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Recent studies have shown that cows with subclinical hypocalcemia (SCH) at 4 d in milk (DIM), regardless of their blood Ca concentration before that time point, suffer from an increased early-lactation disease risk and reduced milk yield, whereas cows experiencing a transient reduction in blood Ca that regain normocalcemia by 4 DIM are at a reduced risk of disease and have greater milk yields. With a goal of improving outcomes for dyscalcemic cows with SCH at 4 DIM, our primary objective was to assess the effect of a herd-level oral Ca bolus strategy that delayed supplementation to 24 and 48 h postpartum on productive performance of multiparous Holstein cows. Our secondary objectives were to assess the effects of delayed Ca bolus supplementation on blood Ca concentration, disease incidence within 30 DIM, and pregnancy risk to first service. At calving, multiparous cows on a single commercial dairy farm in Iran were randomly assigned to 1 of 3 treatment groups: (1) control, no Ca bolus administration (CON; n = 95); (2) traditional bolus, one Ca bolus administered immediately following calving and a second Ca bolus administered 24 h after calving (TRD, n = 102); or (3) experimental bolus, one Ca bolus administered 24 h after calving with a second Ca bolus administered 48 h after calving (EXP, n = 99). Blood samples were collected at 0, 24, 48, 72, and 96 h, and 7 d after parturition, with sampling occurring before bolus administration for the TRD (0 and 24 h) and EXP (24 and 48 h) groups. A general linear mixed model was created to analyze the change milk yield over the first 4 monthly tests and serum Ca concentrations over 7 DIM. Given the lack of disease events diagnosed within 30 DIM, no statistical analysis was conducted for this outcome. The effect of treatment group on risk of pregnancy to first service was assessed using Poisson regression. The incidence of dyscalcemia within CON cows was 72%. We found no difference in mean monthly milk yield among treatment groups across the first 4 tests, with an average monthly production of 51.8 ± 8.8 kg/d for CON cows, 52.5 ± 8.7 kg/d for TRD cows, and 51.8 ± 8.7 kg/d for EXP cows. Mean blood Ca concentration also did not differ across 7 DIM among treatment groups and was 2.04 mmol/L [95% confidence interval (CI) = 2.00 to 2.07 mmol/L] for CON cows, 2.06 mmol/L (95% CI = 2.03 to 2.09 mmol/L) for TRD cows, and 2.09 mmol/L (95% CI = 2.05 to 2.12 mmol/L) for EXP cows. The risk of pregnancy to first service was numerically greater for CON than TRD and EXP cows but not statistically different; however, our study was underpowered for this outcome. Under the conditions of our study, our findings suggest that delaying oral Ca bolus supplementation to 24 and 48 h postpartum has no effect on milk production across the first 4 monthly tests. [ABSTRACT FROM AUTHOR]

Simple Summary: Bovine fatty liver syndrome is a metabolic disorder in transition dairy cows that has been associated with adverse consequences such as lower milk production and fertility. Fatty liver syndrome is difficult to monitor and diagnose in applied practice and research settings because it requires a liver tissue biopsy to determine liver triglyceride content. This study aimed to develop and validate a panel of blood metabolite, protein, and mineral biomarkers as a less invasive and more accessible tool to assess liver triglyceride content. We investigated a variety of panels using blood measurements from a single timepoint or multiple timepoints, as well as different combinations of biomarkers based on their perceived accessibility. Both the single and multiple timepoint biomarker panels accurately classified cows with high liver triglyceride content (top 33.3% vs. lower 66.7%), but accuracy was lower for classifying cows with or without maximum liver triglyceride in the top 50% or top 66.7% of liver triglyceride content. We suggest that the blood biomarker models predicting high triglyceride content may be useful for monitoring fatty liver in research and applied practice, as well as enable larger scale research studies investigating fatty liver in dairy cows. Bovine fatty liver syndrome (bFLS) is difficult to diagnose because a liver tissue biopsy is required to assess liver triglyceride (TG) content. We hypothesized that a blood biomarker panel could be a convenient alternative method of liver TG content assessment and bFLS diagnosis. Our objectives were to predict liver TG using blood biomarker concentrations across days in milk (DIM; longitudinal, LT) or at a single timepoint (ST; 3, 7, or 14 DIM), as well as different biomarker combination based on their perceived accessibility. Data from two separate experiments (n = 65 cows) was used for model training and validation. Response variables were based on the maximum liver TG observed in 1 and 14 DIM liver biopsies: Max TG (continuous), Low TG (TG > 13.3% dry matter; DM), Median TG (TG > 17.1% DM), and High TG (TG > 22.0% DM). Model performance varied but High TG was well predicted by sparse partial least squares—discriminate analysis models using LT and ST data, achieving balanced error rates ≤ 15.4% for several model variations during cross-validation. In conclusion, blood biomarker panels using 7 DIM, 14 DIM, or LT data may be a useful diagnostic tool for bFLS in research and field settings. [ABSTRACT FROM AUTHOR]

Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health. [ABSTRACT FROM AUTHOR]

Restricted dietary P supply to transition dairy cows has recently been reported to beneficially affect the Ca balance of periparturient cows. The objective of the present study was to determine whether this effect on the Ca balance can be reproduced when limiting the P-restricted feeding to the last 4 wk of gestation. A total of 30 dairy cows in late pregnancy were randomly assigned to a dry cow diet with either low or adequate P content (0.16 and 0.30% P in DM, respectively) to be fed in the 4 wk before expected calving. After calving, all cows received the same lactating cow ration with adequate P content (0.46% P in DM). Blood was collected daily from 4 d antepartum until calving, at calving (d 0), 6 and 12 h after calving (d +0.25 and d +0.5, respectively) and on days +1, +2, +3, +4 and +7 relative to calving. Blood gas analyses were conducted to determine the concentration of ionized Ca in whole blood ([Ca2+]), and plasma was assayed for concentrations of inorganic phosphorus ([Pi]), total calcium, parathyroid hormone ([PTH]), 1,25-dihydroxyvitamin D ([1,25-(OH) 2 D 3 ]), and CrossLaps ([CTX]), a biomarker for bone resorption (Immunodiagnostic Systems GmbH). Repeated-measures ANOVA was conducted to study treatment, time, and lactation number effects. The mean [Ca2+] in P-deprived cows remained above the threshold of 1.10 mmol/L throughout the study, and values were higher compared with cows on adequate P supply between d 0 and d +2 and on d +4. The [Ca2+] differed between treatments at the sampling times d 0, d +0.25, d +0.5, d +2, and d +4. Plasma [PTH] and [1,25-(OH) 2 D 3 ] did not differ between treatments, but P-deprived cows had greater [CTX] than cows with adequate P supply at d +1, d +2, and d +7. These results indicate that restricted dietary P supply to during the last 4 wk of the dry period improves the Ca homeostasis of these cows in the first days of lactation, an effect that seems to be primarily driven by increased bone tissue mobilization. [ABSTRACT FROM AUTHOR]

An experiment was conducted to determine the effects of low and high metabolizable protein (MP) diets when fed for ad libitum and controlled intake during the prepartum period on postpartum lactation performance and feeding behavior of dairy cows. Thirty-six multiparous Holstein cows were blocked by parity, expected calving date, and previous lactation milk yield at −21 d relative to expected calving and were randomly assigned to 1 of 4 close-up period dietary treatments providing low MP (LMP) or high MP (HMP) diets with controlled intake (CNI) or ad libitum intake (ALI). The concentrations of MP were 65 and 90 g/kg dry matter for LMP and HMP diets, respectively, whereas intake was controlled to supply 100 and 160% of the NRC (2001) energy requirements for CNI and ALI groups, respectively. The concentration of net energy for lactation (NE L) in the treatment diets was 1.50 Mcal/kg. All cows were fed a similar lactation diet after calving (1.50 Mcal/kg of NE L and 83.3 g/kg of MP). The HMP diet increased dry matter intake during the first 3 wk and tended to increase dry matter intake over the 9 wk of lactation. Meal size and eating rate increased in the ALI cows during the prepartum period. Meal frequency increased with the HMP diet during the postpartum period. Milk yield increased by 15.2% with the HMP diet over the 9 wk of lactation. The HMP diet increased energy-corrected milk (ECM) yield in CNI versus ALI cows, whereas the LMP diet increased ECM yield in ALI versus CNI cows over the 9 wk of lactation. The increase in ECM yield of LMP-ALI versus LMP-CNI cows was supported by greater body condition loss and serum β-hydroxybutyrate over the 9 wk of lactation. Taken together, these data indicate that prepartum controlled intake of a high protein diet can provide the benefits of both strategies. [ABSTRACT FROM AUTHOR]

Isoprostanes (isoP) are formed during conditions of oxidative stress (OS) through the oxidation of cell membrane fatty acids. Different classes of isoP are formed depending on the fatty acid being oxidized but the biological activity of these molecules in innate immune cells is poorly understood. Thus, the objective of this study was to compare in vitro the effects of F2- and F3-isoP on neutrophil microbicidal functions. We isolated neutrophils from 6 dairy cows and incubated them for 8 h at various concentrations of F2- and F3-isoP. Then, microbicidal function was assessed in terms of phagocytosis, respiratory burst, myeloperoxidase activity, and extracellular trap formation. In vitro supplementation with F3-isoP enhanced microbicidal capabilities whereas supplementation with F2-isoP decreased or did not impact these microbe killing functions. Hence, favoring the production of F3- over F2-isoprostanes may be a strategy to augment neutrophils' functional capacity during OS conditions. This should be tested in vivo. • F2-isoprostane decreased neutrophil microbicidal capabilities. • F3-isoprostane increased neutrophil microbicidal capabilities. • There was no dose-dependent effect noted for F2- or F3-isoprostane. • Favoring the production of F3- over F2-isoprostane during times of oxidative stress could ameliorate neutrophil dysfunction. [ABSTRACT FROM AUTHOR]

This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle. [ABSTRACT FROM AUTHOR]

Case history: Two commercial pasture-based farms within the North Canterbury district of New Zealand were feeding fodder beet (Beta vulgaris vulgaris L.) as a large proportion of the diet to cows during the dry period. On each farm 25 multiparous cows were blood sampled up to six times from 28 days before, to 21 days after calving (Day 0). Plasma samples were analysed for concentrations of β-hydroxybutyrate (BHBA), non-esterified fatty acid (NEFA), Ca, Mg and P, and aspartate aminotransferase (AST) activity. The first sampling visit was performed when cows were being fed their maximum intake of fodder beet. Clinical findings: The mean body condition score (BCS) of cows on Farm 1 was 5.4 (95% CI = 5.3–5.6) and on Farm 2, 5.4 (95% CI = 5.3–5.6) at first sampling. Mean concentrations of BHBA increased between Days −15 and Day −8 then decreased postpartum on Day 2 before increasing again on Day 21. On Farm 2, concentrations remained low (<1.2 mmol/L) on all days of sampling. Mean concentrations of NEFA in plasma remained low during the periparturient period on Farm 1, then increased on Day 2. On Farm 2, concentrations were elevated above 0.3 mmol/L between Days −28 and −17 then decreased on Day −10, before increasing on Day 2. Mean concentrations of Ca, Mg and P were higher than threshold values on both farms prepartum. However on Day 2, there were 8/23 (35%) cows on Farm 1 and 6/23 (26%) cows on Farm 2 with concentrations of Ca in plasma <2.0 mmol/L, and 10/23 (44%) cows on Farm 1 and 8/23 (35%) cows on Farm 2 with concentrations of P in plasma <1.3 mmol/L. Mean AST activities remained relatively constant and below 130 IU/L on both farms at all sampling times. Clinical relevance: On both farms, post-partum hypocalcaemia and hypophosphataemia were common after calving despite differing fodder beet feeding and mineral supplementation regimes. There was more variation in energy status, especially prior to calving. More research is required on factors affecting mineral and energy status in dry cows fed fodder beet. [ABSTRACT FROM AUTHOR]

