[This corrects the article DOI: 10.3168/jdsc.2024-0668.].
This study aimed to evaluate the effect of genotyping errors on indirect predictions (IP). For that, we simulated a dairy cattle population with 5 replicates, using QMSim. Benchmark GEBV for young animals (n = 11,250) were computed using a full single-step genomic BLUP (generations 11-15). Three SNP error rates (5%, 10%, and 20%) were applied to the genotypes of selection candidates (generation 15). A reduced analysis with generations 11 to 14 (44,500 animals) was conducted to obtain SNP solutions for computing IP in young animals using either the correct genotype files or files with genotyping errors. The average IP values decreased as the error rate increased. The correlation between the benchmark GEBV and the IP obtained with the correct genotype was 0.98 ± 0.01. As expected, this correlation decreased with increasing genotyping errors, reaching its lowest value (0.93) at 20% errors. The regression coefficient of GEBV on IP increased (i.e., more underdispersed breeding values) as the error rate increased: b1 moved away from 1.01 ± 0.02 (no errors) to 1.33 ± 0.03 (20% errors). Results of this study highlight the importance of accurate genotype calls to achieve precise and unbiased IP when performing IP for young animals with genotypes.
Animal management and environmental conditions influence milk composition and processing properties. Seasonal calving systems are used in milk production to optimize costs and align milk supply with forage availability; however, the effects of concentrating calvings in fall and winter, compared with extended calving, on milk composition and heat coagulation time (HCT) have not been clearly defined. The objective of this study was to evaluate whether calving strategy affects milk composition and HCT in a pasture-based dairy system. Thirty New Zealand Holstein cows were assigned to 3 calving systems-extended (EXT: March-October, spanning fall-winter with calvings distributed across both seasons), winter seasonal (WIN: June-August, concentrated in winter), and fall seasonal (FC: March-May, concentrated in fall)-with 10 cows per system, and monitored over one production year. Composite milk samples were collected in 4 seasonal windows (spring, summer, fall, and winter) and analyzed for composition (protein, casein, TS, SNF, urea, citric acid, lactose, and titratable acidity) and heat stability, assessed both as HCT at native pH and as HCT-pH profiles after adjustment to target pH values from 6.5 to 7.0. No single compositional variable consistently explained the observed HCT patterns across calving systems and seasons. In pooled linear regression models, HCT was positively associated with grazed pasture in the diet and days in milk, and negatively associated with DMI. These findings highlight the complexity of milk heat stability under pasture-based conditions and indicate that more detailed studies are needed to identify robust predictors of HCT.
This study aimed to evaluate the associations of diarrhea frequency on intestinal permeability, plasma glucagon-like peptide-2 (GLP-2) concentration, and growth performance in dairy calves. Twenty-two Holstein calves were monitored from birth to postweaning and classified into high (H) and low (L) diarrhea groups based on the number of days with diarrhea (top and bottom 25%, respectively: n = 6). Fecal consistency was scored on a 4-point scale ranging from 0 to 3, and diarrhea was defined as a fecal score ≥2, with total days of diarrhea ranging from 19 to 36 d in the H group and from 3 to 5 d in the L group throughout the 66-d experimental period. To evaluate the intestinal permeability, the Cr-EDTA test was assessed by oral administration of Cr-EDTA followed by blood sample collections at 28, 42, and 63 d of age. At 0, 1, 5, 28, 42, 49, 56, and 66 d of age, blood GLP-2 concentrations were measured. Although no differences in intestinal permeability were detected between groups, plasma GLP-2 concentrations were consistently higher in the L group throughout the observation period. In addition, despite no differences in solid feed intake between groups, ADG was greater in the L group than in the H group. These findings suggest that plasma GLP-2 concentrations may be associated with postweaning ADG, even in the absence of detectable changes in intestinal permeability.
