Predictive models for disease detection in group-housed preweaning dairy calves using data collected from automated milk feeders.

In the United States, dairy calves are typically housed individually due to the perception of reduced risk of spreading infectious diseases between calves and the ability to monitor health on an individual calf basis. However, automated milk feeders (AMF) can provide individual monitoring of group-housed calves while allowing them to express more natural feeding behaviors and interact with each other. Research has shown that feeding behaviors recorded by AMF can be a helpful screening tool for detecting disease in dairy calves. Altogether, there is an opportunity to use the data from AMF to create a more robust and efficient model to predict disease, reducing the need for visual observation. Therefore, the objective of this observational study was to predict disease in preweaning dairy calves using AMF feeding behavior data and machine learning (ML) algorithms. This study was conducted on a dairy farm located in the Upper Midwest United States and visited weekly from July 2018 to May 2019. During farm visits, AMF data and calves' treatment records were collected, and calves were visually health-scored for attitude, ear position, ocular discharge, nasal discharge, hide dirtiness, and cough score. The final datasets used for the analyses consisted of 740 and 741 calves, with 1,007 (healthy = 594 and sick = 413) and 1,044 (healthy = 560 and sick = 484) observations (health events) for Data 1 and Data 2, respectively. Data 1 included only the weekly calf health scores observed by research personnel, whereas Data 2 included primarily daily calf treatment records by farm staff in addition to weekly health scores. Calf visit-level feeding behaviors from AMF data included milk intake (mL/d), drinking speed (mL/min), visit duration (min), rewarded (with milk being offered) and unrewarded (without milk) visits (number per d), and the interval between visits (min). Three approaches were used to predict health status: generalized linear model, random forest, and gradient boosting machine. A total of 16 models were built using different combinations of behavior parameters, including the number of rewarded visits, number of unrewarded visits, visit duration, the interval between visits, intake, intake divided by rewarded visits, drinking speed, and drinking speed divided by rewarded visits, and also calf age at the sick day as predictor variables. Of all algorithms, random forest and gradient boosting had the best performance predicting the health status of dairy calves. The results indicated that weekly health scores were not enough to predict calf health status. However, daily treatment records and AMF data were sufficient for creating predictive algorithms (e.g., F1-scores of 0.775 and 0.784 for random forest and gradient boosting, Data 2). This study suggests that ML was effective in determining the specific visit-level feeding behaviors that can be used to predict disease in group-housed preweaning dairy calves. Implementing these ML algorithms could reduce the need for visual calf observation on farms, minimizing labor time and improving calf health.

Developmental adaptations of γδ T cells and B cells in blood and intestinal mucosa from birth until weaning in Holstein bull calves.

This study aimed to characterize the development of systemic and colon tissue resident B and γδ T cells in newborn calves from birth until weaning. At birth, calves have limited capacity to initiate immune responses, and the immune system gradually matures over time. Gamma delta (γδ) T cells are an important lymphocyte subset in neonatal calves that confer protection and promote immune tolerance. A total of 36 newborn calves were enrolled in a longitudinal study to characterize how systemic and colon tissue resident B and γδ T cells develop from birth until weaning. Blood and colon biopsy samples were collected on d 2, 28, and 42 to determine the proportions of various B and γδ T cell subsets by flow cytometry. We classified γδ T cells into different functional subsets according to the level of expression intensity of the coreceptors WC1.1 (effector function) and WC1.2 (regulatory function). Furthermore, naive B cells were classified based on the expression IgM receptor, and activation state was determined based on expression of CD21 and CD32, 2 receptors with opposing signals involved in B cell activation in early life. Additional colon biopsy samples were used for 16S sequencing, and microbial diversity data are reported. At birth, γδ T cells were the most abundant lymphocyte population in blood, accounting for 58.5% of the lymphocyte pool, after which the proportions of these cells declined to 38.2% after weaning. The proportion of γδ T cells expressing WC1.1 decreased by 50% from d 2 to d 28, whereas no change was observed in the expression of WC1.2. In the colon, there was a 50% increase of γδ T cells after weaning and the proportion of WC1.2+ γδ T cells doubled from d 28 to 42. The proportion of IgM+ B lymphocytes in blood increased from 23.6% at birth to 30% after weaning, were the proportion of B cells expressing CD21 increased by 25%, while the proportion of B cells expressing CD32 decreased by 30%. While no changes were observed for the overall proportion of IgM+ B lymphocytes in the colon, there was a 6-fold increase in the proportion of CD21+ B cells from pre- (d 28) to postweaning (d 42). Microbial diversity increased from d 2 of life to 28 and declined abruptly after weaning. The reduction in microbial diversity during weaning was negatively correlated with the increase in all γδ T cell subsets and CD21+ B cells. These data suggest that developmental adaptations after birth coordinate expansion of γδ T cells to provide early systemic protection, as well as to steer immune tolerance, while B cells mature over time. Additionally, the increase of colonic γδ T cells on d 42 suggests a protective role of these cells during weaning.