Out of 154 crossbred cows, 80 cows (51.94 percent) exhibited peri-parturient disorders of which clinical and sub-clinical diseases were recorded in 40.00 and 18.75 percent, respectively while 41.25 percent of cows had both clinical and subclinical diseases. The frequently observed clinical conditions in transition cows were retention of placenta (10.39 percent), mastitis and dystocia (6.49 percent) and in sub-clinical conditions, hypocalcemia (30.51 percent) was predominant. The mean serum calcium values (mg/dL) significantly reduced in cows with clinical/sub-clinical diseases during transition period. The serum BHBA values in affected cows were increased ranging from 0.11 m mol/L to 7.60 m mol/L. [ABSTRACT FROM AUTHOR]

Our objectives were to assess the effects of a diet with a negative dietary cation-anion difference (DCAD) before calving on phagocytosis (Pc) and oxidative burst (OB) function of circulating neutrophils, and to determine the associations of serum ionized (iCa) and total calcium (tCa) concentrations with Pc and OB in transition dairy cows. We hypothesized that multiparous cows fed a negative DCAD diet prepartum would have greater iCa and tCa, and thus improved Pc and OB. From 3 wk before expected parturition until calving, 38 healthy multiparous cows from 3 farms were assigned to negative DCAD treatment (TRT; −100 mEq/kg of diet dry matter; n = 21) or a control (CON; 95 mEq/kg of dry matter; n = 17) diet. Each farm was on one treatment or the other at a time, but all farms contributed cows to both groups. Urine pH was measured weekly and in TRT was 6.1 ± 0.8 with 80% of 50 samples <7 and 74% ≤ 6.5. Phagocytosis, OB, iCa, and tCa were measured at d −7, 1, and 4 relative to calving. Median fluorescence intensity for Pc (MFIP) and OB (MFIOB), and the shift of percentage of cells active for Pc (PPc) and OB (POB) were measured in isolated, stimulated neutrophils via flow cytometry. Outcomes were assessed with mixed linear regression models accounting for repeated measures. There were no differences between treatments in the 4 neutrophil function outcomes. Although MFIOB varied over time, there were no interactions of treatment with time for any outcome. Serum ionized and tCa did not differ between TRT and CON. The least squares means ± standard deviation for iCa were: d −7, 1.23 ± 0.12 vs. 1.21 ± 0.12; d 1, 1.07 ± 0.12 vs. 1.02 ± 0.12; d 4, 1.16 ± 0.12 vs. 1.17 ± 0.12 mmol/L for TRT and CON, respectively; and for tCa: d −7 2.39 ± 0.25 vs 2.44 ± 0.31; d 1, 2.01 ± 0.25 vs 1.97 ± 0.31; d 4, 2.33 ± 0.25 vs 2.32 ± 0.31 mmol/L, respectively. The proportion of blood samples with tCa <2.15mmol/L at d −7, 1 and 4 was 5, 76, and 13%, respectively, with no differences between TRT and CON. Correlations of iCa or tCa with each of the 4 polymorphonuclear leukocyte (PMN) function outcomes were weak (r < |0.3|). We did not observe the hypothesized differences in aspects of innate immunity in clinically healthy multiparous cows fed a negative DCAD. We underline that cows that experienced clinical disease were excluded from this study, which is important for interpretation of the results. [ABSTRACT FROM AUTHOR]

Vitamin E is an essential nutrient for cows, but the effect of vitamin E supplementation is often controversially discussed in the published literature. The main goal of this meta-analysis was to evaluate the effects of vitamin E supplementation on its serum and colostrum enrichment, milk yield (MY), and somatic cell counts (SCC), as well as on various reproductive variables of transition cows, by considering a large set of variables that might influence the responses to vitamin E supplementation. After a broad search in journals and databases with keywords related to transition cows supplemented with vitamin E and appropriate filtering of the results, 36 papers including 53 trials were selected, and their data were extracted into a database. A meta-analysis was conducted on the extracted data. The analysis showed enrichment of serum vitamin E both at parturition (effect size: 2.423) and postpartum (effect size: 0.473), but no effects of vitamin E supplementation on IgG concentration in colostrum (effect size: −0.05) were found. There was a tendency for supplemented cows to produce more milk (effect size: 1.29) during the first month of lactation. Because of large heterogeneity, a meta-regression was performed but none of the presumed influencing factors was identified as a potential variable affecting MY. Milk SCC, as an indicator of udder health, was unaffected by vitamin E supplementation. Vitamin E supplementation tended to decrease the calving to first estrus period (CFP), whereby supplementing Se and taking parity into account in the analysis significantly lowered the CFP. Cows receiving additional vitamin E had, on average, 6.1% fewer cases of retained placenta, whereby Se supplementation and breed were key factors improving the effect of vitamin E to reduce retained placenta. In this regard, breeds other than Holstein responded better and these cows showed a lower incidence of retained placenta. The supplemented cows showed fewer days open (effect size: −0.31), and this improvement was affected linearly by increasing the dosage administered. Also, cows showed fewer services per conception with increasing dosage of vitamin E. In conclusion, this analysis showed that supplementing vitamin E did not affect SCC or colostrum quality but improved reproductive performance of transition cows, an effect consistent with increased levels of serum vitamin E and, for some variables, being modulated by Se supplementation. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to examine production performance responses to feeding rumen-protected choline (RPC) or methionine (RPM), or both, during the periparturient period. Fifty-four Holstein cows (25 primiparous, 29 multiparous) were used in a randomized block design experiment with a 2 × 2 factorial treatment structure. Cows were blocked by expected calving date and parity and assigned to 1 of 4 treatments: CON (no RPC or RPM); RPC (13.0 g/d of choline ion); RPM (9 g/d of dl -methionine prepartum; 13.5 g/d of dl -methionine postpartum); or RPC + RPM. Treatments were applied once daily as a top-dress from 3 wk before through 5 wk after calving. Dry matter intake and milk production were recorded daily, and milk samples were obtained once weekly. Data were analyzed for primi- and multiparous cows separately, using a repeated-measures mixed model that included random effects of cow and block and fixed effects of RPC, RPM, week, and their interactions; week served as the repeated effect. Initial BW and previous lactation milk yield were included as covariates in the statistical model for multiparous cows. Feeding RPC without RPM increased milk yield for multiparous cows by 8.7 kg/d, but this increase was not observed when RPC was fed with RPM. In multiparous cows, feeding RPM increased milk fat concentration and tended to increase milk fat yield. Because of this, RPM increased fat-corrected milk (FCM) by 2.8 kg/d at wk 2 postpartum, and this increase was sustained through wk 5 postpartum. In contrast, RPM did not affect overall milk fat yield and concentration for primiparous cows. Feeding RPC increased milk yield for primiparous cows by 3.5 kg/d irrespective of RPM inclusion, which is contrary to observations in multiparous cows, where RPC increased milk yield only in the absence of RPM. These results indicate that responses to RPC during the periparturient period may be dependent upon supply of methionine. Our observations also demonstrate that primi- and multiparous cows respond differently to RPC and RPM supplemented individually or simultaneously during the periparturient period. This variation in response could have been mediated by putative differences in choline and methionine requirements of primiparous versus multiparous cows, or by differences in the levels of milk production between the 2 groups (36 vs. 25 kg of FCM/d). However, cows in this study did not experience severe negative energy balance (mean nadirs of −6.6 and −5.0 Mcal/d for multiparous and primiparous cows, respectively), which likely affected their responses to RPC and RPM. [ABSTRACT FROM AUTHOR]

The objective of the current study was to characterize muscle and blood serum acylcarnitine (AcylCN) profiles and to determine the mRNA abundance of muscle carnitine acyltransferases in periparturient dairy cows with high (HBCS) and normal body condition (NBCS). Fifteen weeks antepartum, 38 pregnant multiparous Holstein cows were assigned to 2 groups that were fed differently to reach the targeted BCS and backfat thickness (BFT) until dry-off at −49 d before calving (HBCS: BCS >3.75 and BFT >1.4 cm; NBCS: <3.5 and <1.2 cm). Thereafter, both groups were fed identical diets. Blood samples and biopsies from the semitendinosus muscle were collected on d −49, 3, 21, and 84 relative to calving. Actual BCS at d −49 were 3.02 ± 0.24 and 3.82 ± 0.33 (mean ± SD) for NBCS and HBCS, respectively. In both groups, serum profiles showed marked changes during the periparturient period, with decreasing concentrations of free carnitine and increasing concentrations of long-chain AcylCN. Compared with NBCS, HBCS had greater serum long-chain AcylCN in early lactation, which may point to an insufficient adaptation of their metabolism in response to the metabolic load of fatty acids around parturition. The muscle concentrations of C5-, C9-, C18:1-, and C18:2-AcylCN were lower and those of C14:2-AcylCN were greater in HBCS than in NBCS cows. The mRNA abundance of carnitine palmitoyltransferase (CPT)1, muscle isoform (CPT1b) and CPT2 increased from d −49 to early lactation (d 3, d 21), followed by a decline to nearly antepartum values by d 84; this change was not affected by group. In conclusion, over-conditioning around calving seems to be associated with mitochondrial overload, which can result in incomplete fatty acid oxidation in dairy cows. [ABSTRACT FROM AUTHOR]

The transition from late gestation to early lactation is associated with extensive changes in metabolic, endocrine, and immune functions in dairy cows. Skeletal muscle plays an important role in maintaining the homeorhetic adaptation to the metabolic needs of lactation. The objective of this study was to characterize the skeletal muscle metabolome in the context of the metabolic changes that occur during the transition period in dairy cows with high (HBCS) versus normal body condition (NBCS). Fifteen weeks antepartum, 38 pregnant multiparous Holstein cows were assigned to 1 of 2 groups, which were fed differently to reach the targeted BCS and back fat thickness (BFT) until dry-off at −49 d before calving (HBCS: >3.75 and >1.4 cm; NBCS: <3.5 and <1.2 cm). During the dry period and the subsequent lactation, both groups were fed identical diets. The differences in both BCS and BFT were maintained throughout the study. The metabolome was characterized in skeletal muscle samples (semitendinosus muscle) collected on d −49, 3, 21, and 84 relative to calving using a targeted metabolomics approach (AbsoluteIDQ p180 kit; Biocrates Life Sciences AG, Innsbruck, Austria), which allowed for the quantification of up to 188 metabolites from 6 different compound classes (acylcarnitines, amino acids, biogenic amines, glycerophospholipids, sphingolipids, and hexoses). On d −49, the concentrations of citrulline and hydroxytetradecadienyl- l -carnitine in muscle were higher in HBCS cows than in NBCS cows, but those of carnosine were lower. Over-conditioning did not affect the muscle concentrations of any of the metabolites on d 3. On d 21, the concentrations of phenylethylamine and linoleylcarnitine in muscle were lower in HBCS cows than in NBCS cows, and the opposite was true for lysophosphatidylcholine acyl C20:4. On d 84, the significantly changed metabolites were mainly long-chain (>C32) acyl-alkyl phosphatidylcholine and di-acyl phosphatidylcholine, along with 3 long-chain (>C16) sphingomyelin that were all lower in HBCS cows than in NBCS cows. These data contribute to a better understanding of the metabolic adaptation in skeletal muscle of dairy cows during the transition period, although the physiological significance and underlying molecular mechanisms responsible for the regulation of citrulline, hydroxytetradecadienyl- l -carnitine, carnosine, and phenylethylamine associated with over-conditioning are still elusive and warrant further investigation. The changes observed in muscle lysophosphatidylcholine and phosphatidylcholine concentrations may point to an alteration in phosphatidylcholine metabolism, probably resulting in an increase in membrane stiffness, which may lead to abnormalities in insulin signaling in the muscle of over-conditioned cows. [ABSTRACT FROM AUTHOR]