Highly pathogenic avian influenza H5N1 has infected US dairy cattle and spread throughout 19 different states since March 2024. Although within-farm transmission is thought to occur primarily through direct contact, local between-farm spread remains unknown, and is considered multifactorial and likely driven by routine business activities involving shared personnel, vehicles, and other conveyances. This investigation evaluated the presence of influenza A virus RNA in a convenience sample of milk transport trucks and other on-farm service vehicles in H5N1-affected areas in 3 states between May 2024 and April 2025. A total of 298 samples were collected from 52 vehicles, of which 38 were milk trucks and tankers from 2 dairy cooperatives. Influenza A virus RNA was detected in 1.3% (4/298) of samples: 2 from tires on a livestock hauler and a deadstock trailer in Michigan, 1 from a milk cabinet sample from a milk tanker in Michigan, and 1 from a tanker milk sample in California. Although a very small percentage of samples were positive, this investigation shows that H5N1 virus can be detected on vehicles servicing US dairy herds, highlighting a potential pathway for between-farm transmission.
Methane (CH4) inhibitor 3-nitrooxypropanol (3-NOP) shows variable efficacy in Brown Swiss (BS) and Holstein (HF) cows, but the underlying mechanisms remain unclear. Rumination bolus, a proxy for rumen microbiota, combined with exhalomics (analysis of exhaled volatiles), offered a noninvasive approach to differentiate breed responses to CH4 mitigation strategies. We investigated whether differences in rumination bolus microbiota and exhaled VFA (eVFA) between BS and HF cows contribute to their responses to 3-NOP. Sixteen multiparous cows (8 BS, 8 HF) were studied in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of 3-NOP (0 or 60 mg/kg of DM) and Acacia mearnsii tannin extract (TAN; 0% or 3% of DM). Rumination bolus samples collected 6 h postfeeding during the fourth period of the experiment were sequenced for full-length 16S rRNA sequences (PacBio Revio platform) to assess bacterial diversity, while exhaled samples from all 4 periods were analyzed for VFA using secondary electrospray ionization-MS. Microbial community shifts were analyzed using Bray-Curtis, unweighted, and weighted unique fraction metric (UniFrac) distances. Spearman correlations were performed between genus-level information and eVFA, CH4, hydrogen (H2), carbon dioxide (CO2), DMI, and milk yield between breeds. Supplementation of 3-NOP induced a modest but consistent shift in microbial composition, whereas TAN effects were minimal and inconsistent. Breed-specific differences were evident: BS harbored more Prevotella and Rikenellaceae, and HF were enriched in Succinivibrionaceae and Acetitomaculum. Under 3-NOP, HF genera aligned more strongly with propionate-producing pathways and showed stronger negative correlations with CH4, and BS genera remained more associated with acetate and butyrate proportions. Correlations with feed intake and milk yield were generally weak and inconsistent across genera. Overall, our results indicate that HF cows are more responsive to 3-NOP, likely redirecting spared H2 toward propionate-producing bacteria, and BS are more resilient to H2 fluxes and consequently less responsive to 3-NOP. Findings from this pilot study highlight the importance of host-microbiome interactions in evaluating and implementing enteric CH4 mitigation strategies in dairy cattle.
This study assessed the agreement between manual and automatic body condition scoring systems, with a focus on evaluating 2 automated scoring systems by DeLaval (older and newer) for commercial dairy farms. Manual scoring was conducted by experienced assessors using a standardized protocol, and results were compared with data from automated systems. Manual scores showed strong consistency between assessors, supporting the reliability of the method when properly applied. Both automated systems correlated well with manual scores. However, the older system consistently overestimated scores, particularly in thinner cows, whereas the newer system demonstrated closer alignment with manual assessments under the present conditions, though it slightly underestimated early-lactation body condition loss. Despite some limitations in individual cow assessment, especially during early lactation, the newer system represents a potential advancement and both systems are suitable for group-level management. Further refinement is recommended to enhance its precision for individual animal-level monitoring and research applications.