Association between adenosine triphosphate luminometry of feeding equipment and environmental and health parameters of preweaning calves on dairy farms.

The objective of this study was to examine the influence of different environmental factors on ATP luminometry measurements of feeding equipment and to investigate associations with health of preweaning calves and the levels of ATP identified through luminometry. On 50 commercial dairy farms in Quebec, Canada, ATP luminometry measurements (in relative light units, RLU) were obtained using the direct swabbing technique with Hygiena UltraSnap swabs and a liquid rinsing technique with the same swab for automatic milk feeders (AMF), bottles, buckets, esophageal tube feeders (ET), milk replacer, nipples, and water. During this visit, environmental factors (including temperature, air draft, humidity, ammonia, and bacterial count) were collected, and a clinical examination (including respiratory score and fecal score) was performed for all preweaning calves present at the farm. This process was repeated 4 times in a year, leading to collection of luminometer results, environmental parameters, and overall health of calves for each season per farm. Overall, a difference in luminometer results was seen between the different periods sampled for all feeding equipment (except the ET), milk replacer, and water, showing higher RLU values in spring and summer and lower values in autumn and winter. When comparing RLU measurements with environmental factors, only a low to negligible correlation could be found. When feeding equipment was classified as not contaminated or contaminated based on previously described cutoff values, a good agreement within a farm for the different seasons was noticed only for nipples (Gwet's agreement AC1 = 0.64), with a poor to moderate agreement for other feeding equipment. Regarding the different models of nipples, Peach Teat nipples showed higher RLU values compared with Merrick's nipples. An association was seen between the proportion of preweaning calves suffering from diarrhea on the farm and the contamination of AMF based on ATP luminometry (logistic regression estimate = 0.52). For other feeding equipment, milk replacer, and water, no significant associations were found. This study showed that ATP luminometry measurements of feeding equipment from preweaning calves are susceptible to seasonality and type of nipple. Thus, these factors should be taken into consideration when interpreting results. Additionally, an association could be made between diarrhea in preweaning calves and the contamination of AMF based on ATP luminometry, showing the potential clinical importance of this on-farm hygiene assessment tool.

Comparison and interobserver reliability between a visual analog scale and the Wisconsin Calf Health Scoring Chart for detection of respiratory disease in dairy calves.