Objectives were to evaluate the effect of prepartum energy intake and peripartal supplementation of ruminally protected choline (RPC) on select indicators of immune status in blood plasma and on lipopolysaccharide-stimulated blood cells ex vivo. At 47 ± 6 d before the expected calving date, 93 multiparous Holstein cows were assigned randomly to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement. Cows were fed energy to excess [EXE; 1.63 Mcal of net energy for lactation (NE L)/kg of dietary dry matter (DM)] or to maintenance (MNE; 1.40 Mcal of NE L /kg of dietary DM) ad libitum throughout the nonlactating period. The RPC was fed at 0 or 60 g/d to supply 0 or 12.9 g/d of choline ions top-dressed for 17 ± 4.6 d prepartum through 21 d postpartum. After calving, cows were fed the same methionine-supplemented diet, apart from RPC supplementation. During the last 2 wk before calving and during the first 5 wk postpartum, blood was sampled repeatedly and analyzed for cell types, acute-phase proteins, tumor necrosis factor-α (TNFα), and neutrophil function. Samples of whole blood were collected at 3 and 14 DIM and stimulated with 1 μg/mL lipopolysaccharide (LPS) in vitro for 6 and 24 h. After 6 h of LPS exposure, peripheral blood leucocytes (PBL) were harvested, and relative transcript abundance for select cytokines were measured. Supernatant was analyzed for TNFα after 24 h of LPS exposure. The PBL from cows fed EXE diets during the whole dry period had increased transcripts for the proinflammatory cytokines CXCL8 and TNF , although the plasma concentrations of the acute-phase proteins haptoglobin and fibrinogen, and the killing activity of the blood neutrophils in the postpartum period, were not affected by feeding different energy levels prepartum. Feeding RPC to cows overfed energy prepartum modulated their inflammatory state, as evidenced by decreased IL6 in PBL and reduced mean fluorescence intensity of CD14 during the postpartum period, compared with cows not fed RPC. Feeding RPC also decreased TNFα protein production, abundances of IL1B , CXCL8 , and TNF transcripts, and mean fluorescence intensity of CD80 of PBL stimulated by LPS, regardless of prepartum energy intake. In contrast, proportions of blood neutrophils undergoing phagocytosis and oxidative burst were increased at 17 d postpartum in cows supplemented with RPC. Collectively, these data indicate that transition cows supplemented with RPC experienced less inflammation, which may partially explain increased milk production in cows supplemented with RPC. [ABSTRACT FROM AUTHOR]

Vitamin D supports several physiological functions, from mineral homeostasis to immune activity. The aim of this study was to provide 25-hydroxyvitamin D3 [25(OH)D3] to late gestation and early lactation dairy cows and evaluate the impact on lactational performance. Holstein cows (n = 100) that finished their first or greater lactation were enrolled in a randomized block design with a 2x2 factorial arrangement of treatments (n = 25 cows per treatment group). Prepartum treatments were 0 or 3 mg of 25(OH)D3 per cow daily from 28 d before expected calving until calving. Postpartum treatments were 0 or 1.5 mg of 25(OH)D3 per cow daily from calving until 63 d after calving. Treatments were top-dressed at feed delivery using a cornmeal carrier. The 25(OH)D3 source was Hy· D100. Prepartum [30 IU/kg body weight (BW)] and lactation (40 IU/kg BW) rations also provided a basal amount of cholecalciferol fed to NASEM 2021 recommendations. Dry cows were fed individually, and group housed in a bedded pack. Lactating cows were fed individually, group housed in a freestall, milked 3x/d, and milk sampled 6x/wk. Data were analyzed by ANOVA with repeated measures using the MIXED procedure of SAS (v. 9.4). The model contained fixed effects [prepartum treatment (PRE), postpartum treatment (POST; removed for prepartum data) week, and their interactions] and a random effect (block). Prepartum dry matter intake (DMI) averaged 16.3 kg/d and 2.04% of BW, was not affected by prepartum treatment (P = 0.89) and was decreased closer to calving (P = 0.01). As expected, week after calving affected (P = 0.05) lactational performance. Postpartum DMI was greater for cows fed 3-1.5 mg than those fed 0 to 1.5 mg (Table 1). Colostrum yield and quality were not affected by prepartum treatment (P = 0.91) and averaged 5.7 kg with an IgG content of 75.6 g/L. Actual milk yield was not affected by prepartum or postpartum treatments. Interestingly, there was a carryover effect of prepartum treatment on yield of 4% fat-corrected milk (FCM) and energy-corrected milk (ECM). Cows fed 3 mg during late gestation produced more than those fed 0 mg. Postpartum treatment did not affect componentcorrected milk yield. Providing additional vitamin D in the form of 25(OH)D3 to late gestation cows improved lactational performance by increasing intake and the yield of component-corrected milk. [ABSTRACT FROM AUTHOR]

Lying behaviour and activity were measured in healthy grazing dairy cows during the transition from late gestation to early lactation (i.e. the transition period). Behaviour data derived from IceTag® or IceQube® (IceRobotics, Edinburgh, Scotland, UK) tri-axial accelerometers were collated from 311 cow parities of mixed age and breed (Holstein–Friesian, Jersey and crossbred Holstein–Friesian × Jersey) cows from four experiments. The IceTag and IceQube devices captured lying and step data at 1- and 15-min intervals respectively. Behaviour was recorded during the transition period (Day –21 prepartum to Day 34 postpartum) to determine daily lying time, number of lying bouts (LB), mean LB duration and number of steps. The effect of rainfall and air temperature on lying behaviour and activity during two periods, namely, prepartum (Day –21 to Day –3) and postpartum (Days 3–34) was evaluated. Multiple-regression analysis determined that decreased air temperature and increased rainfall is associated with a decline in daily lying time, number of LB and LB duration during both prepartum and postpartum periods. Exposure to both wet and cold conditions exacerbated the behavioural response. The results highlighted the importance of considering the effects of air temperature and rainfall and the interaction of these two climate variables when analysing lying behaviour and activity. Further work is required to quantify the trigger points for this activity modulation, to help understand the balance of welfare experiences in the life of a grazing cow. Lying time is a high-priority behaviour in dairy cows and electronic monitoring of lying behaviour is of interest in grazing systems. The aim of the present study was to determine the effect of inclement weather on the modification of lying behaviour in grazing dairy cows. There appears to be a direct thermal effect associated with behaviour in dairy cows exposed to brief periods of inclement weather. Researchers should consider climatic factors when interpreting changes in behaviour in grazing dairy cows. [ABSTRACT FROM AUTHOR]

The objectives were to use meta-analytic methods to determine the effects of amount of supplemental choline ion as rumen-protected choline (RPC) starting prepartum on production and health of dairy cows. The literature was systematically reviewed and 21 experiments, with up to 66 treatment means and 1,313 prepartum parous cows, were included. All experiments had a treatment with no supplemental choline (0 g/d; n = 30 treatment means), and the amount of choline ion supplemented to treated cows ranged from 5.6 to 25.2 g/d (n = 36 treatment means). Duration of pre- and postpartum feeding of RPC averaged (±standard deviation) 22.0 ± 6.0 and 57.5 ± 42.2 d, respectively. Data collected included the ingredient composition and chemical analyses of pre- and postpartum diets, amount of choline ion supplemented, number of cows per treatment, frequency of health events, and the least squares means and respective standard error of the means for production responses, liver composition, and blood parameters. The concentrations of net energy for lactation and metabolizable amino acids and protein (MP) in pre- and postpartum diets were predicted for each treatment mean using National Research Council (2001). Mixed model meta-analysis was conducted including the random effect of experiment and weighting by the inverse of the standard error of the means squared. Increasing supplementation of choline ion during transition linearly increased pre- (β = 0.0184 ± 0.00425) and postpartum dry matter intake (β = 0.0378 ± 0.00974), and yields of milk (β = 0.436 ± 0.112), energy-corrected milk (ECM; β = 0.422 ± 0.0992), fat (β = 0.00555 ± 0.000793), and protein (β = 0.0138 ± 0.00378). Nevertheless, an interaction between choline and postpartum metabolizable methionine as a percent of MP (METMPPo) was observed for yields of milk, ECM, and protein because as METMPPo increased, the positive response to choline on yields of milk, ECM, and protein decreased. Supplementing choline during transition tended to reduce the risks of retained placenta and mastitis, but it had no effect on metritis, milk fever, displaced abomasum and ketosis, or the concentration of triacylglycerol in the hepatic tissue postpartum. The median amount of choline ion supplemented was 12.9 g/d and responses in postpartum dry matter intake and yields of milk, ECM, fat, and protein to that amount of supplementation were 0.5, 1.6, 1.7, 0.07, and 0.05 kg/d, respectively. No interactions were observed between supplemental choline and prepartum dietary net energy for lactation or metabolizable methionine as a percent of MP. Collectively, feeding RPC during the transition period improves performance in parous cows. Increases in yields of milk and milk components were observed in spite of pre- and postpartum diets, although the increments in milk, ECM, and protein yields with supplementing choline decreased as the concentration of methionine in postpartum diets increased. The optimum dose of choline ion was not detected, but likely it is more than the 12.9 g/d fed in most experiments evaluated in the current meta-analysis. Finally, the meta-analysis identified lack of sufficient data to understand the role of supplemental choline in nulliparous cows. [ABSTRACT FROM AUTHOR]