This study evaluated the use of serum total solids (STS) to assess passive immunity in Holstein and Angus cross Holstein calves. The objectives of our study were to (1) determine whether STS and serum IgG differs between Holstein and Angus × Holstein (Angus X) newborn calves, (2) compare the relationship between STS and serum IgG in both breeds, and (3) determine whether the industry-recommended passive immunity STS cutpoint (>62 g/L) for predicting serum IgG concentration ≥25 g/L is appropriate for Angus X calves. This observational study was part of a wider clinical trial in which calves were randomized to colostrum IgG doses ranging from 200 to 350 g. Blood samples were taken from calves at 2 d of age, and the separated serum was tested for STS (g/L) using optical refractometry. The remaining serum was stored frozen at -20°C and tested 2 wk later for IgG concentration (g/L) using radial immunodiffusion. Multivariable linear regression models were used to compare serum IgG and STS between breeds, controlling for colostrum IgG dose and calf sex. Pearson correlation coefficient and linear regression models were used to compare correlations between serum IgG and STS by breed. Area under the curve (AUC) and diagnostic sensitivity (Se) and specificity (Sp) were used to measure the ability of STS to identify calves with serum IgG ≥25 g/L. The number of calves analyzed in the final dataset from each group were 272 Holstein and 119 Angus X. Although serum IgG was similar between breeds, Holstein calves had 3.1 g/L (95% CI: 1.7, 4.5) higher STS than Angus X calves. The AUC of STS for predicting IgG ≥25 g/L was the same for both breed groups (AUC = 0.86). A previously recommended cutpoint of 62 g/L STS had Se and Sp of 51% and 91%, respectively, when predicting serum IgG ≥25 g/L in Holsteins. We found that a STS cutpoint that was 3 g lower (59 g/L) in Angus X calves provided similar performance (Se 55%, Sp 94%). Although colostral IgG absorption is similar between breeds, the relationship between serum IgG and STS differs, likely due to Angus X calves having a lower concentration of non-IgG proteins in serum. Although we acknowledge that the sensitivity of these cutpoints is low, we believe that breed-specific thresholds may be necessary to predict a calf serum IgG ≥25 g/L for Angus X calves, compared with the >62 g/L recommendation proposed for Holsteins in the literature.
Accurate estimation of urine output is essential for assessing nutrient utilization, particularly for nutrients predominantly excreted through urine, such as minerals and protein-derived metabolites. An equation utilizing creatinine concentration and BW has been previously developed to estimate urinary volume (EUV) in lactating Holstein dairy cows, defined as EUV = [29 × BW (kg)]/[urinary creatinine (mg/L)]. Our objective was to evaluate whether this equation introduces bias when used for estimating urinary output in nonpregnant, nonlactating Holstein cows and to identify factors influencing its accuracy. For our study, we used 72 paired observations that included observed urinary volume (OUV) and urinary creatinine concentration. These observations were obtained from a prior research study that assessed the relative availability of various magnesium (Mg) sources using a duplicated 6 × 6 Latin square design, with cows (n = 12) grouped into squares based on lower (square 1) or higher (square 2) BW across 6 periods. Enrolled cows were of second parity (n = 8) and third or greater parity (n = 4), with BW ranging from 590 to 831 kg. To determine the agreement between EUV and OUV, we constructed 2 mixed-effects models. The first model evaluated slope bias (testing if the slope was significantly different from 1), whereas the second assessed mean bias (testing if the intercept was significantly different from 0) between EUV and mean-centered OUV. In our dataset, creatinine excretion per kilogram of BW ranged from 15.0 to 35.6 mg/kg BW with an average of 27.6 mg/kg BW. When assessing the agreement between OUV and EUV, we observed both slope and mean biases when applying the creatinine-based equation. Furthermore, there was a bias estimate across BW quartiles. Overall, 76.4% of observations fell within ±10% deviation range between EUV and OUV. These findings suggest that further research is needed to identify factors that can refine the creatinine and BW-based predictive equation specifically for nonpregnant, nonlactating Holstein dairy cows.
