Symposium review: Predicting pregnancy loss in dairy cattle Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): Alan D. Ealy, Zachary K. Seekford ABSTRACT Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure.

Energy profiling of dairy cows from routine milk mid-infrared analysis Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): S.L. Smith, S.J. Denholm, M.P. Coffey, E. Wall ABSTRACT The balance of body energy within and across lactations can have health and fertility consequences for the dairy cow. This study aimed to create a large calibration data set of dairy cow body energy traits across the cow's productive life, with concurrent milk mid-infrared (MIR) spectral data, to generate a prediction tool for use in commercial dairy herds. Detailed phenotypic data from 1,101 Holstein Friesian cows from the Langhill research herd (SRUC, Scotland) were used to generate energy balance (EB) and effective energy intake (EI), both in megajoules per day. Pretreatment of spectral data involved standardization to account for drift over time and machine. Body energy estimates were aligned with their spectral data to generate a prediction of these traits based on milk MIR spectroscopy. After data edits, partial least squares analysis generated prediction equations with a coefficient of determination from split sample 10-fold cross validation of 0.77 and 0.75 for EB and EI, respectively. These prediction equations were applied to national milk MIR spectra on over 11 million animal test dates (January 2013 to December 2016) from 4,453 farms. The predictions generated from these were subject to phenotypic analyses with a fixed regression model highlighting differences between the main dairy breeds in terms of energy traits. Genetic analyses generated heritability estimates for EB and EI ranging from 0.12 to 0.17 and 0.13 to 0.15, respectively. This study shows that MIR-based predictions from routinely collected national data can be used to generate predictions of dairy cow energy turnover profiles for both animal management and genetic improvement of such difficult and expensive-to-record traits.

Mammalian target of rapamycin signaling and ubiquitin-proteasome–related gene expression in skeletal muscle of dairy cows with high or normal body condition score around calving Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): M.H. Ghaffari, K. Schuh, G. Dusel, D. Frieten, C. Koch, C. Prehn, J. Adamski, H. Sauerwein, H. Sadri ABSTRACT 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.

Methane emissions of manure from dairy cows fed red clover- or corn silage-based diets supplemented with linseed oil Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): F. Hassanat, C. Benchaar ABSTRACT The objective of this study was to investigate the effects of forage source (red clover silage: RCS vs. corn silage: CS) and diet supplementation with linseed oil (LO) on CH4 emissions of manure from dairy cows. For this purpose, 12 lactating cows were used in a 2 × 2 factorial arrangement of treatments. Cows were fed (ad libitum) RCS- or CS-based diets (forage:concentrate ratio 60:40; dry matter basis) without or with LO addition (4% dry matter). Feces and urine were collected from each cow and mixed with residual sludge obtained from a manure storage structure. Manure was incubated for 17 wk at 20°C under anaerobic conditions (O2-free N2) in 500-mL glass bottles. Methane emissions and changes in chemical composition of the manure were monitored during the entire incubation period. The total amount of feces and urine excreted by cows was not affected by dietary treatments and averaged 6.6 kg/d of volatile solids (VS). Compared with manure from cows fed RCS-based diets, maximum CH4 production potential of manure from cows fed CS-based diets was 54% higher (182 vs. 118 L/kg of VS) throughout the incubation period. Maximum CH4 production potential from manure also increased (by 17%) when cows were fed LO-supplemented diets compared with those fed nonsupplemented diets. Similar to maximum CH4 production potential, VS degraded during incubation (i.e., VS loss) was higher from manure from cows fed CS-based diets versus cows fed RCS-based diets (30.6 vs. 22.5%), and increased (+3 percentage units, on average) with the addition of LO to the diets. Ammonia concentration in manure was higher when cows were fed CS-based diets compared with RCS-based diets, and declined with LO supplementation to CS and RCS diets. It is concluded that both dietary forage source and fat supplementation affect maximum CH4 production potential from manure and this should be taken into account when such dietary options are recommended to mitigate enteric CH4 emissions from dairy cows.