The objective of the current study was to investigate the effects of overconditioning around calving on gene expression of key components of the mammalian target of rapamycin (mTOR) pathway and ubiquitin-proteasome system (UPS) in skeletal muscle as well as the AA profiles in both serum and muscle of periparturient cows. Fifteen weeks antepartum, 38 multiparous Holstein cows were allocated to either a high body condition group (HBCS; n = 19) or a normal body condition group (NBCS; n = 19) and were fed different diets until dry-off (d −49 relative to calving) to amplify the difference. The groups were also stratified for comparable milk yields (NBCS: 10,361 ± 302 kg; HBCS: 10,315 ± 437 kg). At dry-off, the NBCS cows (parity: 2.42 ± 1.84; body weight: 665 ± 64 kg) had a body condition score (BCS) <3.5 and backfat thickness (BFT) <1.2 cm, whereas the HBCS cows (parity: 3.37 ± 1.67; body weight: 720 ± 57 kg) had a BCS >3.75 and BFT >1.4 cm. During the dry period and the subsequent lactation, both groups were fed identical diets but maintained the BCS and BFT differences. Blood samples and skeletal muscle biopsies (semitendinosus) were repeatedly (d −49, +3, +21, and +84 relative to calving) collected for assessing the concentrations of free AA and the mRNA abundance of various components of mTOR and UPS. The differences in BCS and BFT were maintained throughout the study. The circulating concentrations of most AA with the exception of Gly, Gln, Met, and Phe increased in early lactation in both groups. The serum concentrations of Ala (d +21 and +84) and Orn (d +84) were lower in HBCS cows than in NBCS cows, but those of Gly, His, Leu, Val, Lys, Met, and Orn on d −49 and Ile on d +21 were greater in HBCS cows than in NBCS cows. The serum concentrations of 3-methylhistidine, creatinine, and 3-methylhistidine:creatinine ratio increased after calving (d +3) but did not differ between the groups. The muscle concentrations of all AA (except for Cys) remained unchanged over time and did not differ between groups. The muscle concentrations of Cys were greater on d −49 but tended to be lower on d +21 in HBCS cows than in NBCS cows. On d +21, mTOR and eukaryotic translation initiation factor 4E binding protein 1 mRNA abundance was greater in HBCS cows than in NBCS cows, whereas ribosomal protein S6 kinase 1 was not different between the groups. The mRNA abundance of ubiquitin-activating enzyme 1 (d +21), ubiquitin-conjugating enzyme 1 (d +21), atrogin-1 (d +21), and ring finger protein-1 (d +3) enzymes was greater in HBCS cows than in NBCS cows, whereas ubiquitin-conjugating enzyme 2 was not different between the groups. The increased mRNA abundance of key components of mTOR signaling and of muscle-specific ligases of HBCS cows may indicate a simultaneous activation of anabolic and catabolic processes and thus increased muscle protein turnover, likely as a part of the adaptive response to prevent excessive loss of skeletal muscle mass during early lactation. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the differences in the metabolic profiles in serum of dairy cows that were normal or overconditioned when dried off for elucidating the pathophysiological reasons for the increased health disturbances commonly associated with overconditioning. Fifteen weeks antepartum, 38 multiparous Holstein cows were allocated to either a high body condition (HBCS; n = 19) group or a normal body condition (NBCS; n = 19) group and were fed different diets until dry-off to amplify the difference. The groups were also stratified for comparable milk yields (NBCS: 10,361 ± 302 kg; HBCS: 10,315 ± 437 kg; mean ± standard deviation). At dry-off, the cows in the NBCS group (parity: 2.42 ± 1.84; body weight: 665 ± 64 kg) had a body condition score (BCS) <3.5 and backfat thickness (BFT) <1.2 cm, whereas the HBCS cows (parity: 3.37 ± 1.67; body weight: 720 ± 57 kg) had BCS >3.75 and BFT >1.4 cm. During the dry period and the subsequent lactation, both groups were fed identical diets but maintained the BCS and BFT differences. A targeted metabolomics (AbsoluteIDQ p180 kit, Biocrates Life Sciences AG, Innsbruck, Austria) approach was performed in serum samples collected on d −49, +3, +21, and +84 relative to calving for identifying and quantifying up to 188 metabolites from 6 different compound classes (acylcarnitines, AA, biogenic amines, glycerophospholipids, sphingolipids, and hexoses). The concentrations of 170 metabolites were above the limit of detection and could thus be used in this study. We used various machine learning (ML) algorithms (e.g., sequential minimal optimization, random forest, alternating decision tree, and naïve Bayes–updatable) to analyze the metabolome data sets. The performance of each algorithm was evaluated by a leave-one-out cross-validation method. The accuracy of classification by the ML algorithms was lowest on d 3 compared with the other time points. Various ML methods (partial least squares discriminant analysis, random forest, information gain ranking) were then performed to identify those metabolites that were contributing most significantly to discriminating the groups. On d 21 after parturition, 12 metabolites (acetylcarnitine, hexadecanoyl-carnitine, hydroxyhexadecenoyl-carnitine, octadecanoyl-carnitine, octadecenoyl-carnitine, hydroxybutyryl-carnitine, glycine, leucine, phosphatidylcholine-diacyl-C40:3, trans -4-hydroxyproline, carnosine, and creatinine) were identified in this way. Pathway enrichment analysis showed that branched-chain AA degradation (before calving) and mitochondrial β-oxidation of long-chain fatty acids along with fatty acid metabolism, purine metabolism, and alanine metabolism (after calving) were significantly enriched in HBCS compared with NBCS cows. Our results deepen the insights into the phenotype related to overconditioning from the preceding lactation and the pathophysiological sequelae such as increased lipolysis and ketogenesis and decreased feed intake. [ABSTRACT FROM AUTHOR]

MicroRNA (miRNA) are abundant in milk, and likely have regulatory activity involving lactation and immunity. The objective of this study was to determine the miRNA profile in colostrum of overconditioned cows compared with cows of more moderate body condition score (BCS) at calving. Multiparous cows with either high (≥4.0 on a scale of 1 to 5; n = 7) or moderate BCS (2.75 to 3.50; n = 9) in the week before parturition were selected from a commercial dairy herd. Blood and colostrum were sampled within 24 h after calving. Blood serum was analyzed for free fatty acid (FFA) concentration. MicroRNA was isolated from colostrum samples after removing milk fat and cells. MicroRNA were sequenced, and reads were mapped to the bovine genome and to the existing database of miRNA at miRBase.org. Two programs, Oasis 2.0 and miRDeep2, were employed in parallel for read alignment, and analysis of miRNA count data was performed using DESeq2. Identification of differentially expressed miRNA from DESeq2 was not affected by the differences in miRNA detected by the 2 mapping programs. Most abundant miRNA included miR-30a, miR-148a, miR-181a, let-7f, miR-26a, miR-21, miR-22, and miR-92a. Large-scale shifts in miRNA profile were not observed; however, colostrum of cows with high BCS contained less miR-486, which has been linked with altered glucose metabolism. Colostrum from cows with elevated serum FFA contained less miR-885, which may be connected to hepatic function during the transition period. Potential functions of abundant miRNA suggest involvement in development and maintenance of cellular function in the mammary gland, with the additional possibility of influencing neonatal tissue and immune system development. [ABSTRACT FROM AUTHOR]

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP. [ABSTRACT FROM AUTHOR]

• Predicting calving time based on a novel monitoring system for ingestive behavior. • Evaluating performance with independent training and validation datasets of calving. • Variables of rumination behavior had most value to predict the start of calving. • Low positive predictive values despite satisfying sensitivity and specificity. • Positive predictive values increased for 24-h versus 168-h timeframe ante partum. Calving is an event with major impact on working routines in dairy farming and highly affects the physiological state of dairy cows. Hence, it is in the interest of livestock farmers to have information on approaching calving events to ensure a sound birth, health and welfare of the dairy cow and calf for profitable and sustainable milk production. Changes in the ingestive behavior of dairy cows due to the onset of calving have been revealed in several studies. Therefore, sensor data of these behaviors may be useful for automated prediction of calving time. The current study used sensor data of a novel monitoring device for ingestive behavior (RumiWatch noseband sensor, Agroscope, Ettenhausen, Switzerland and Itin+Hoch GmbH, Liestal, Switzerland) of 35 dairy cows for development and validation of a predictive model for calving time. Sensor data obtained from calving events on three farms were used as one training dataset and two independent validation datasets to evaluate the predictive performance of a Naïve Bayes classifier model for calving prediction at 1 h before the start of calving. The model performance was evaluated on an hourly basis for 168 h prior to the start of calving. Combined sensor variables with highest predictive performance were ruminating chews, ruminating boluses, and eating chews (sensitivity = 0.82, specificity = 0.87, positive predictive value = 0.04) in Validation Dataset 1, and ruminating chews per bolus, ruminating chews per minute, eating chews, other activity time, other chews (sensitivity = 0.69, specificity = 0.86, positive predictive value = 0.03) in Validation Dataset 2. These results indicate, that the sensitivity and specificity of the predictive model were satisfying, but the positive predictive value was low and the amount of false positive alerts was considerably high. Although the developed model is therefore not suitable for application in practice, we found that particularly variables of rumination behavior have predictive value and should be taken into consideration for future research on calving detection models. The findings of this study demonstrate that an assessment limited to the terms of sensitivity and specificity may be misleading, as these variables may achieve high values and suggest adequate performance, while the model is not appropriate in the light of its expected use. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of feeding synthetic zeolite A for 3 wk before expected calving on peripartal serum mineral concentrations, hypocalcemia, oxidant status, and performance. Holstein cows (n = 55) entering their second or greater lactations were assigned randomly to 1 of 2 dietary treatments starting 21 d before expected calving: control (CON: 40% corn silage, 33% wheat straw, and 27% concentrate; n = 29) or experimental [EXP: CON plus zeolite A (X-Zelit, Protekta Inc., Lucknow, ON, Canada/Vilofoss, Graasten, Denmark; n = 26) at an inclusion rate of 3.3% of dry matter, targeting 500 g/d as-fed]. Cows were fed the same postpartum diet and housed in individual tiestalls through 28 d in milk. Cows fed EXP had higher serum Ca concentrations as parturition approached and during the immediate postpartum period. Serum P concentrations were lower for the EXP-fed cows during the prepartum period and the first 2 d of lactation, whereas serum Mg concentrations were lower than those of the CON-fed cows only during the immediate periparturient period. Cows fed EXP had decreased prevalence of subclinical hypocalcemia (SCH) from d −1 through 3 relative to day of parturition, with the largest difference occurring within the first day postpartum. Prepartum dry matter intake tended to be decreased and rumination was decreased in cows fed EXP; however; postpartum dry matter intake, rumination, milk yield, milk component yield, and colostrum measurements did not differ between treatments. Cows fed EXP tended to have increased hazard of pregnancy by 150 d in milk when controlling for parity compared with CON-fed cows; potential reproductive benefits merit further study. This study demonstrated that zeolite A supplementation during the prepartum period results in markedly improved serum Ca concentrations around parturition and similar postpartum performance compared with controls and is effective at decreasing hypocalcemia in multiparous Holstein cows. [ABSTRACT FROM AUTHOR]

• This study evaluated the effect of rumen-protected glucose (RPG) on milk production and metabolism of transition dairy cows. • Supplementation with RPG improved milk production without affecting milk composition. • Supplementation with RPG reduced inflammatory markers in transition cows. Supplementation of rumen-protected glucose (RPG) may be a useful dietary strategy to improve energy balance in transition dairy cows. The present study was performed to investigate whether supplementation with RPG could improve milk production and reduce inflammation or infection during the transition period in cows. Twelve Holstein cows (age, 4–5 yrs; bodyweight, 515 ± 42 kg; milk yield, 16.1 ± 3.7 kg/d)in late gestation were allotted to one of 2 treatments. The treatments were a basal diet plus 200 g/d of RPG (450 g/kg of glucose, 450 g/kg of coating fat and 100 g/kg of water) or a basal diet plus 90 g/d of coating fat (CON). Treatments were applied from 1 wk before to 2 wk after calving. Animal performance data were recorded, and the overall tract apparent digestibility of prepartum or postpartum cows was determined. Blood was sampled on d −4, 0, 7, and 14 to examine the plasma biochemical parameters and proinflammatory cytokines. The RPG supplementation increased the milk yield, but did not change the dry matter intake. Compared with cows in the CON group, the plasma total protein concentration was lower in the RPG group. Cows in the RPG group had greater plasma albumin concentrations but lower globulin and interleukin-8 concentrations during the transition period. The RPG supplementation tended to increase the plasma alanine aminotransferase concentration but did not change the plasma aspartate aminotransferase concentration. Dietary RPG supplementation increased the non-esterified fatty acid concentration and tended to decrease the plasma glucose concentration. In conclusion, these results indicate that supplementation with 200 g RPG per day improves milk production and reduces inflammatory markers but might have compromised the liver function of the transition cows in this study. [ABSTRACT FROM AUTHOR]

