≤5%) deviating from optimal approximation. Our objective was to test a transformation from the observed to the liability, and then to the probability scale, in the genetic evaluation of health traits with moderate and very low (extreme) incidence. Data comprised displaced abomasum (5.1 million), ketosis (3.6 million), lameness (5 million), and mastitis (6.3 million) records from a Holstein population with a pedigree of 6 million animals, of which 1.7 million were genotyped. Univariate threshold and linear models were performed to predict breeding values. The agreement between estimated breeding values on the probability scale derived from threshold and linear models was assessed using Spearman rank correlations and comparison of estimated breeding values distributions. Correlations were at least 0.95, and estimated breeding value distributions almost entirely overlapped for all the traits but displaced abomasum, the trait with the lowest incidence (2%). Computing time was ∼3 times longer for threshold than for linear models. In this Holstein population, the approximation was suboptimal for a trait with extreme incidence (2%). However, when the incidence was ≥6%, the approximation was robust, and its use is recommended along with linear models for analyzing categorical traits in large populations to ease the computational burden. 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]

Our objective was to validate the possibility of detecting SARA from milk Fourier transform mid-infrared spectroscopy estimated fatty acids (FA) and machine learning. Subacute ruminal acidosis is a common condition in modern commercial dairy herds for which diagnosis remains challenging due to its symptoms often being subtle, nonexclusive, and not immediately apparent. This observational study aimed at evaluating the possibility of predicting SARA by developing machine learning models to be applied to farm data and to provide an estimated portrait of SARA prevalence in commercial dairy herds. A first dataset, composed of 488 milk samples from 67 cows (initial DIM = 8.5 ± 6.18; mean ± SD) from 7 commercial dairy farms and their corresponding SARA classification (SARA+ if rumen pH <6.0 for 300 min, otherwise SARA−) was used for the development of machine learning models. Three sets of predictive variables (milk major components [MMC], milk FA [MFA], and MMC combined with MFA [MMCFA]) were submitted to 3 different algorithms, namely elastic net (EN), extreme gradient boosting, and partial least squares, and evaluated using 3 different scenarios of cross-validation. The accuracy, sensitivity, and specificity of the resulting 27 models were analyzed using a linear mixed model. Model performance was not significantly affected by the choice of algorithm. Model performance was improved by including FA estimations (MFA and MMCFA as opposed to MMC alone). Based on these results, 1 model was selected (algorithm: EN; predictive variables: MMCFA; 60.4%, 65.4%, and 55.3% of accuracy, sensitivity, and specificity, respectively) and applied to a large dataset comprising the first test-day record (milk major components and FA within the first 70 DIM of 211,972 Holstein cows [219,503 samples]) collected from 3,001 commercial dairy herds. Based on this analysis, the within-herd SARA prevalence of commercial farms was estimated at 6.6 ± 5.29% ranging from 0% to 38.3%. A subsequent linear mixed model was built to investigate the herd-level factors associated with higher within-herd SARA prevalence. Milking system, proportion of primiparous cows, herd size, and seasons were all herd-level factors affecting SARA prevalence. Furthermore, milk production was positively associated with SARA prevalence, and milk fat yield was negatively associated. Due to their moderate levels of accuracy, the SARA prediction models developed in our study, using data from continuous pH measurements on commercial farms, are not suitable for diagnostic purposes. However, these models can provide valuable information at the herd level. 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]