Respiratory disease is an ongoing challenge for calves in the dairy sector with a relatively high prevalence and impact on welfare and economics. Applying scoring protocols for detecting respiratory disease requires that they are easily implemented, consistent between observers and fast to use in daily management. This study was conducted in one Danish dairy farm from September 2020 through January 2021. The study included 126 heifer calves enrolled in the age of 17 to 24 d. All calves were observed every second day for a period of 46 d. At each visit all calves were scored with a new visual analog scale (VAS) and the Wisconsin Calf Health Scoring Chart (WCHSC). We calculated agreement between the 2 scoring systems based on conditional probability to score higher or lower than a cutoff in the VAS compared with a specified cutoff in WCHSC used as reference test. A generalized mixed effects regression model was developed to estimate the prevalence of respiratory disease and the overall agreement between the 2 scoring systems. The overall agreement between the VAS and WCHSC was 89.6%. The second part of the study assessed interobserver reliability between 2 experienced observers and between an experienced observer and veterinary students. The interobserver reliability was calculated by intraclass correlation coefficient and was 0.58 between experienced observers and was 0.34 between an experienced observer and veterinary students indicating a moderate to poor reliability between the observers. It was possible to use VAS as an alternative clinical scoring method, which primarily focuses on the general condition of the individual calf rather than specific categories of clinical signs. Our study set up lacked a comparison to other diagnostic tools i.e., thoracic ultrasound to confirm the findings which should be considered in future studies when exploring VAS as a screening tool for detection of respiratory disease in dairy calves.

Injection of antioxidant trace minerals/vitamins into peripartum crossbred cows improves the nutritional and immunological properties of colostrum/milk and the health of their calves under heat stress conditions.

Multimineral and vitamin injections can provide better nutrient availability at the cellular level, which is essential for mitigating transition period stress and improving the wellbeing and productivity of dairy cows. The present study was conducted to assess the colostrum quality and calf health after intramuscular injection of multi-minerals (MM) and multi-vitamins (MV) to peripartum cows during winter (THI = 58 to 66) and summer (THI = 78 to 82) months. In each season, twenty-four pregnant crossbred Karan Fries cows were grouped into four, each consisting of six cows. Group I, referred to as the Control, received solely the basal diet, without any additional supplements. Groups II, III, and IV were administered additional MM (T1), MV (T2), and a combined MM and MV (T3) along with their basal diet, starting 30 days before calving and continuing for 30 days after calving. Blood samples were collected from the calves, while colostrum/milk samples were obtained from the cows on days 1, 3, 7, and 15 after calving. The somatic cell counts (SCC) in the milk were determined using a cell counter. Cortisol, IgG, IGF1 and total immunoglobulins (TIG) in whey and plasma from cow colostrum/milk or calf blood samples were estimated by ELISA. Cows that calved in the summer exhibited notably reduced levels (P < 0.05) of IgG, milk, and plasma IGF1, along with lower calf body weights, in comparison to those calving in the winter season. Furthermore, the summer months saw significant increases (P < 0.05) in plasma and milk cortisol levels, as well as total somatic cell counts (SCC) in both colostrum and milk samples. Maximum beneficial effect was observed in T3 group. Results indicate that injections to peripartum cows could be an important strategy for improving colostrum quality and calf health during the summer seasons.

Effects of weaning strategies on health, hematology, and productivity in Holstein dairy calves.

Weaning strategies in dairy calves vary considerably, though the effect on animal health is unclear. This study examined the effects of calf weaning age (6 vs. 8 wk) and pace (abrupt vs. gradual) on performance, blood, and health parameters in dairy calves. The experiment consisted of a 2 × 2 factorial arrangement of treatments, where the factors included weaning age (early vs. late) and weaning pace (abrupt vs. gradual). Holstein calves (n = 72), blocked by sex and birth weight, were randomly assigned to one of 4 treatments (n = 18 per treatment): early-abrupt (EA), early-gradual (EG), late-abrupt (LA), and late-gradual (LG). Milk replacer (24% crude protein, 17% fat; up to 1,200 g/d) was fed twice daily; water, calf starter (18% crude protein), and chopped alfalfa hay were fed ad libitum. Daily intakes of milk replacer, calf starter, and forage were recorded from birth until end of weaning. Body weight, selected health measures, blood hematology, and fecal scores were obtained 1 d preweaning and 1 d postweaning. Calves were orally bolused with a rumen pH logger for the last 3 d of the weaning transition and rumen pH was measured continuously. Data were analyzed with age, pace, age × pace interaction, birthweight, and sex as fixed effects, and starting date as a random effect. Greater age at weaning increased respiration, whereas gradual-weaned calves had lower respiration rate. Heart rate was lower in gradual than in abrupt weaned groups. Fecal score had a marginal increase in late-weaned groups and significantly increased in gradually weaned groups. No difference was detected in body core temperature by age, pace, or interaction. During the weaning transition, average daily gain was lower in LA than EA and gradually weaned groups had an increased average daily gain. Change in grain intake, but not forage intake, was greater in gradually weaned groups. Mean rumen pH marginally increased from EG to LG and from LA to LG. No difference was detected among treatments in red or white blood cell counts, and hemoglobin. Procalcitonin was marginally highest in the LA group, while blood hematocrit increased in abruptly weaned groups. Overall, calf health is affected by both age and pace of weaning, though the health parameters affected by age and pace differ.