Objective: An experiment was conducted to determine the effect of reduced energy density of close-up diets on metabolites, lipolysis and gluconeogenesis in cows during the transition period. Methods: Thirty-nine Holstein dry cows were blocked and assigned randomly to three groups, fed a high energy density diet (HD, 1.62 Mcal of net energy for lactation [NEL]/kg dry matter [DM]), a medium energy density diet (MD, 1.47 Mcal NEL/kg DM), or a low energy density diet (LD, 1.30 Mcal NEL/kg DM) prepartum,they were fed the same lactation diet to 28 days in milk (DIM). All the cows were housed in a free-stall barn and fed ad libitum. Results: The reduced energy density diets decreased the blood insulin concentration and increased nonesterified fatty acids (NEFA) concentration in the prepartum period (p<0.05). They also increased the concentrations of glucose, insulin and glucagon, and decreased the concentrations of NEFA and β-hydroxybutyrate during the first 2 weeks of lactation (p<0.05). The plasma urea nitrogen concentration of both prepartum and postpartum was not affected by dietary energy density (p>0.05). The dietary energy density had no effect on mRNA abundance of insulin receptors, leptin and peroxisome proliferator-activated receptor-γ in adipose tissue, and phosphoenolpyruvate carboxykinase, carnitine palmitoyltransferase-1 and peroxisome proliferator-activated receptor-α in liver during the transition period (p>0.05). The HD cows had higher mRNA abundance of hormone-sensitive lipase at 3 DIM compared with the MD cows and LD cows (p = 0.001). The mRNA abundance of hepatic pyruvate carboxykinase at 3 DIM tended to be increased by the reduced energy density of the close-up diets (p = 0.08). Conclusion: The reduced energy density diet prepartum was effective in controlling adipose tissue mobilization and improving the capacity of hepatic gluconeogenesis postpartum. [ABSTRACT FROM AUTHOR]

Postpartum dietary supplementation of gluconeogenic precursors may improve the plasma metabolite profile of dairy cows, reducing metabolic disorders and improving lactation performance. The objective of this trial was to examine the effects of supplementation with fermented ammoniated condensed whey (FACW) postpartum on lactation performance and on profile of plasma metabolites and hormones in transition dairy cows. Individually fed multiparous Holstein cows were blocked by calving date and randomly assigned to control (2.9% dry matter of diet as soybean meal; n = 20) or FACW (2.9% dry matter of diet as liquid Gluco- Boost, Fermented Nutrition, Luxemburg, WI; n = 19) dietary treatments. Treatments were offered from 1 to 45 d in milk (DIM). Cows were milked twice a day. Dry matter intake and milk yield were recorded daily and averaged weekly. Individual milk samples from 2 consecutive milkings were obtained once a week for component analysis. Rumen fluid was collected (n = 3 cows/ treatment) at 4 time points per day at 7 and 21 DIM. Blood samples were collected within 1 h before feeding time for metabolite analysis and hyperketonemia diagnosis. Supplementation of FACW improved feed efficiency relative to control; this effect may be partially explained by a marginally significant reduction in dry matter intake from wk 3 to 7 for FACW-supplemented cows with no detected FACW-driven changes in milk yield, milk protein yield, and milk energy output compared with control. Also, there was no evidence for differences in intake of net energy for lactation, efficiency of energy use, energy balance, or body weight or body condition score change from calving to 45 DIM between treatments. Supplementation of FACW shifted rumen measures toward greater molar proportions of propionate and butyrate, and lesser molar proportions of acetate and valerate. Cows supplemented with FACW had greater plasma glucose concentrations in the period from 3 to 7 DIM and greater plasma insulin concentrations compared with control. Plasma nonesterified fatty acid and β-hydroxybutyrate concentrations were decreased in cows supplemented with FACW compared with control cows in the period from 3 to 7 DIM. These findings indicate that FACW may have improved the plasma metabolite profile immediately postpartum in dairy cows. Additionally, supplementation of FACW resulted in improved feed efficiency as accessed by measures of milk output relative to feed intake. [ABSTRACT FROM AUTHOR]

The objectives were to use meta-analytic methods to determine the effects of changes in dietary cation-anion difference (DCAD) prepartum on productive performance and health of dairy cows. The literature was systematically reviewed, searching randomized experiments with transition cows that manipulated the prepartum DCAD or experiments with acidogenic diets in which dietary Ca, P, or Mg was manipulated. Forty-two experiments, including 134 treatment means and 1,803 cows, were included in the meta-analysis. Of those, 5 experiments with 15 treatment means reported responses for 151 nulliparous cows. Data collected included the mineral composition of prepartum diets, parity group prepartum, breed, days on treatment, and means and respective measure of variance for urine pH, dry matter intake (DMI), body weight, body condition, productive performance, concentrations of minerals and metabolites in blood, and incidence of diseases. Mixed effects meta-analyses were conducted weighting by the inverse of standard error of the means squared to account for the precision of each experiment. Models include the effects of DCAD, parity group prepartum, interaction between DCAD and parity group, and other covariates that showed significance in univariable analysis. Final models were selected based on parsimony and model fit. Reducing the prepartum DCAD reduced intake prepartum but improved intake postpartum in both parity groups. Interactions between DCAD and parity group occurred for yields of milk, fat-corrected milk (FCM), fat, and protein because reducing the DCAD improved those responses in parous cows; however, reducing the DCAD either had no effect on yields of milk and protein or reduced the yield of FCM and fat in nulliparous cows. The resulting equations from the statisticalmodels predicted that reducing the DCAD from +200 to -100 mEq/kg would increase blood total Ca on the day of calving from 1.86 to 2.04 ± 0.05 mM, DMI postpartum 1.0 kg/d, and milk yield 1.7 kg/d in parous cows. The increased concentrations of blood total Ca at calving and postpartum explained the marked reduction in risk of milk fever in parous cows with a reduction in DCAD. As the DCAD decreased, the risk of retained placenta and metritis also decreased, resulting in fewer disease events per cow in both nulliparous and parous cows. Dietary concentrations of Ca, P, or Mg prepartum had no effect on DMI or yields of milk and FCM; however, increasing dietary Ca within the study range of 0.16 to 1.98% of dry matter tended to increase the risk of milk fever in parous cows regardless of DCAD fed. Collectively, results support the recommendation of prepartum acidogenic diets to result in a negative DCAD to parous cows with improvements in lactation performance and reduced risk of diseases; however, the range of DCAD fed did not allow for detection of an optimum value for postpartum performance. On the other hand, despite improvements in blood concentrations of Ca and reduction in uterine diseases with a reduction in DCAD fed to nulliparous cows, productive performance was either depressed or unaffected and the limited number of experiments did not provide sufficient evidence for a recommended DCAD for this group of cows. [ABSTRACT FROM AUTHOR]

During the peripartum period, dairy cows often have signs of inflammation. Various stresses, including infectious and metabolic diseases, have been discussed as causative for this inflammation. In this study, expression profiles for 17 immune markers were measured in whole blood preparations from 78 dairy cows over a time frame starting 1 wk before calving to 4 wk after calving. Additionally, the effects of far-off and close-up feeding on immune function of dairy cows during the peripartum period were investigated. Cows were assigned to 1 of 2 feeding levels in late lactation to achieve a low and high BCS at the time of dry-off (approximately 4.25 and 5.0 on a 10-point scale). Following dry-off, both herds were managed to achieve a BCS of 5.0 one month before calving; this involved controlled feeding (i.e. maintenance) and over-feeding of ME during the far-off dry period. Within each far-off feeding-level treatment, cows were offered 65, 90, or 120% of their precalving ME requirements for 3 wk precalving in a 2 × 3 factorial arrangement. Analysis of gene expression profiles from blood cells revealed effects of time indicating that the transition cow's immune system counteracts the peripartum inflammation, whereas later postcalving it becomes activated to provide protection against postpartum infections. Far-off feeding affected (P < 0.05) the expression of 2 of the investigated genes at calving. Interleukin-6 (IL-6) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in unstimulated, peripheral leukocytes were lower (P < 0.05) in animals from the Far-Off_Over-fed group compared with the Far-Off_Control-fed group. Close-up feeding had several effects on gene expression, indicating that immune function in Feed120 animals was distinct from the Feed90 and Feed65. In conclusion, feeding management precalving becomes an important intervention to ensure immunocompetence at and after calving. [ABSTRACT FROM AUTHOR]

High-producing dairy cows with high pre-calving body condition score (BCS) are more susceptible to metabolic disorders and oxidative stress. The aim of present study was to evaluate the effects of close-up BCS and 3 times Se-vitamin E (SeE) injection on BCS change, blood metabolites, oxidative status, and milk yield in high-producing Holstein cows. A total of 136 multiparous cows were divided into 2 groups based on their BCS including high (HB = 4.00 ± 0.20) and moderate (MB = 3.25 ± 0.25) at 3 wk before expected calving time. Then, each group was divided into 2 subgroups: 3 rounds of SeE injection at 21 d before, and 0 and 21 d after calving (+SeE), and no SeE injection (-SeE). Four final experimental groups were HB+SeE, MB+SeE, HB-SeE, and MB-SeE (34 cows each). Results indicated that interaction effect of BCS and SeE affected serum glucose, and the MB+SeE group had the highest level. The HB cows lost more BCS compared with MB cows during the postcalving period. Moreover, serum insulin concentration increased after SeE injection. The HB cows had higher serum nonesterified fatty acids at 14 d after calving. The MB cows tended to have higher activity of blood glutathione peroxidase over the study period. Furthermore, the SeE-injected cows tended to have higher activity of blood glutathione peroxidase at 28 d after calving. Serum albumin level was increased by SeE injection. The HB cows had greater milk production than MB cows, and SeE-injected cows tended to have higher milk fat percentage and higher fat: protein ratio compared with nonsupplemented cows. It was concluded that SeE injection had beneficial effects on some blood metabolites, albumin as a blood antioxidative parameter, and lactation performance in high-producing dairy cows, especially cows with moderate close-up BCS. [ABSTRACT FROM AUTHOR]

The determinants of metabolic and reproductive health disorders in the peripartum period and the degree to which feeding and lying space and management can influence health are only partially understood. The objective of this randomized controlled study was to determine whether providing noncompetitive feeding and lying access in the close-up dry period improves health and immune function. Forty-eight Holstein cows of all parities were randomly assigned to a treatment group of 6 to 10 cows in 1 pen with either 80% cows to stalls and 90 cm of feeding space per cow (understocked) or 120% stocking density and 45 cm of feeding space per cow (overstocked) for 3 wk before expected calving. All cows wore electronic data loggers to monitor daily standing and lying time. Video recordings representing d 7 to 9 after group formation were reviewed, and a competition index (C_Ind) was calculated for each cow by dividing the number of times a cow displaced another as an actor by its total number of actor and reactor displacements. Cows were categorized as high success (C_Ind ≥0.6), moderate success (0.4 ≤ C_Ind <0.6), or low success (C_Ind <0.4). Weekly blood samples measured nonesterified fatty acids, β-hydroxybutyrate, calcium, glucose, albumin, aspartate aminotransferase, bilirubin, haptoglobin, insulin, and insulin-like growth factor-1 from 3 wk before to 5 wk after calving. Measures of innate immune function (neutrophil phagocytosis and oxidative burst) were assessed at −2, −1, 1, 2, 3, and 5 wk relative to calving. Liver biopsies were collected at wk 1 and 3. Cows in the understocked group spent significantly more time per day lying; the back-transformed least squares means and 95% confidence interval were 14.8 h (13.9–15.6) versus 12.8 h (12.0–13.7). Controlling for parity, there was no difference between treatments in β-hydroxybutyrate, nonesterified fatty acids, glucose, insulin, insulin-like growth factor 1, aspartate aminotransferase, bilirubin, or haptoglobin concentrations. Throughout the study, cows in the understocked treatment had higher mean calcium and tended to have higher albumin and at 3 wk after calving tended to have lower mean liver triacylglycerol content. Overall, there was no treatment effect on phagocytosis, but cows with a higher C_Ind in the understocked treatment group had greater oxidative burst function. There was no effect of treatment on endometritis. Despite increased competition and lower lying time, the expected harmful effects of crowding and competition on metabolic indicators and innate immune function were mostly not observed. Although this does not refute the importance of access to feeding and lying space, these results indicate that metabolic and reproductive health is more complex than can be explained solely by exposure to what are understood to be best practices for space allowances. [ABSTRACT FROM AUTHOR]