This study was conducted to determine if the decreased MP supply predicted by the NRC (2001) when canola meal (CM) substitutes soybean meal (SBM) was supported by direct measurement of net portal absorption of AA or energy-yielding nutrients, plus the effect of the type of forage in CM-based rations. Nine Holstein cows with indwelling catheters in splanchnic blood vessels, 8 also with a ruminal cannula, were used to examine the effects of protein source in corn silage-based diets, comparing SBM versus CM, and forage source in CM-based diets, comparing corn versus grass silage. The cows were allocated to a triple 3 × 3 Latin square design with 21-d periods. The 3 experimental diets, formulated to be isoenergetic and isonitrogenous, were based on: (1) SBM and corn silage (SoCo); (2) CM and corn silage (CaCo) and (3) CM and cool-season grass silage (CaGr). Averages of intake, milk yield, and milk composition of the last 3 d of each period were used for statistical analyses. On d 21 of each period, 6 sets of arterial, portal, hepatic, and mammary blood samples and 2 ruminal fluid samples were collected. On d 12 of period 2, the protein sources were incubated in nylon bags to determine 16-h ruminal disappearance of DM and N and to obtain 16-h residues. Finally, 5 d after the completion of the Latin square design, the mobile bag technique was used to determine DM and N intestinal disappearance of the 16-h residues of SBM and CM. Pre-planned contrasts were used to compare the effect of the protein source in cows fed corn silage (i.e., SoCo vs. CaCo) and the effect of forage in cows fed CM (i.e., CaCo vs. CaGr). Data of the cow without a rumen canula could not be used because of health problem. In corn silage-based diets, substitution of SBM by CM tended to increase milk (6%) and milk fat (7%) yields. The 8% higher ruminal N disappearance and the 19% decreased MP supply from RUP predicted by NRC (2001) were not supported by the 25% decrease in ruminal ammonia concentration, similar net portal absorption of AA (except 22% higher for Met), and the 14% decrease in urea hepatic removal when CM substituted SBM. Ruminal incubation of CM in nylon bags does not appear suitable for adequate determination of the rumen by-pass of a protein source such as CM. Inclusion of grass silage rather than corn silage in CM-based diets tended to increase milk (6%) and increased milk lactose (8%) yields. Neither protein nor forage source resulted in variations of metabolism of energy-yielding nutrients that could explain observed increments in cow performance. The present study indicates no decreased AA availability when CM substitutes SBM. Therefore, substitution of SBM by CM in diets based on corn silage and CM in corn- or grass silage diets can be used successfully in high producing 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]

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]

The early lactation period in dairy cows is characterized by complex interactions among energy balance (EB), disease, and alterations in metabolic and inflammatory status. The objective of this study was to cluster cows based on EB time profiles in early lactation and investigate the association between EB clusters and inflammatory status, metabolic status, oxidative stress, and disease. Holstein-Friesian dairy cows (n = 153) were selected and monitored for disease treatments during wk 1 to 6 in lactation. Weekly EB was calculated based on energy intake and energy requirements for maintenance and milk yield in wk 1 to 6 in lactation. Weekly plasma samples were analyzed for metabolic variables in wk 1 to 6, and inflammatory and oxidative stress variables in wk 1, 2, and 4 in lactation. Liver activity index (LAI) was computed from plasma albumin, cholesterol, and retino-binding protein concentration. First, cows were clustered based on time profiles of EB, resulting in 4 clusters (SP: stable positive; MN: mild negative; IN: intermediate negative; SN: severe negative). Cows in the SN cluster had higher plasma nonesterified fatty acids and BHB concentrations, compared with cows in the SP cluster, with the MN and IN clusters being intermediate. Cows in the SN cluster had a higher milk yield, lower DMI in wk 1, lower insulin concentration compared with cows in the SP cluster, and lower glucose and IGF-1 concentration compared with cows in the SP and MN clusters. Energy balance clusters were not related to plasma haptoglobin, cholesterol, albumin, paraoxonase, and LAI. Second, cows were grouped based on health status: IHP, cows with treatment for inflammatory health problem (endometritis, fever, clinical mastitis, vaginal discharge or retained placenta); OHP, cows with no IHP but treatment for other health problem (milk fever, cystic ovaries, claw and leg problems, rumen and intestine problems, or other diseases); and NHP, cows with no treatments, in the first 6 wk after calving. Energy balance was not different among health status groups. The IHP cows had lower nonesterified fatty acids and greater insulin concentration in plasma compared with OHP cows. The IHP cows had lower plasma albumin concentration, lower LAI, and higher haptoglobin concentration compared with OHP and NHP. Overall, EB time profiles were associated with the metabolic status of dairy cows in early lactation, but were only limitedly related to markers of inflammation and oxidative stress status. Inflammatory and metabolic status were related to disease events in early lactation and caused prolonged effects on liver metabolism. 