Short communication: Detection of antibiotic resistance, mecA, and virulence genes in coagulase-negative Staphylococcus spp. from buffalo milk and the milking environment Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): Lucas J.L. Pizauro, Camila C. de Almeida, Glenn A. Soltes, Durda Slavic, Fernando A. de Ávila, Luiz F. Zafalon, Janet I. MacInnes ABSTRACT The aim of this study was to determinate whether coagulase-negative staphylococci (CNS) from buffalo milk or the milking environment possess virulence factors that are associated with intramammary infections or antimicrobial resistance. Milk samples (n = 320) from 80 lactating buffalo were evaluated for clinical and subclinical mastitis by physical examination, the strip cup test, California Mastitis Test (CMT), and somatic cell count (SCC) over a 4-mo period. In addition, swabs were obtained from the hands of consenting milkers (16), liners (64), and from the mouths (15) and nostrils (15) of buffalo calves. No clinical cases of mastitis were observed; however, CMT together with SCC results indicated that 8 animals had subclinical mastitis. Eighty-four CNS isolates were identified by MALDI-TOF MS and cydB real-time PCR (qPCR) and then evaluated by qPCR for presence of the eta, etb, sea, sec, cna, seb, sei, seq, sem, seg, see, and tst toxin genes, adhesion- and biofilm-associated genes (eno, ebps, fib, fnbA, coa), and the methicillin resistance gene (mecA). Resistance to antibiotics commonly used for mastitis treatment in Brazil was determined using the Kirby-Bauer test. Two strains were positive for the see and eta toxin genes; and mecA (1), eno (27), ebps (10), fnbA (10), and coa (5) genes were also detected. A notable number of isolates were resistant to erythromycin (30), penicillin (26), and cotrimoxazole (18); importantly, 10 vancomycin-resistant isolates were also detected. A smaller number of isolates were resistant to rifampicin (8), oxacillin (7), clindamycin (5), cefepime (4), tetracycline (3), ciprofloxacin (2), and chloramphenicol (1), and none were resistant to gentamicin or ciprofloxacin. Isolates with resistance to 2 (13 isolates), 3 (3), 4 (3), 5 (1), and 6 (1) antibiotics were detected. Taken together, our findings suggest that CNS isolates may not be a significant cause of clinical or even subclinical mastitis in buffaloes, but they may be a reservoir of virulence and antibiotic resistance genes.

Short communication: Production performance and nutrient digestibility of lactating dairy cows fed diets with and without addition of a live-yeast supplement Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): G. Ferreira ABSTRACT The objective of this study was to evaluate the use of a live-yeast product when feeding relatively high-forage diets to high-producing cows in mid lactation. Eight primiparous [607 ± 43 kg of body weight (BW) and 130 ± 16 d in milk (DIM) at the beginning of the experiment] and 16 multiparous (706 ± 63 kg of BW and 137 ± 22 DIM at the beginning of the experiment) Holstein cows were blocked by parity and DIM, and randomly assigned to 1 of 2 diets (control vs. yeast) for a 12-wk period according to a randomized complete block design. The formulated diets contained 50.4% corn silage, 10.4% alfalfa hay, and 39.2% concentrate. The yeast diet was formulated to provide approximately 5.4 × 1011 cfu/d of Saccharomyces cerevisiae (BeneSacc; Global Nutritech Biotechnology LLC, Richmond, VA). Total-tract nutrient digestibility was estimated using 240-h undigested neutral detergent fiber (NDF) as an internal marker. Supplementing live yeast to lactating dairy cows did not affect dry matter intake (25.0 kg/d), milk yield (38.6 kg/d), milk fat concentration (4.78%), milk fat yield (1.83 kg/d), milk protein concentration (3.09%), milk protein yield (1.18 kg/d), milk lactose concentration (4.79%), milk lactose yield (1.84 kg/d), BW gain (−0.05 kg/d), or body condition score gain (0.16 units). The digestibility of dry matter was greater for the control treatment than for the yeast treatment (69.3 and 67.1%, respectively), but the digestibilities of crude protein (61.5%), NDF (40.5%), and starch (98.6%) were not affected by treatment. In conclusion, supplementation of live yeast did not affect production performance or nutrient digestibility of high-producing cows in mid lactation. The reasons for the lack of effect are not clear, but an evaluation of interactions between yeast and rumen buffer supplementation is warranted.

A goal programming approach for balancing diet costs and feed water use under different environmental conditions Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): J. Qu, T.C. Hsiao, E.J. DePeters, D. Zaccaria, R.L. Snyder, J.G. Fadel ABSTRACT Water is essential in livestock production systems. In typical dairy production systems, 90% of the total water used by a dairy farm is attributed to feed production. Theoretically, ration manipulation is a method to potentially reduce the irrigation water needed for feed crops without dramatically increasing diet costs. However, published quantitative studies on the relationship between feed production and water use that are integrated with linear programming models are scarce. The overall objective of this study was to develop an optimization framework that could achieve a balance between minimization of dietary costs and dietary irrigation water usage, and that could be used as a framework for future research and models for various livestock production systems. Weighted goal programming models were developed to minimize the dietary costs and irrigation water usage for a hypothetical cow under 8 different environmental scenarios. The environmental conditions used a 2 × 2 × 2 factorial design, including 2 atmospheric CO2 concentrations (400 and 550 ppm), 2 water years (dry and wet), and 2 irrigation methods (furrow and drip). A systematic weighting scheme was used to model the trade-off between minimizing diet cost and minimizing irrigation water use for feedstuffs. Each environmental condition generated a set of distinct diets, which each met the same nutrient requirements of the hypothetical cow but had a different water usage when the weighting scheme was changed from weighting minimum diet costs to minimum irrigation water usage. For water resource planning in areas of dairy production, this set of unique solutions provides the decision maker with different feeding options according to diet cost, water usage, and available feeds. As water was more constrained, dietary dry matter intake increased, concentrations of neutral detergent fiber, ether extract, and energy decreased, and the concentration of lignin increased because less nutritive but more water-saving feedstuffs were included in the diet. Mitigation costs of water usage were calculated from goal programming results and indicated that the potential value of water under water-limited conditions (e.g., in a drought region) was higher than that under water-sufficient conditions. However, a smaller increase in feed costs can initially significantly reduce water usage compared with that of a least-cost diet, which implies that the reduction of water usage through ration manipulation might be possible. This model serves as a framework for the study of irrigation water usage in dairy production and other livestock production systems and for decision-making processes involved in water resources planning in the broader area of animal production.