Our objectives were to determine (1) the effect of a single dose of an oral Ca bolus within 24 h after parturition on plasma Ca concentration, (2) the response of primiparous (PP) and multiparous (MP) cows to this supplementation strategy, and (3) differential responses based on plasma Ca at enrollment. For objective 1, cows from 1 commercial dairy in New York State were enrolled within 19 h after parturition (mean ± standard deviation = 8.3 ± 5.3 h) and randomized within parity group (first, second, and ≥third) to control [CON (n = 25); no placebo] or a single dose bolus treatment [BOL (n = 25); 3 oral Ca boluses supplying 54 to 64 g of Ca]. Plasma Ca was measured repeatedly between 1 and 24 h following treatment. For objectives 2 and 3, cows on 6 commercial farms in New York State were assigned to treatment as for objective 1 (CON, n = 1,973; BOL, n = 1,976). Herd records for health, reproduction, and Dairy Herd Improvement Association test day milk production were collected. Mixed effect multivariable models were developed using repeated measures ANOVA, Poisson regression, or proportional hazard models. Objective 2 analyses considered treatment with periparturient risk factors, whereas objective 3 analyses also considered Ca status. No difference was observed for plasma Ca between 1 and 24 h after treatment. Primiparous cows assigned to BOL calving at >712 d old had decreased risk of one or more health disorders [≤30 d in milk; risk ratio (RR) = 0.65, 95% confidence interval (CI) = 0.51 to 0.84] and those with body condition score >3.5 responded to BOL with increased milk production (CON = 31.7 ± 1.1, BOL = 35.1 ± 1.1 kg/d), as did those with days carried calf >277 (CON = 31.9 ± 1.0, BOL = 34.7 ± 1.0 kg/d). Reduced risk of one or more health disorders was observed in parity ≥3 (RR = 0.85, 95% CI = 0.81 to 0.89) and MP cows with body condition score >3.5 (retained placenta; RR = 0.70, 95% CI = 0.58 to 0.84) or that were lame (displaced abomasum; RR = 0.49, 95% CI = 0.32 to 0.75). Differential responses for PP cows by Ca status were minimal. For MP cows with low plasma Ca, BOL decreased risk of additional Ca treatment (≤1.8 mmol/L; RR = 0.57, 95% CI = 0.40 to 0.80) as well as risk of one or more health disorders (≤2.15 mmol/L; RR = 0.90, 95% CI = 0.85 to 0.95). Supplementation with a single oral dose of Ca could be targeted to periparturient risk groups for improved health. Calcium status did not differentiate responses of PP cows, but MP cows with low Ca at parturition had improved health status when supplemented. [ABSTRACT FROM AUTHOR]

The liver functionality index (LFI) represents an assessment of transition cow metabolic health by measuring changes in biomarkers associated with liver plasma protein synthesis (albumin), lipoprotein synthesis (cholesterol), and heme catabolism (bilirubin). The present analysis was conducted to determine the role of peripartal rumen-protected Met or choline (CHOL) supplementation on LFI groupings, and to assess relationships with performance, inflammation, oxidative stress status, and plasma AA profiles. A cohort of 40 multiparous Holstein cows that were part of a randomized complete block design with 2 × 2 factorial arrangement of Met (Smartamine M, Adisseo NA, Alpharetta, GA) and CHOL (ReaShure, Balchem Inc., New Hampton, NY) level (with or without) were used. From -21 d to calving, cows received the same close-up diet and were assigned randomly to each treatment. From calving to 30 d, cows were on the same postpartal diet and continued to receive the same treatments until 30 d. Addition of Met was adjusted daily at 0.08% dry matter of diet and CHOL was fed at 60 g/cow per day. Liver (-10, 7, 20, and 30 d) and blood (-10, 4, 8, 20, and 30 d) samples were harvested for biomarker analyses. Cows were ranked retrospectively and assigned to low (LLFI, LFI <0) and high (HLFI, LFI >0) LFI groups regardless of Met or CHOL supplementation. Compared with cows in LLFI, close-up and lactation DMI, milk yield, milk fat yield, and milk protein yield were greater in HLFI cows. As expected, cows in LLFI had lower plasma cholesterol and albumin but greater bilirubin concentrations around parturition. Plasma haptoglobin concentration was also lower in HLFI cows, but plasma paraoxonase and hepatic total and reduced hepatic glutathione concentrations were greater. Although higher concentrations of His, Met, and Trp, as well as a tendency for greater Ile, were observed in HLFI cows, overall essential AA concentrations did not differ with LFI status. In contrast, overall concentrations of nonessential AA were greater in HLFI cows due to greater circulating concentrations of Ala, Asn, Gln, Pro, and Ser. Similarly, overall concentrations of total AA and total sulfur-containing compounds were greater in cows with HLFI. Feeding Met compared with CHOL led to a tendency for more cows classified as HLFI. Overall, results support the broader application of the LFI in the management of transition cows. In that context, the fact that precalving concentrations of compounds such as reduced glutathione, total sulfurcontaining compounds, Met, Tau, and homocysteine differed between HLFI and LLFI independent of Met or CHOL feeding also underscores their potential for monitoring cows that might be at a greater risk of developing health problems after calving. Further studies on the applicability of these biomarkers to monitor transition success appears warranted. [ABSTRACT FROM AUTHOR]

The greatest risk of metabolic and infectious disease in dairy cows is during the transition from pregnancy to lactating (i.e., the transition period). The objective of this experiment was to determine the effects of extracellular vesicles (microvesicles involved in cell-to-cell signaling) isolated from transition cows on target cell function. We previously identified differences in the protein profiles of exosomes isolated from cows divergent in metabolic health status. Therefore, we hypothesized that these exosomes would affect target tissues differently. To investigate this, 2 groups of cows (n = 5/group) were selected based on the concentration of β-hydroxybutyrate and fatty acids in plasma and triacylglycerol concentration in liver at wk 1 and 2 postcalving. Cows with high concentrations of β-hydroxybutyrate, fatty acids, and triacylglycerol were considered at increased risk of clinical disease during the transition period (high-risk group; n = 5) and were compared with cows that had low concentrations of the selected health indicators (low-risk group; n = 5). At 2 time points during the transition period (postcalving at wk 1 and 4), blood was sampled and plasma exosomes were isolated from the high-risk and low-risk cows. The exosomes were applied at concentrations of 10 and 1 µg/mL to 5 x 10³ Madin-Darby bovine kidney cells grown to 50% confluence in 96-well plates. Results indicate a numerical increase in cell proliferation when exosomes from high-risk cows were applied compared with those from low-risk cows. Consistent with an effect on cell proliferation, quantitative reverse transcriptase PCR indicated a trend for upregulation of 3 proinflammatory genes (granulocyte colony-stimulating factor, ciliary neurotrophic factor, and CD27 ligand) with the application of high-risk exosomes, which are involved in cellular growth and survival. Proteomic analysis indicated 2 proteins in the low-risk group that were not identified in the high-risk group (endoplasmin and catalase), which may also be indicative of the metabolic state of origin. It is likely that the metabolic state of the transition cow affects cellular function through exosomal messaging; however, more in-depth research into cross-talk between exosomes and target cells is required to determine whether exosomes influence Madin-Darby bovine kidney cells in this manner. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the effect of decreasing dietary cation-anion difference [DCAD; (Na+ + K+) - (Cl- + S2-)] of the prepartum diet on aspects of mineral metabolism, energy metabolism, and performance of peripartum dairy cows. Multiparous Holstein cows (n = 89) were enrolled between 38 and 31 d before expected parturition and randomized to treatments in a completely randomized design (restricted to balance for previous 305-d mature equivalent milk production, parity, and body condition score) at 24 d before expected parturition. Treatments consisted of a low-K ration without anion supplementation [CON; n = 30, DCAD = +18.3 mEq/100 g of dry matter (DM)]; partial anion supplementation to a low-K ration (MED; n = 30, DCAD = +5.9 mEq/100 g of DM); and anion supplementation to a low-K ration to reach a targeted average urine pH between 5.5 and 6.0 (LOW; n = 29, DCAD = -7.4 mEq/100 g of DM). Cows were fed a common postpartum diet and data collected through 63 d in milk. Urine pH (CON = 8.22, MED = 7.89, and LOW = 5.96) was affected quadratically by decreasing prepartum DCAD. A linear relationship between urine pH and urine Ca:creatinine ratio was observed (r = -0.81). Plasma Ca concentrations in the postpartum period (d 0 to 14; CON = 2.16, MED = 2.19, and LOW = 2.27 mmol/L) were increased linearly with decreasing prepartum DCAD. A treatment by parity (second vs. third and greater) interaction for postpartum plasma Ca concentration suggested that older cows had the greatest response to the low DCAD diet and older cows fed LOW had decreased prevalence of hypocalcemia after calving. A quadratic effect of decreasing DCAD on prepartum DMI was observed (CON = 13.6, MED = 14.0, and LOW = 13.2 kg/d). Milk production in the first 3 wk postpartum was increased linearly with decreasing DCAD (CON = 40.8, MED = 42.4, and LOW = 43.9 kg/d) and DMI in this period also tended to linearly increase (CON = 20.2, MED = 20.9, and LOW = 21.3 kg/d). Overall, effects on intake and milk yield analyzed over wk 1 to 9 postpartum were not significant. This study demonstrates that feeding lower DCAD diets prepartum improves plasma Ca status in the immediate postpartum period and results in increased DMI and milk production in the 3 wk after parturition. Compared with no anion supplementation or lower levels of anion supplementation, greater improvements were observed with the lower DCAD feeding strategy, in which an average urine pH of 5.5 to 6.0 was targeted. [ABSTRACT FROM AUTHOR]

Utilizing pasture-based systems may increase cow comfort during late gestation and calving as it lacks the constraints of confinement housing. The objective of this study was to quantify lying behavior and activity of Holstein dairy cows housed on pasture during the 6 d before calving. Sixteen Holstein dairy cows were moved to pasture 3 weeks before their projected calving date. Data loggers were attached 14 d prior to projected calving date. Behavior was evaluated 6 d before calving for all cows (n = 16) and 6 h prior to calving for a subset of cows (n = 6) with known calving times. Data loggers recorded at 1-min intervals to determine lying time (h/d and %/h), lying bouts (n/d and n/h), lying bout duration (min/bout), and steps (n/d and n/h). A repeated measures analysis of variance with contrasts was performed to determine if lying behaviors and activity differed between baseline and day or hour of interest. Lying time was greater 6 d prior to calving compared to the day of and before calving. Cows had longer lying bouts 6 d prior to calving compared to day of calving. Cows spent less time lying in the hour before calving compared to 6 h prior to parturition. The lack of change in behavior and activity during the 7 d prior to calving may indicate that pasture provided an adequate environment for cows during the prepartum period but did not impact cow welfare in the hours leading up to calving. [ABSTRACT FROM AUTHOR]