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 transition from pregnancy to lactation is critical in dairy cows. Among others, dairy cows experience a metabolic stress due to a large change in glucose and lipid metabolism. Recent studies revealed that bile acids (BA), other than being involved in both the emulsification and solubilization of fats during intestinal absorption, can also affect the metabolism of glucose and lipids, both directly or indirectly by affecting the gut microbiota. Thus, we used untargeted and targeted metabolomics and 16S rRNA gene sequencing approaches to investigate the concentration of plasma metabolites and BA, the composition of the rectum microbial community, and assess their interaction in transition dairy cows. In Experiment 1, we investigated BA and other blood parameters and gut microbiota in dairy cows without clinical diseases during the transition period, which can be seen as well adapted to the challenge of changed glucose and lipid metabolism. As expected, we detected an increased plasma concentrations of BHB and nonesterified fatty acids (NEFA) but decreased concentrations of glucose, cholesterol, and triglycerides (TG). Untargeted metabolomic analysis of the plasma revealed primary BA biosynthesis was one of the affected pathways, and was consistent with the increased concentration of BA in the plasma. A correlation approach revealed a complex association between BA and microbiota with the host plasma concentration of glucose and lipid metabolites. Among BA, chenodeoxycholic acid derivates such as glycolithocholic acid, taurolithocholic acid, lithocholic acid, taurochenodeoxycholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites (such as glucose, TG, and NEFA). In Experiment 2, we investigated early postpartum dairy cows with or without hyperketonemia (HPK). As expected, HPK cows had increased concentration of NEFA and decreased concentrations of glucose and triglycerides. The untargeted metabolomic analysis of the plasma revealed that primary BA biosynthesis was also one of the affected pathways. Even though the BA concentration was similar among the 2 groups, the profiles of taurine-conjugated BA changed significantly. A correlation analysis also revealed an association between BA and microbiota with the concentration in plasma of glucose and lipid metabolites (such as BHB). Among BA, cholic acid and its derivates such as taurocholic acid, tauro α-muricholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites. Our results indicated an association between BA, intestinal microbe, and glucose and lipid metabolism in transition dairy cows. These findings provide new insight into the adaptation mechanisms of dairy cows during the transition period. 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 aims of this research were to evaluate how prolonged feeding of a high-concentrate diet affects the ruminal degradation kinetics of fiber and starch, and to evaluate the effects of the high-concentrate diet on apparent total-tract nutrient digestibility in dairy cows. We also investigated the dysbiotic effects and the remodeling of the hindgut microbiome with prolonged high-concentrate feeding. Nine Holstein cows were used in 2 experimental periods; in each period, cows were first fed a 100% forage diet for 1 wk, followed by stepwise adaptation during one week to a high-concentrate (HC) diet (65% concentrate), which was then fed for 4 consecutive weeks. The kinetics of in situ ruminal degradability of grass silage (DM and NDF), corn grain and wheat grain (DM and starch), as well as the apparent total-tract nutrient digestibility were evaluated in the forage feeding and in wk 4 on the HC diet. Whereas the hindgut microbiome and fermentation profile were evaluated on a weekly basis. Regarding the in situ ruminal degradability due to grain type, the rate of degradation of the potentially degradable fraction and the effective rumen degradability of wheat grain were greater compared with corn grain. The in situ ruminal degradability of NDF decreased with the HC diet. However, the apparent total-tract digestibility of CP, fat, starch, NDF, ADF, and NFC increased with the HC diet compared with forage feeding. In addition, the HC diet increased the concentration of short-chain fatty acids in the hindgut, lowering fecal pH by 0.6 units, which correlated positively with microbial