Phenotypic and genetic analysis of milk and serum element concentrations in dairy cows Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): Scott J. Denholm, Alan A. Sneddon, Tom N. McNeilly, Shabina Bashir, Mairi C. Mitchell, Eileen Wall ABSTRACT Enhancing micronutrient (i.e., mineral and vitamin) concentrations within milk and serum from dairy cows is important for both the health of the cow and the nutritive value of the milk for human consumption. However, a good understanding of the genetics underlying the micronutrient content in dairy cattle is needed to facilitate such enhancements through feeding or breeding practices. In this study, milk (n = 950) and serum (n = 766) samples were collected from Holstein-Friesian dairy cows (n = 479) on 19 occasions over a 59-mo period and analyzed for concentrations of important elements. Additionally, a subset of 256 milk samples was analyzed for concentrations of vitamin B12. Cows belonged to 2 genetic lines (average and highest genetic merit for milk fat plus protein yield) and were assigned to 1 of 2 diets based on either a by-product or homegrown ration. Univariate models accounting for repeated records were used to analyze element and vitamin B12 data and investigate the effect of genotype and feeding system as well as derive estimates of variance components and genetic parameters. Bivariate models were used to study correlations both within and between milk and serum. Only concentrations of Hg in milk were seen to be affected by genotype, with higher concentrations in cows with high genetic merit. In contrast, element concentrations were influenced by feeding system such that cows fed the homegrown diet had increased milk concentrations of Ca, Cu, I, Mn, Mo, P, and K and increased serum concentrations of Cd, Cu, Fe, Mo, and V. Cows on the by-product diet had increased milk concentrations of Mg, Se, and Na and increased serum concentrations of P and Se. Heritability (h2) estimates were obtained for 6 milk and 4 serum elements, including Mg (h2milk = 0.30), K (h2serum = 0.18), Ca (h2milk = 0.20; h2serum = 0.12), Mn (h2milk = 0.14), Cu (h2serum = 0.22), Zn (h2milk = 0.24), Se (h2milk = 0.15; h2serum = 0.10), and Mo (h2milk = 0.19). Significant estimates of repeatability were observed in all milk and serum quantity elements (Na, Mg, P, K, and Ca) as well as 5 milk and 7 serum trace elements. Only K in milk and serum was found to have a significant positive genetic and phenotypic correlation (0.52 and 0.22, respectively). Significant phenotypic associations were noted between milk and serum Ca (0.17), Mo (0.19), and Na (−0.79). Additional multivariate analyses between measures within sample type (i.e., milk or serum) revealed significant positive associations, both phenotypic and genetic, between some of the elements. In milk, Se was genetically correlated with Ca (0.63), Mg (0.59), Mn (0.40), P (0.53), and Zn (0.52), whereas in serum, V showed strong genetic associations with Cd (0.71), Ca (0.53), Mn (0.63), Mo (0.57), P (0.42), K (0.45), and Hg (−0.44). These results provide evidence that element concentrations in milk and blood of dairy cows are significantly influenced by both diet and genetics and demonstrate the potential for genetic selection and dietary manipulation to alter nutrient concentration to improve both cow health and the healthfulness of milk for human consumption.