Precalving feeding level affects dry matter intake, postcalving energy balance, the risk of hepatic lipidosis and metabolic disease, and gene expression in liver and adipose tissue. These coincide with a higher risk of disease postpartum and, very likely, a failure to reach optimum production as well as reproductive targets. Current interpretation of the available evidence suggest that metabolic stressors affect the immune system of transition dairy cows and lead to reduced immunocompetence. The objective of the current study was to investigate the effect of precalving body condition score (BCS) and level of feeding on immunocompetence during the peripartum period. Twenty-three weeks before calving, 78 cows were allocated randomly to 1 of 6 treatment groups (n = 13) in a 2 × 3 factorial arrangement: 2 precalving BCS categories (4.0 and 5.0, based on a 10-point scale) and 3 levels of energy intake during the 3 wk preceding calving (75, 100, and 125% of estimated requirements). Blood was sampled precalving and at 1, 2 and 4 wk after calving. Cells were analyzed by flow cytometry and quantitative real-time PCR. The numbers of T helper lymphocytes (CD4+), cytotoxic T lymphocytes (CD8+), natural killer cells (CD335+), and γδ T lymphocytes (WC1+) as well as their activation status [IL-2 receptor (CD25)+ cells] were highly variable between animals, but there was no evident effect of BCS, feeding level, or time. All groups presented with an increase in expression of cytokines in unstimulated blood cells in the week after calving, although this was significant only for IFNG in the BCS 4.0 group. Analysis of in vitro-stimulated cells allowed 2 general observations: (1) cows with high energy intake precalving (125%) had increased cytokine expression precalving, and (2) all cows had increased cytokine expression in the week after calving. The present study provides evidence that prepartum feed management can affect immunocompetence during the transition period. Considering the current results, optimally conditioned animals might benefit from a restricted precalving diet, whereas underconditioned cows can be fed to requirements. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of partial replacement of barley grain with beet pulp ( BP) on dry matter intake ( DMI), ruminal fermentation, plasma concentration of metabolites and milk yield of transition dairy cows. Twenty-four multiparous Holstein cows [735 ± 26 kg of body weights and 3.5 ± 0.05 of body condition score (BCS)] were used in a randomized complete block design. Cows were assigned randomly on day 28 relative to expected parturition date to one of three treatments containing (i) 0% BP, (ii) 25% BP or (iii) 50% BP substituted for barley grain on a DM basis. During the pre-partum period, DMI and energy intake were greater ( P < 0.01) in cows fed the BP diet compared with cows fed the barley grain diet. During the post-partum period, substituting BP for barley grain caused a response in DMI and energy intake, with the highest amount for the 25% BP diet and lowest for the 50% BP diet ( P < 0.01). Milk yield was lowest ( P < 0.01) for 50% BP diet than the other treatments. During the post-partum period, cows fed the 50% BP diets had greater rumen pH, molar proportion of butyrate and acetate: propionate ratio ( P < 0.01) in the rumen compared with cows fed the 0% BP diets. In addition, cows fed the BP diets had greater ( P < 0.01) plasma β-hydroxybutyrate and lower plasma glucose ( P < 0.05) and blood urinary nitrogen (BUN) ( P < 0.01) concentrations than cows fed the barley grain diets. Results showed that substituting BP for barley grain was effective in increasing DMI, but it did not have a significant effect on net energy balance during the post-partum period. However, replacing BP for barley grain at 50% had adverse effects on DMI, milk yield and metabolic status, as indicated by key blood metabolite concentrations. [ABSTRACT FROM AUTHOR]

Yeast supplementation has been shown to increase feed intake and production in some studies with early lactation dairy cows, but the mechanisms underlying such an effect remain unknown. The objective of this study was to assess the effects of supplementing a yeast product derived from Saccharomyces cerevisiae on production, feeding behavior, and metabolism in cows during the transition to lactation. Forty multiparous Holstein cows were blocked by expected calving date and randomly assigned within block to 1 of 4 treatments (n = 10) from 21 d before expected calving to 42 d postpartum. Rations were top-dressed with a yeast culture plus enzymatically hydrolyzed yeast (YC-EHY; Celmanax, Vi-COR Inc., Mason City, IA) at the rate of 0, 30, 60, or 90 g/d throughout the experiment. Dry matter and water intake, feeding behavior, and milk production were monitored. Plasma samples collected on -21, -7, 1, 4, 7, 14, 21, and 35 d relative to calving were analyzed for glucose, β-hydroxybutyrate, and non-esterified fatty acids. Data were analyzed using mixed models with repeated measures over time. Pre- or postpartum dry matter intake and water intake did not differ among treatments. Quadratic dose effects were observed for prepartum feeding behavior, reflecting decreased meal size, meal length, and intermeal interval, and increased meal frequency for cows received 30 and 60 g/d of YC-EHY. Postpartum feeding behavior was unaffected by treatments. Milk yields were not affected (45.3, 42.6, 47.8, and 46.7 kg/d for 0, 30, 60, and 90 g/d, respectively) by treatments. Tendencies for increased percentages of milk fat, protein, and lactose were detected for cows receiving YC-EHY. Supplementing YC-EHY increased plasma β-hydroxybutyrate and tended to decrease (quadratic dose effect) glucose but did not affect nonesterified fatty acids. Yeast product supplementation during the transition period did not affect milk production and dry matter intake but modulated feeding behavior and metabolism. [ABSTRACT FROM AUTHOR]

Peripartal cows likely require greater amounts of Met not only at the tissue and cell level for methylation reactions but also for milk protein synthesis after calving. Thirty-nine Holstein cows were fed throughout the peripartal period (-21 d to 30 d in milk) a basal control (CON) diet (n = 14) with no Met supplementation, CON plus MetaSmart (MS; Adisseo Inc., Antony, France; n = 12), or CON plus Smartamine M (SM; Adisseo Inc.; n = 13). The Met supplements were adjusted daily and top-dressed over the total mixed ration at a rate of 0.19 or 0.07% (dry matter) of feed for MS or SM. Liver tissue was collected on -10, 7, and 21 d for transcriptome profiling of genes associated with Met and glutathione metabolism as well as components of the inflammation, oxidative stress, growth hormone/insulin-like growth factor-1 axis, and DNA methylation pathways. Data were analyzed using PROC MIXED of SAS (SAS Institute Inc., Cary, NC) with the preplanned contrasts CON versus SM + MS and SM versus MS. The S-adenosylhomocysteine hydrolase (SAHH) gene was the most abundant among all genes evaluated, with overall greater expression in Met-supplemented cows than CON, and in SM than MS. Expression of Met adenosyltransferase 1A (MAT1A) was greater in Met-supplemented cows than CON by 21 d postpartum. A greater overall expression of 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) occurred in Met-supplemented cows than CON. In contrast, the expression of glutathione synthase (GSS); glutamate-cysteine ligase, catalytic subunit (GCLC); and superoxide dismutase 1, cytosolic (SOD1) was lower in Met-supplemented cows than CON. A greater overall expression of nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NFKF11) and greater upregulation of haptoglobin (HP) on d 7 occurred in Met-supplemented cows than CON. Expression of DNA cytosine-5-methyltransferase 3 alpha (DNMT3A) was greater but expression of DNMT1 was lower in Met-supplemented cows than CON. The response observed in SAHH reflects its importance to Met supplementation during the peripartum period. Despite greater HP expression after calving, the lower expression of glutathione (GSS and GCLC) metabolism genes and SOD1 due to Met reflect a lower oxidative stress and mild inflammatory status. The extent to which changes in expression of DNMT3A and DNMT1 result in epigenetic effects partly responsible for the previously observed enhanced performance in Met-supplemented cows remains to be examined. Increasing the supply of Met as SM or MS can affect expression of genes in the Met cycle to various extents and, hence, the supply of methyl donors such as S-adenosylmethionine and anti-oxidants such as glutathione. These compounds likely are in high demand during the peripartum period. [ABSTRACT FROM AUTHOR]

Patatin-like phospholipase domain-containing protein 3 (PNPLA3), commonly known as adiponutrin, is part of a novel subfamily of triglyceride lipase enzymes with potential effects on triglyceride metabolism in adipose and hepatic tissues. The predicted bovine PNPLA3 sequence has been identified, but expression of the gene had not been examined. The objectives of this study were to confirm the predicted bovine PNPLA3 gene sequence, determine expression of the bovine PNPLA3 gene in response to whole-animal energy balance, identify single nucleotide polymorphisms present in dairy cows, and verify the presence of the protein in the liver. Using liver biopsy samples collected from cows at +28 d relative to calving (DRTC), RNA was isolated and used to generate a cDNA template for amplification of the entire predicted coding sequence of PNPLA3 via PCR. To determine if energy balance alters the expression of PNPLA3, RNA was isolated and mRNA expression quantified in liver samples from mid-lactation cows after a 5-d ad libitum period (n = 5) and after a subsequent 5-d 50% feed restriction period (n = 5), and in samples collected from cows at -- 14, +1, +14, and +28 DRTC (n = 16). The presence of PNPLA3 protein was detected by Western blot in liver protein samples collected at +28 DRTC. Expression of hepatic PNPLA3 was decreased after a period of feed restriction (8.14 vs. 1.08 ± 2.17 arbitrary units, ad libitum vs. fasted). Expression of PNPLA3 mRNA was decreased at +1 and +14 DRTC compared with -14 DRTC (23.35, 7.28, 10.17, and 14.5 ± 4.9 arbitrary units, -14, +1, +14, and +28 DRTC, respectively). The presence of PNPLA3 protein was detected as a 55-kDa band in hepatic protein isolations from liver tissue collected at +28 DRTC. These data confirm the presence and sequence of the bovine hepatic PNPLA3 gene and single nucleotide polymorphisms. Furthermore, these data indicate responsiveness of bovine hepatic PNPLA3 to energy balance. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the effect of calving body condition score (BCS) on cow health during the transition period in a pasture-based dairying system. Feed inputs were managed during the second half of the previous lactation so that BCS differed at drying off (BCS 5.0, 4.0, and 3.0 for high, medium, and low treatments, respectively: a 10-point scale); feed allowance was managed after cows were dried off, such that the BCS differences established during lactation remained at the subsequent calving (BCS 5.5, 4.5, and 3.5; n = 20, 18, and 19, for high, medium, and low treatments, respectively). After calving, cows were allocated pasture and pasture silage to ensure grazing residuals >1,600 kg of DM/ha. Milk production was measured weekly; blood was sampled regularly pre- and postpartum to measure indicators of health, and udder and uterine health were evaluated during the 6 wk after calving. Milk weight, fat, protein, and lactose yields, and fat content increased with calving BCS during the first 6 wk of lactation. The effect of calving BCS on the metabolic profile was nonlinear. Before calving, cows in the low group had lower mean plasma β-hydroxybutyrate and serum Mg concentrations and greater mean serum urea than cows in the medium and high BCS groups, which did not differ from each other. During the 6 wk after calving, cows in the low group had lower serum albumin and fructosamine concentrations than cows in the other 2 treatment groups, whereas cows in the low- and medium-BCS groups had proportionately more polymorphonucleated cells in their uterine secretions at 3 and 5 wk postpartum than high-BCS cows. In comparison, plasma β-hydroxybutyrate and nonesterified fatty acid concentrations increased linearly in early lactation with calving BCS, consistent with a greater negative energy balance in these cows. Many of the parameters measured did not vary with BCS. The results highlight that calving BCS and, therefore, BCS through early lactation are not effective indicators of functional welfare, with the analyses presented indicating that both low and high BCS at calving will increase the risk of disease: cows in the low group were more prone to reproductive compromise and fatter cows had an increased risk of metabolic diseases. These results are important in defining the welfare consequences of cow BCS. [ABSTRACT FROM AUTHOR]