This experiment evaluated the effects of administering the maternal bovine appeasing substance (mBAS) at the time of artificial insemination (AI) on pregnancy per AI (P/AI) of Holstein cows under commercial dairy conditions. A total of 375 lactating Holstein dairy cows (178 primiparous and 197 multiparous cows) from 2 commercial dairy farms were enrolled. All cows were assigned to an ovulation synchronization + AI protocol when they reached 65 DIM. The protocol included 2 mg of estradiol benzoate + intravaginal progesterone-releasing device (DIB) on d -10, followed by 25 mg of dinoprost tromethamine on d -3, followed by 25 mg of dinoprost tromethamine + 1 mg of estradiol cypionate + 400 IU of equine chorionic gonadotropin + DIB removal and tail paint on d -2. On d 0 (24 h after tail paint application), cows with paint removed were classified as in estrus and inseminated. Cows with intact tail paint were considered not to be in estrus, administered 100 µg of GnRH, and inseminated 8 h later. At the time of AI, cows within farm and parity were randomly assigned to receive mBAS (Ferappease, FERA Diagnostics and Biologicals, College Station, TX; n = 197) or no treatment (CON, n = 178). The mBAS (10 mL) was applied topically to the nuchal skin area (5 mL) and above the muzzle (5 mL). Pregnancy status to AI was verified by detecting a viable embryo with transrectal ultrasonography 32 d after AI. Cows assigned to mBAS or CON had similar DIM at the time of AI, milk yield, and incidence of estrus during the synchronization protocol. Administering mBAS increased P/AI by 12.5 percentage points compared with CON cows (60.2% vs. 47.7%). Based on treatment differences in P/AI and an economic value of $200/pregnancy, mBAS administration yielded a return-on-investment of 833%. This calculation assumed mBAS cost of $3.00/cow, a herd of 1,000 cows in which mBAS yielded 125 more pregnancies, resulting in an economic benefit of $25,000 ($25,000/$3,000 = 8.33). The results of this experiment are novel and provide evidence that mBAS is effective in enhancing the reproductive performance of lactating dairy cows when applied during critical stress-sensitive periods such as AI.
This observational study with voluntary participation investigated drying-off practices and dry period-related udder health key performance indicators in 3 important dairy production regions in Germany (the north [NR], east [ER], and south [SR]). Data from DHI testing and information about drying-off practices were collected during a single herd visit between 2016 and 2019 from 253, 252, and 260 farms in NR, ER, and SR, respectively. Abrupt cessation of lactation was most common in NR and ER, but only practiced on about half of the farms in SR (NR: 79%, ER: 75%, SR: 56%). Blanket dry cow therapy (BDCT, the use of antibiotic agents for all cows) dominated in NR and ER (63% and 65%, respectively), whereas in SR, primarily selective dry cow therapy (SDCT, targeted use of antibiotic agents at drying-off for individual cows according to farm-specific criteria; 56%) or even no use of antibiotic dry cow therapy (20%) were adopted. The use of teat sealants (TSL) with or without the use of antibiotics was most common in ER (66%), followed by farms in NR (54%), and least common in SR (30%). The median new infection risk (using a SCC threshold of 100,000 cells/mL of milk) during the dry period (NIRD; cows with SCC ≤100,000 before dry period and SCC >100,000 at first test-day post dry period) in NR, ER, and SR was 24% (interquartile range: 13%-35%), 25% (18%-35%), and 24% (8%-37%), and the cure risk during the dry period (CRD; cows with SCC >100,000 before dry period and SCC ≤100,000 at first test-day post dry period) in NR, ER, and SR was 63% (51%-72%), 57% (47%-65%), and 60% (42%-75%), respectively. The NIRD and CRD varied greatly between farms, indicating improvement potential on many dairy farms.