Comparison of calf morbidity, mortality, and future performance across categories of passive immunity: A retrospective cohort study in a dairy herd.

Four categories of transfer of passive immunity (TPI) were recently proposed in response to the widespread high preweaning morbidity and mortality risks in calves with adequate TPI when a dichotomous classification was used. Hitherto, however, the risks of preweaning morbidity and mortality and future performance among these TPI categories have not been compared. Thus, the objective of this retrospective cohort study was to compare dairy calf morbidity, mortality, growth until weaning, and reproductive efficiency until first calving among the categories of poor (<5.1 g/dL total protein), fair (5.1-5.7 g/dL), good (5.8-6.1 g/dL), and excellent (>6.2 g/dL) TPI. For this, the records from 4,336 dairy calves (2,272 female, 2,064 male) born January 2014 to April 2017 on a commercial dairy farm in Michigan were analyzed. These calves had been randomly selected for weekly serum total protein determination on calves 2 to 7 d old. Data from both sexes were used to evaluate preweaning health and mortality, whereas only the female's data were used to investigate average daily gain (ADG), reproductive performance, and first-lactation milk yield. For each calf, data regarding disease status, growth, and reproductive parameters were obtained from the farm's software database. Associations of TPI categories with disease events (diarrhea or pneumonia), reproduction indices (age at first insemination, successful insemination, and calving, and number of inseminations), first-lactation milk yield and ADG at weaning were evaluated by survival analysis and mixed models. Compared with calves with excellent TPI, calves in the inferior TPI categories showed increased risk of diarrhea: poor [hazard ratio (HR) = 1.49; 95% CI: 1.22-1.82], fair (HR = 1.32; 95% CI: 1.16-1.51), good (HR = 1.14; 95% CI: 1.02-1.29). However, the risk of pneumonia differed only between the calves in the poor and excellent TPI groups (HR = 1.39; 95% CI: 1.05-1.84). The preweaning mortality risk was also higher in calves with poor TPI (HR = 4.29; 95% CI: 1.98-9.27) compared with excellent TPI. However, mortality risks were not statistically different between calves with fair or good TPI and those with excellent TPI. Similarly, calves with poor TPI had a 64, 55, and 24% lower risk of reaching first insemination, successful insemination, or first calving, respectively. However, there were no differences in ADG, number of inseminations, or first-lactation 305-d mature equivalent milk production across TPI groups. Our results confirm the positive effects of optimal TPI in calf preweaning health and postweaning reproductive efficiency. The 4 proposed categories of TPI can assist in decreasing the incidence of diseases that occur in the first weeks of life (i.e., diarrhea), but their effect on other diseases or future performance might be more limited. Although conducted in one herd, this study can be used to illustrate the effect of TPI on future calf performance.

Standardization and validation of ATP luminometry as a diagnostic tool to assess the cleanliness of feeding equipment in preweaning calves.