The effects of a dietary supplement of rumen-protected choline on feed intake, milk yield, milk composition, blood metabolites, and hepatic triacylglycerol were evaluated in periparturient dairy cows. Thirty-eight multiparous cows were blocked into 19 pairs and then randomly allocated to either one of 2 treatments. The treatments were supplementation either with or without (control) rumen-protected choline. Treatments were applied from 3 wk before until 6 wk after calving. Both groups received the same basal diet, being a mixed feed of grass silage, corn silage, straw, and soybean meal, and a concentrate mixture delivered through transponder-controlled feed dispensers. For all cows, the concentrate mixture was gradually increased from 0 kg/day (wk -3) to 0.9 kg of dry matter (DM)/d (day of calving) and up to 8.1 kg of DM/d on d 17 postcalving until the end of the experiment. Additionally, a mixture of 60 g of a rumen-protected choline supplement (providing 14.4 g of choline) and of 540 g of soybean meal or a (isoenergetic) mixture of 18 g of palm oil and 582 g of soybean meal (control) was offered individually in feed dispensers. Individual feed intake, milk yield, and body weight were recorded daily. Milk samples were analyzed weekly for fat, protein, and lactose content. Blood was sampled at wk -3, d 1, d 4, d 7, d 10, wk 2, wk 3, and wk 6 and analyzed for glucose, nonesterified fatty acids, and β-hydroxybutyric acid. Liver biopsies were taken from 8 randomly selected pairs of cows at wk -3, wk 1, wk 4, and wk 6 and analyzed for triacylglycerol concentration. We found that choline supplementation increased DM intake from 14.4 to 16.0 kg/d and, hence, net energy intake from 98.2 to 109.1 MJ/d at the intercept of the lactation curve at 1 day in milk (DIM), but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation had no effect on milk yield, milk fat yield, or lactose yield. Milk protein yield was increased from 1.13 to 1.26 kg/d at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation was associated with decreased milk fat concentration at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk fat concentration gradually decreased as lactation progressed. Choline supplementation had no effect on energy-corrected milk yield, energy balance, body weight, body condition score, and measured blood parameters. Choline supplementation decreased the concentration of liver triacylglycerol during the first 4 wk after parturition. Results from this study suggest that hepatic fat export in periparturient dairy cows is improved by choline supplementation during the transition period and this may potentially decrease the risk for metabolic disorders in the periparturient dairy cow. [ABSTRACT FROM AUTHOR]

Thiazolidinediones (TZD) are potent synthetic ligands for peroxisome proliferator-activated receptor-γ that have been shown previously to reduce plasma nonesterified fatty acids and increase peripartal dry matter intake (DMI) in dairy cows. Data from Holstein cows (n = 36) entering their second or greater lactation were used to determine whether late prepartum administration of TZD would affect periparturient metabolism, milk production, and ovarian activity. Cows were administered 0, 2.0, or 4.0 mg of TZD/kg of BW by intrajugular infusion once daily from 21 d before expected parturition until parturition. Plasma samples were collected daily from 22 d before expected parturition through 21 d postpartum and twice weekly from wk 4 through 9 postpartum. In response to increasing TZD dosage, plasma nonesterified fatty acid concentrations decreased linearly during the postpartum period (d 0 to +21: 348, 331, 268 ± 31 μEq/L, respectively). Plasma concentrations of glucose were highest in cows administered 4.0 mg of TZD/kg of BW during the peripartum and postpartum periods (d -7 to +7: 57.9, 57.8, 61.1 ± 0.8 mg/dL and d 0 to +21: 51.6, 49.3, 54.7 ± 1.1 mg/dL, respectively). Plasma concentrations of β-hydroxybutyrate were increased during the peripartum period by TZD administration (9.6, 9.9, 10.2 ± 0.3 mg/dL) but were not affected during the postpartum period. Plasma insulin was not affected by treatment during any time period. Postpartum liver triglyceride content was decreased linearly (11.0, 10.4, 4.2 ± 1.6%) and glycogen content was increased linearly (2.16, 2.38, 2.79 ± 0.19%) by prepartum TZD administration. Prepartum TZD administration linearly increased DMI during the peripartum period (d -7 to +7: 16.1, 17.2, 17.3 ± 0.5 kg/d). Cows administered TZD prepartum maintained higher postpartum body condition scores than control cows (wk 1 through 9: 2.77, 2.89, 3.02 ± 0.05). There was no effect of prepartum TZD on milk yield; however, yields of 3.5% fat-corrected milk (52.2, 54.6, 48.0 ± 1.6 kg/d) and most other milk components were decreased in cows that received 4.0 mg of TZD/ kg of BW prepartum. Prepartum TZD administration linearly decreased the number of days to first ovulation (29.3, 28.3, 19.0 ± 3.6 d). These results suggest that prepartum administration of TZD improves metabolic health and DMI of periparturient dairy cows and may decrease reliance on body fat reserves during early lactation. [ABSTRACT FROM AUTHOR]

Eighty multiparous cows were used to test the effects of feeding a supplement containing 55% dry propylene glycol (PGLY), prilled fat (PrFA) containing a low proportion of unsaturated fatty acids (FA), or calcium soaps of long-chain FA (CaLFA) containing a high proportion of unsaturated FA on energy balance (EB), blood metabolites, and early postpartum (PP) ovarian follicles. Dry cows (256 d pregnant) were divided into 6 groups and began the following dietary treatments: 1) control group, fed a dry cow diet and fed a lactating cow diet PP; 2) PGLY group, diet supplemented with 500 g/d per cow of dry PGLY prepartum through 21 d in milk; 3) PrFA:control group, diet supplemented with 230 g/ d per cow of PrFA prepartum and fed the control diet PP; 4) PrFA:PrFA group, diet supplemented with 230 g/d per cow of PrFA prepartum through 21 d in milk; 5) CaLFA:control, supplemented with 215 g/d per cow of CaLFA prepartum and fed the control diet PP; 6) CaLFA:CaLFA, supplemented with 215 g/d per cow of CaLFA prepartum through 21 d in milk. Follicular fluid was aspirated from follicles ≥6 mm on d 12 PP. The daily average calculated EB during the first 21 d in milk was lower in the PrFA:PrFA (-4.16 Mcal/d) and CaLFA:CaLFA (-3.64 Mcal/d) groups than in the control (-1.71 Mcal/d) and PGLY (-2.19 Mcal/d) groups. Postpartum plasma β-hydroxybutyrate was higher, and insulin concentrations were lower in the PrFA:PrFA (6.2 mg/dL and 126.1 pg/mL, respectively) and CaLFA:CaLFA (7.0 mg/dL and 130.7 pg/mL) groups than in the control (4.5 mg/dL and 274.5 pg/mL) and PGLY (4.3 mg/dL and 272.6 pg/mL) groups, whereas nonesterified FA concentrations were higher only than the control group. Postpartum nonesterified FA were 21% lower and insulin plasma concentrations were 86% higher in the CaLFA:control group as compared with the PrFA:control group. The progesterone concentrations in the follicular fluid of estradiol-active follicles were higher in the CaLFA:CaLFA (200.7 ng/mL) group than in all other groups (57.3 to 92.4 ng/mL), and andros-tenedione and estradiol concentrations were higher (54.2 and 1,049.1 ng/mL, respectively) than in the PGLY (15.5 and 440.1 ng/mL), PrFA:control (22.6 and 314.1 ng/mL), and CaLFA:control (17.5 and 451.9 ng/ mL) groups. In conclusion, supplementation of protected fat during the peripartum period negatively affected the EB status of the cows. Neither fat supplementation nor PGLY influenced the development of ovarian follicles during the early PP period, but feeding fat containing a high ratio of unsaturated FA (CaLFA) increased progesterone concentrations in estradiol-active follicles that were aspirated at 12 d in milk. [ABSTRACT FROM AUTHOR]

Seventeen multiparous Holstein cows were used to examine the effect of an increased duodenal supply of Gln on immune function and production. Cows received continuous abomasal infusions of water (control: n = 8) or 300 g/d of Gln (n = 9) for 21 d starting within 48 h of calving. There were nonsignificant increases in milk and milk protein yields in response to Gln supplementation. Glutamine treatment had no effect on plasma glucose, nonesterified fatty acids (NEFA), or β-hydroxybutyrate (BHBA) concentrations but did tend to increase plasma urea N concentration. The Gln treatment resulted in an increase of 108 µM in the plasma Gln concentration. Total essential AA concentrations decreased with the Gln treatment, whereas total nonessential AA concentrations were unaffected. T Lymphocyte proliferation did not differ between the control and Gin-treated cows. Treatment had no effect on the relative abundance of CD8 T cells but did increase the abundance of CD4 T cells. Cytokine production, as measured by IFN-γ concentration determined in vitro in concanavalin-A-stimulated peripheral blood mononuclear cells, was similar between the treatments. Over the first 3 wk following calving, Gln supplementation had limited effects on milk production, metabolic parameters, and immune function. [ABSTRACT FROM AUTHOR]

The objective of the present study was to quantify the climatic, animal, and management factors influencing incidence of milk fever (MF) in cows exposed to grazing systems. Data were extracted on 4,469 calvings of multiparous cows in a seasonal calving research herd between 1970 and 2000. Climatic data during the calving period also were extracted for these years. Poisson regression was used to investigate the effect of climate on frequency of MF within year; the offset variable was the number of cows at risk for MF at that time. Generalized estimating equations, with cow included as a repeated effect, were used to quantify the effect of parturition-associated cow and management factors on the logit of the probability of MF. Both univariate and multivariate analyses were performed. Explanatory variables investigated included time of calving relative to the herd-year calving period, parity, body weight, breed of cow, body condition score at calving, weight and gender of the calf, incidence of twin calves, calving inductions, and calving assistance. Odds of recurring MF within cow, as well as the timing of MF relative to day of calving, was quantified using generalized estimating equations with cow included as a repeated effect. Results show significant effects of evaporation, minimum grass temperature, difference between ambient maximum and minimum temperature, and rainfall on the odds of MF occurring, with a greater incidence at greater evaporation, larger diurnal variation in air temperature, greater rainfall, and lesser grass minimum temperature. Cow factors, such as age, excessive or poor body condition score, and requirement for calving assistance increased the odds of MF; a lesser odds ratio was observed in cows hormonally induced to calve and those that had twin births. Results indicate that herd managers may identify the day of greatest risk for MF and cows that are at greatest risk of MF based on climatic, cow, and management factors. [ABSTRACT FROM AUTHOR]

Presents abstracts of studies regarding the ruminant nutrition of transition cows. "Altered Feeding Behavior Occurs in Both Primiparous and Multiparous Holsteins During the Periparturient Period," by M.A. DeGroot and P.D. French; "The Effect of Prepartum Monensin Supplementation on Milk Production in Dairy Cows," by A. Arieli and U. Dicken; "Effect of Lowered Prepartum DCAD on Urinary pH: A Meta-Analysis," by E. Charbonneau, D. Pellerin and G.R. Oetazel.

Presents abstracts of studies regarding the ruminant nutrition of transition cows. "Altered Feeding Behavior Occurs in Both Primiparous and Multiparous Holsteins During the Periparturient Period," by M.A. DeGroot and P.D. French; "The Effect of Prepartum Monensin Supplementation on Milk Production in Dairy Cows," by A. Arieli and U. Dicken; "Effect of Lowered Prepartum DCAD on Urinary pH: A Meta-Analysis," by E. Charbonneau, D. Pellerin and G.R. Oetazel.

Presents abstracts of studies regarding the ruminant nutrition of transition cows. "Altered Feeding Behavior Occurs in Both Primiparous and Multiparous Holsteins During the Periparturient Period," by M.A. DeGroot and P.D. French; "The Effect of Prepartum Monensin Supplementation on Milk Production in Dairy Cows," by A. Arieli and U. Dicken; "Effect of Lowered Prepartum DCAD on Urinary pH: A Meta-Analysis," by E. Charbonneau, D. Pellerin and G.R. Oetazel.