This study was conducted to assess the effects of encapsulated algae oil (EAO) supplementation on the production of docosahexaenoic acid (DHA)-enriched milk in mid-lactation dairy cows. A total of 60 mid-lactation dairy cows were randomly assigned to 4 treatment groups, comprising the addition of EAO (DHA >17%) at 0, 60, 120, and 180 g/d per head (equivalent to 0, 10, 20, and 30 g/d DHA). The experiment lasted for 8 wk, with an additional 10-d prefeeding period. Compared with the control group, the ECM and fat content were increased in 10 g/d DHA group, but decreased with the 20 g/d and 30 g/d DHA levels. No significant treatment effect was observed on DMI and milk composition. The content of milk DHA exceeded 100 ppm (10 mg/100 mL) by the fifth week when 30 g/d DHA was administered. The conversion rate for all groups exceeded 10%, whereas the group supplemented with 10 g/d DHA exhibited the highest level. No significant differences were found in SFA or MUFA levels. In contrast, PUFA, including DHA, significantly increased with the EAO supplementation. In addition, compared with raw milk, the DHA content of pasteurized milk decreased by 8.39%, and UHT milk decreased by 25.64%. In summary, EAO supplements significantly increased the milk DHA content without influencing the overall milk performance of dairy cows.
The relationship between oxidative stress, inflammation, and productivity loss associated with heat stress has been documented in dairy cattle. Resveratrol, a naturally occurring plant-based polyphenolic compound, possesses antioxidant properties because of its chemical structure. We hypothesize that supplementing resveratrol would improve the antioxidant capacity and reduce heat stress-induced oxidative stress in lactating dairy cows. The objective of the study was to determine the effects of resveratrol supplementation on plasma markers of oxidative stress and their relation with productivity, respiratory rate (RR), and rectal temperature (RT) in heat-stressed dairy cows. The study was conducted during summer using 30 Holstein cows averaging (±SD) 127 ± 33 DIM, 48.9 ± 8.9 kg/d milk yield, and 2.1 ± 1.0 parity housed in a sand-bedded freestall barn at the University of Tennessee dairy farm. Following a 1-wk baseline period, cows were allocated to 1 of 2 treatment groups, control (CON; n = 15, TMR with no resveratrol) or resveratrol (RES; n = 15, TMR with 0.5 g resveratrol/cow per day) for 2 wk of adaptation period. During baseline and adaptation periods, fans and soakers enhanced cows' evaporative cooling. Following the adaptation period, fans and soakers were disabled, cows experienced natural summer heat stress, and treatments were imposed for 3 wk. Temperature and humidity loggers recorded weather variables in the barn. Rectal temperature and RR were recorded 3 times daily. Blood samples were collected once a week, and plasma was isolated to measure markers of oxidative stress. Data were analyzed using the MIXED procedure with repeated measurements in SAS. The effects of treatment, week, parity, and their interactions were considered fixed, and animal was considered a random effect. Baseline measurements were included in the statistical analysis as covariate if significant. A suitable covariance structure was used based on the lowest Akaike and Bayesian information criteria. Regression analysis determined the relations between milk yield and plasma total antioxidant capacity, and RT or RR with plasma total antioxidant capacity. Results showed that the ambient temperature and relative humidity ranged between 20°C and 30°C and 49%-84% during the treatment period. Compared with CON, the RES treatment increased plasma total antioxidant capacity up to 12% in parity 2 cows. The RES treatment did not affect plasma concentrations of superoxide dismutase and malondialdehyde but tended to reduce plasma pro-oxidant-antioxidant balance in wk 2 and 3. Regression analysis indicated that plasma total antioxidant capacity was positively related to milk yield in both RES (R2 = 0.13) and CON cows (R2 = 0.02). Specifically, a 1 mM increase in plasma total antioxidant capacity was associated with an 8.5 kg higher milk yield in RES cows compared with CON cows. Regression analysis indicated that RR was explained weakly by plasma total antioxidant capacity in CON cows only (R2 = 0.01). In conclusion, RES increased plasma total antioxidant capacity and mitigated oxidative stress and production loss in heat-stressed dairy cows. Resveratrol could be used as a feed additive to reduce the effect of heat stress on commercial dairy farms.