Persistence of differences between dairy cows categorized as low or high methane emitters, as estimated from milk mid-infrared spectra and measured by GreenFeed Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): T.M. Denninger, F. Dohme-Meier, L. Eggerschwiler, A. Vanlierde, F. Grandl, B. Gredler, M. Kreuzer, A. Schwarm, A. Münger ABSTRACT Currently, various attempts are being made to implement breeding schemes aimed at producing low methane (CH4) emitting cows. We investigated the persistence of differences in CH4 emission between groups of cows categorized as either low or high emitters over a 5-mo period. Two feeding regimens (pasture vs. indoors) were used. Early- to mid-lactation Holstein Friesian cows were categorized as low or high emitters (n = 10 each) retrospectively, using predictions from milk mid-infrared (MIR) spectra, before the start of the experiment. Data from MIR estimates and from measurements with the GreenFeed (GF; C-Lock Technology Inc., Rapid City, SD) system over the 5-mo experiment were combined into 7-, 14-, and 28-d periods. Feed intake, eating and ruminating behavior, and ruminal fluid traits were determined in two 7-d measurement periods in the grazing season. The CH4 emission data were analyzed using a split-plot ANOVA, and the repeatability of each of the applied methods for determining CH4 emission was calculated. Traits other than CH4 emission were analyzed for differences between low and high emitters using a linear mixed model. The initial category-dependent differences in daily CH4 production persisted over the subsequent 5 mo and across 2 feeding regimens with both methods. The repeatability analysis indicated that the biweekly milk control scheme, and even a monthly scheme as practiced on farms, might be sufficient for confirming category differences. However, the relationship between CH4 data estimated by MIR and measured with GF for individual cows was weak (R2 = 0.26). The categorization based on CH4 production also generated differences in CH4 emission per kilogram of milk; differentiation between cow categories was not persistent based on milk MIR spectra and GF. Compared with the high emitters, low emitters tended to show a lower acetate-to-propionate ratio in ruminal volatile fatty acids, whereas feed intake and ruminating time did not differ. Interestingly, the low emitters spent less time eating than the high emitters. In conclusion, the CH4 estimation from analyzing the milk MIR spectra is an appropriate proxy to form and regularly control categories of cows with different CH4 production levels. The categorization was also sufficient to secure similar and persistent differences in emission intensity when estimated by MIR spectra of the milk. Further studies are needed to determine whether MIR data from individual cows are sufficiently accurate for breeding.

Effects of colostrum and milk replacer feeding rates on intake, growth, and digestibility in calves Publication date: Available online 3 October 2019 Source: Journal of Dairy Science Author(s): J.D. Quigley, L. Deikun, T.M. Hill, F.X. Suarez-Mena, T.S. Dennis, W. Hu ABSTRACT Newborn Holstein male calves (n = 50) born on a single dairy farm were assigned randomly at birth to receive 3 feedings of 1.8 L of pooled maternal colostrum (MC) at 1, 6, and 12 h of age or 1 feeding of 500 g of a colostrum replacer reconstituted to 1.8 L at 1 h of age, followed by 2 feedings of 227 g of a commercial milk replacer (MR) reconstituted to 1.8 L at 6 and 12 h of age (CR). All feedings were administered by esophageal feeder. At 2 to 3 d of age, calves were transported to the experimental facility and assigned within colostrum group to receive 0.66 kg/d dry matter (DM) of MR to 39 d, and then 0.33 kg/d to 42 d (MRM) or 0.77 kg/d of MR DM to d 13, 1.03 kg/d for 22 d, and 0.51 kg/d for 7 d (MRH). The MR contained 25.8% crude protein and 17.6% crude fat (DM basis) and was based on whey proteins and lard as the primary fat source. Calf starter (21.7% crude protein, 15.7% neutral detergent fiber, 37.4% starch, DM basis) and water were available for ad libitum consumption throughout the 56-d study. Serum IgG and total protein were measured at 2 to 3 d of age. Intakes of MR and calf starter were monitored daily. Calf health and fecal scores were also monitored daily. Body weight was measured weekly, and hip width and body condition score were monitored every 2 wk. Digestion of DM, organic matter, crude protein, and ether extract were determined at 1 and 3 wk from 5 calves randomly selected within treatment and using chromic oxide as a digestibility marker added to the MR. Calves fed CR had lower serum IgG and total protein than calves fed MC. Also, calves fed CR grew more slowly, consumed less calf starter, and were less efficient to 56 d than calves fed MC. The number of days calves were treated with veterinary medications was higher when calves were fed CR. Calves fed MC-MRH gained more BW than other calves from 3 to 8 wk of age. Calves fed CR-MRH consumed less calf starter than other calves during wk 7 and 8. Digestion of nutrients at 1 and 3 wk of the study was unaffected by type of colostrum or level of MR fed and did not change from 1 to 3 wk. Over the first 2 mo of life, the calves fed MRH consumed less calf starter than calves fed MRM, but average daily gain or hip width change did not differ. One feeding of CR followed by 2 feedings of MR in the first 24 h likely reduced absorption of IgG from CR and contributed to differences in health and growth. Differences in animal performance observed in this study were unrelated to MR digestibility.