α diversity. This resulted in lower α diversity with the HC diet; however, α diversity (number of amplicon sequence variants) showed recovery in wk 3 and 4 on HC; in addition, microbial β diversity did not change from wk 2 onward on the HC diet. Two microbial enterotypes were identified: one for the forage diet with abundance of Akkermansia and Anaerosporobacter , and another enterotype for the HC diet with enrichment in Bifidobacterium and Butyrivibrio. Overall, results show that major microbial shifts and hindgut dysbiosis occurred in wk 1 on the HC diet. However, the hindgut microbial diversity of cows adapted after 3 wk of consuming the starch-rich ration. Thus, feeding the HC diet impaired fiber degradation in the rumen, but increased apparent total-tract nutrient digestibility. Likely, the forage diet contained less digestible NDF than the HC diet due to greater inclusion of forages with lower NDF digestibility and lower inclusion of more digestible nonforage NDF. Results also suggest that the adaptation of the hindgut microbial diversity of cows observed 3 weeks after the diet transition likely contributed to enhance total-tract nutrient digestibility. 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]

Factors contributing to variations in the quality and microbiota of ensiled forages and in bulk tank microbiota in milk from cows fed different forages were investigated. Nutritional quality, fermentation parameters and hygiene quality of forage samples and corresponding bulk tank milk samples collected in 3 periods from 18 commercial farms located in northern Sweden were compared. Principal coordinates analysis revealed that the microbiota in forage and bulk milk, analyzed using 16S rRNA gene-based amplicon sequencing, were significantly different. The genera Lactobacillus , Weissella , and Leuconostoc dominated in forage samples, whereas Pseudomonas , Staphylococcus , and Streptococcus dominated in bulk milk samples. Forage quality and forage-associated microbiota were affected by ensiling method and by use of silage additive. Forages stored in bunker and tower silos (confounded with use of additive) were associated with higher levels of acetic and lactic acid and Lactobacillus. Forage ensiled as bales (confounded with no use of additive) was associated with higher DM content, water-soluble carbohydrate content, pH, yeast count, and the genera Weissella , Leuconostoc , and Enterococcus. For bulk tank milk samples, milking system was identified as the major factor affecting the microbiota and type of forage preservation had little effect. Analysis of common amplicon sequence variants (ASV) suggested that forage was not the major source of Lactobacillus found in bulk tank milk. 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 uptake of AA in mammary tissues is affected by prolactin (PRL). To investigate whether PRL-induced AA uptake is involved in l -type AA transporter 1 (LAT1), we analyzed the changes of AA in the medium of dairy cow mammary epithelial cells in the presence of PRL or PRL plus heptanecarboxylic acid (BCH), an inhibitor of LAT1. Then Western blot and luciferase assay were used to detect the regulation mechanism of PRL on LAT1 expression and function. Our results showed that Thr, Val, Met, Ile, Leu, Tyr, Lys, Phe, and His are LAT1 substrates and could be transported into mammary epithelial cells via LAT1. PRL stimulation increased the uptake of most AA into mammary epithelial cells of dairy cows, however, inhibition of LAT1 transport activity reduced PRL-induced AA uptake, suggesting that the effect of PRL on AA transport depends on LAT1 expression and function. PRL stimulation upregulated LAT1 expression and plasma membrane location not only in dairy cow mammary epithelial cells, but also in mouse mammary epithelial cell line HC11. Western blot showed that PI3K-AKT-mTOR signaling could be activated in PRL-stimulated mammary epithelial cells. Treatment of cells with LY294002 decreased PI3K-AKT-mTOR activation, as well as LAT1 expression, that in turn decreased milk protein synthesis. Luciferase assay showed PRL treatment increased the promoter activity of LAT1 promoter fragment −419 to −86 bp. Treatment of cells with LY294002, an inhibitor of PI3K, or SC79, an activator of AKT abolished or promoted the transcriptional activity of this promoter fragment in the presence of PRL. These results suggested that the −419 to −86 bp fragment of LAT1 promoter mediates the action of PI3K-AKT-mTOR signaling on LAT1 transcription in mammary epithelial cells of dairy cows, which in turn increased LAT1 expression and AA uptake. 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]