The occurrence of mycotoxins in ruminant feeds has been traditionally linked to corn silage, but alternative forages such as cereal straw, grass silages, sorghum, and legume hays may also contribute to exposure. We investigated the main regulated mycotoxins in 977 forage samples from Italian farms, including 642 silages (wheat, grasses, sorghum) and 335 hays (wheat straw, grasses, alfalfa). Samples were analyzed for deoxynivalenol, zearalenone (ZEN), and total fumonisins (FUM) using accredited methods. Noncorn forages were not exempt from contamination, showing variable prevalence and concentrations depending on forage type and botanical origin. Deoxynivalenol was the most prevalent, ZEN showed moderate prevalence with rising concentrations in recent years, and FUM occurred less frequently but with occasional and not significant high levels. These findings highlight the need for continuous monitoring of all forage types, suggesting that mycotoxin risk assessment in dairy diets should extend beyond corn silage.
Feeding spoiled silage with high yeast activity is commonly related to impaired lactation performance by dairy cows. However, rehydrated corn grain silage (RCGS) may be more prone to yeast proliferation and be greatly affected by high yeast populations. This experiment assessed the effects of increasing wild yeast counts on the nutrient composition, fermentation profile, and aerobic stability of RCGS at different storage lengths. Wild yeast was obtained after exposing high-moisture corn to an aerobic environment for 10 d. The experiment consisted of 4 treatments (theoretical concentration of 0 [only distilled water; CON], 5.3 [low yeast; LY], 6.3 [medium yeast; MY], and 7.3 [high yeast; HY] log cfu/g of RCGS) for either 30 or 90 d of storage in quadruplicate (used as blocking factor), for a total of 32 laboratory silos. Minimal changes in nutrient composition and aerobic stability were detected regardless of treatment and storage length. At 30 d, acetic acid and ethanol concentrations showed a positive linear relationship with increasing wild yeast count. Greater yeast count was observed in silage inoculated with wild yeast compared with CON, but no differences were detected among inoculated silage. The 7-h in vitro DM degradability linearly decreased with increasing wild yeast counts. At 90 d, total acid concentration was greater for HY compared with other treatments, with a positive quadratic relationship when increasing wild yeast count. Similarly, lactic acid concentration was greater for HY compared with other treatments, with a positive linear relationship when increasing wild yeast count. In addition, HY had greater ethanol concentration compared with other treatments, with a positive linear relationship when increasing wild yeast count. The 7-h in vitro DM degradability was quadratically related to wild yeast population. Overall, this study provides additional information regarding the nutrient composition, fermentation profile, and aerobic stability of RCGS with wild yeast inoculation. Moreover, high wild yeast populations can reduce in vitro DM degradability, which could potentially affect performance of dairy cows. Further research is warranted to identify wild yeast populations as their presence is dependent on their species and metabolism.
Video-based livestock monitoring offers a noninvasive, cost-effective, and scalable alternative to direct human monitoring, but also to commonly used collar or ear tag devices on farms. It enables simultaneous real-time observation of multiple animals while avoiding stress and injuries from physical devices. However, single-camera systems face challenges such as blind spots and limited individual tracking, especially in barns lacking corridor layouts. These limitations can be overcome using multi-camera, multi-cow tracking (MCMCT) systems that integrate deep learning and statistical techniques to enable continuous detection, identification, activity classification, and zone location of animals in the barn, under commercial conditions. This environment is characterized by high stocking density (in m2 per cow), occlusions, and variable lighting. In this study, a commercial MCMCT system was tested over 31 d (May 2025) on 3 Holstein dairy farms in western France. Herd size ranged from 70 to 250 lactating cows and used automatic milking systems (AMS), which allowed identification of all animals when milked. Individual detection performance of this MCMCT system was then validated compared with official AMS records. A dedicated hybrid confusion matrix framework was developed to jointly assess detection and identification errors in the sequential process, allowing precise calculation of recall, precision, and F1-scores at both stages. Overall, this MCMCT system achieved over 90% detection recall and 87% to 93% precision, successfully detecting continuously more than 9 out of 10 cows daily. Identification was more challenging, with recall varying from 69% to 78% and precision above 83%, resulting in F1-scores of 79% to 82%. The performance of detection varied significantly between day and night in 2 out of 3 farms (H1 and H2), with recall rates dropping to 76% at night and exceeding 94% during peak daylight, underscoring the impact of lighting and activity patterns. Activity classification and zone location were robust, with F1-scores exceeding 87%, demonstrating the system's capacity to provide practical insights for herd management such as monitoring individual behaviors, identifying high-density zones around resources, and supporting daily management decisions. This work confirms the system's practical viability as a scalable, noninvasive monitoring solution effective under commercial farm complexities such as crowding, occlusion, and lighting variability. The integration of day-night performance analysis and the hybrid confusion matrix provide a rigorous and transparent framework for assessing system reliability, critical for deploying precision livestock farming technologies. Identification performance decreased under overcrowded conditions. Overcrowding is defined here as a surface area of less than 9 m2 per cow or less than one cubicle per cow, as recommended by the EFSA Panel on Animal Health and Animal Welfare in 2023. The system demonstrates significant potential to support and enhance herd management, early disease detection, and animal welfare monitoring.
Artificial intelligence is increasingly applied in livestock farming and offers valuable tools for monitoring animal health and welfare. Among these, facial expressions have emerged as informative indicators of well-being in animals. In this context, the main objective of this study was to evaluate the accuracy of pose estimation models for extracting facial features in North American Holstein calves. Three YOLOv8-based models were trained using 10, 16, and 30 facial keypoints, and their performance was evaluated using training metrics (loss, precision, recall, F1 score, training time, and number of epochs) and keypoint accuracy measures (object keypoint similarity, average precision, average recall). The 10-keypoint model outperformed the others, requiring less training time, achieving lower loss, and yielding the highest prediction accuracy. This model enabled reliable extraction of facial phenotypes, including nostril distance, eye opening, and ear angles and movements. These findings demonstrate the potential of pose estimation models for automated phenotyping and welfare monitoring in dairy calves.
A global comparison of dairy cow breeding objectives provides valuable insight into areas of convergence and divergence, helping identify populations with compatible breeding goals for sourcing germplasm to strengthen domestic genetic improvement programs. The objective of this study was primarily to compare the rankings of Holstein-Friesian artificial insemination sires across countries on the total merit index value of each country. The study also examined how different countries present estimates of genetic merit and how frequently they update their base populations; Denmark, Finland, and Sweden (DFS) were treated as a single group. The partial correlation among 22 indexes (i.e., 21 national indexes plus the Holstein Association USA Total Performance Index) was estimated for 49,450 Holstein(-Friesian) sires born post-2000 with a reliability >70%, after adjustment for genetic trends. The partial correlations among the ranking of sires on different indexes varied from 0.24 to 0.87 with 41% of the pairwise correlations being stronger than 0.70 but just 11% being stronger than 0.80. Notably, indexes designed for indoor confinement-based systems had, on average, weaker correlations with grazing-focused indexes from Ireland and New Zealand (0.48 to 0.50). Stronger average correlations (0.69) were observed among the ranking of sires on confinement-based indexes; the correlation between the Irish Economic Breeding Index and New Zealand Breeding Worth was 0.56. When limited to just the milk production components of the different indexes, the partial correlations among the ranking of sires on subindexes were, on average, 0.78, varying from 0.29 (Uruguay with Poland) to 0.96 (Japan with Spain). Countries differ in their approach to trait weighting. Across the 21 countries examined in this study, 38% derived the weights assigned to traits solely from economic models or functions, whereas an additional 29% of the countries adopted only a desired-gains approach. The remainder of countries adopted a hybrid strategy, applying economic values to certain traits, typically the production traits, while using desired gains for others (e.g., the Netherlands, DFS). In some cases, initial weights were derived from economic principles but subsequently adjusted to achieve specific desired gains (e.g., Canada, Australia, Uruguay). Of the 21 milk production subindexes compared, 8 had a negative weight on milk yield (i.e., Canada, DFS, United Kingdom, New Zealand, Australia, Belgium, Ireland, Uruguay), 4 had a positive value (i.e., United States, Poland, Spain, South Africa), whereas Germany, the Netherlands, Japan, France, Slovenia, Italy, Israel, Switzerland, and Hungary did not consider milk yield in their total merit indexes. With the exception of Ireland, United Kingdom, United States, Israel, and Uruguay who presented genetic evaluations of individual animals as PTA, genetic evaluations of milk production traits are presented as EBVs by all other countries. Of the 21 countries, 10% update their genetic evaluation base population more than once per year, 38% update it annually, 38% update it every 5 yr, and the remaining 14% update it periodically. Health traits are increasingly being considered for inclusion in future breeding objectives as are traits associated with both environmental impact and feed efficiency. The findings underscore how economic, biological, genetic, and policy factors shape national breeding objectives, helping interpret international differences in genetic trends and performance outcomes.
Dairy cows with full cow-calf contact can nurse their calves and perform maternal behaviors without hindrance. Owing to the unrestricted suckling, the total milk production of the suckled cows (i.e., machine milk yield [MMY] and milk consumed by the calf) is unknown, albeit required for performance testing and sustainability analyses of prolonged cow-calf contact. This study aimed to estimate the daily milk production of dairy cows with full cow-calf contact spanning the whole day using 2 methods. First, individual milk production was estimated using the daily energy intake during the preweaning suckling period and the ratio of MMY to the previous day's energy intake, calculated for the 8-wk postsuckling period. Second, individual milk production was estimated using the daily MMY during the suckling period and adding the estimated calf milk consumption based on their body weight, growth, and energy intake from concentrates. This was done for conventionally managed cows with no contact with their calves beyond 13.5 h after birth (NC; n = 20) and for cows with full contact with their calves until gradual weaning at 13.0 ± 1.1 wk of age (FC; n = 18). Using the first method based on energy intake of the cow, milk production of NC cows was estimated at 33.33 ± 1.40 kg/d and their milk yield to the automatic milking unit averaged 37.73 ± 1.40 kg/d during the first 12 wk of lactation. This discrepancy might be because cows likely experienced a negative energy balance during the preweaning period, which was not accounted for in the estimation. For FC cows, average milk production was estimated at 35.30 ± 1.40 kg/d and their milk yield to the milking unit averaged 24.74 ± 1.60 kg/d during the suckling period of the first 12 wk of lactation. Using the second method based on the estimated milk consumption of FC calves (14.91 ± 2.9 kg/d; mean ± SD), milk production of FC cows during the suckling period was estimated at 37.94 ± 1.80 kg/d. In conclusion, both methods evaluated could estimate milk production of suckled FC cows. In the first method, milk production was underestimated when using ME intake and milk yield during the nonsuckling period, possibly due to not accounting for body reserve mobilization. In the second method, milk production of suckled cows estimated using calf growth aligned with the recorded MMY of nonsuckled cows. The ∼15 kg/d estimated milk consumption of FC calves during the first 13 wk of life corresponded to the recorded milk yield difference between FC and NC cows. Methods evaluated in this study can be applied for performance testing and sustainability analyses of cow-calf contact systems.