The objective of this cross-sectional study was to standardize a reliable and repeatable swabbing technique using ATP luminometry (light emission proportional to the amount of ATP with result provided in relative light units [RLU]) to describe the cleanliness of various feeding equipment used for preweaning calves in dairy farms. A total of 7 Québec commercial dairy herds were selected conveniently. Following visual hygiene scoring, the cleanliness of every available piece of feeding equipment was assessed using direct surface swabbing for buckets and nipples with Hygiena UltraSnap swabs. A liquid rinsing technique was used for esophageal feeders, bottles, and automatic milk feeders (AMF) with UltraSnap, AquaSnap, and MicroSnap swabs. To validate direct swabbing technique of buckets, a stage within and between operators was realized, as well as a conventional bacterial culture. A total of 519 swab samples were obtained from 201 pieces of equipment. The median (interquartile range) contamination in RLU for a bottle, esophageal feeder, AMF, bucket and nipple was 2 (1;6), 2 (0;12), 52 (19;269), 886 (128;7,230) and 899 (142;6,928), respectively. The direct swabbing technique, which consists in swabbing directly the surface of an equipment, showed excellent correlation for intrarater reliability (intraclass correlation (ICC) = 0.93; 95% CI: 0.88-0.96). The interoperator (2 sessions with 3 different operators) reliability also showed high correlation (ICC = 0.88; 95% CI: 0.78-0.94 for the first session, and ICC = 0.89; 95% CI: 0.79-0.95 for the second session). Luminometer values were positively associated with the visual score of esophageal feeders, AMF and buckets. A positive correlation between bacterial culture and direct swabbing of buckets was also found for the UltraSnap (rs = 0.653; 95% CI: 0.283-0.873; P = 0.0003) and MicroSnap (rs = 0.569, 95% CI: 0.309-0.765; P = 0.002). This study describes a standardized and practical on-farm swabbing technique for assessing the hygienic status of feeding equipment by luminometry, which can be integrated in the investigation of preweaning dairy calves problems.

Health indicators in surplus calves at the time of arrival at auction markets: Associations with distance from farms of origin in Québec, Canada.

This study evaluated the associations between estimated distance from farms' locations to auction markets, and health indicators of surplus dairy calves sold during summer 2019 and winter 2020 in Québec, Canada. A total of 3,610 animals from 1,331 different farms were used in this cross-sectional cohort study. Geographic coordinates (latitude and longitude) were obtained for each farm and the 2 participating livestock auction markets. Calves' abnormal physical signs (APS) were noted upon arrival at the auction market as they were examined by trained research staff. The haversine distance between the farm and the auction market was evaluated using geographic coordinates and categorized. Generalized linear mixed models were used for statistical analyses. The main APS observed were ocular discharge (34.9%), abnormal hide cleanliness (21.2%), swollen navel (17.2%), dehydration score 1 (at least one of the 2 following clinical signs: persistent skin tent or sunken eye, 12.9%), and dehydration score 2 (both clinical signs mentioned above, 6.5%). Calves from farms located at greater distances from the auction markets (≥110 km) had a higher risk ratio [RR = 1.08; 95% confidence internal (CI) = 1.03, 1.13] for dehydration than those from lesser distances (0-25 km). During the summertime, a RR of 1.18 (95% CI = 1.15, 1.22) was observed for dehydration compared with wintertime. A 2-way interaction between estimated distance and season showed a higher prevalence of ocular discharge for calves from farms at distances greater than or equal to 110 km during the summer (RR = 1.11; 95% CI: 1.04, 1.20) than for calves from farms located at lesser distances (0-25 km). These results demonstrate that calves from farms located at greater distances from the auction markets had more APS, mainly during the summer. A better understanding of the transport conditions and interaction with management at the farm of origin is determinant to mitigate the impact of the journey on surplus calf health.

Invited review: Bovine neonatal morbidity and mortality-Causes, risk factors, incidences, sequelae and prevention.

The neonatal period may be defined as the first month of the calf's life; it may be considered part of the fourth trimester. It is the most hazardous due to the immaturity of the neonate's immune system and the environmental challenge from infections, the main causes of both bovine neonatal morbidity and mortality. The five most common morbidities causing mortality in neonatal calves are, in descending order, gastrointestinal infections, respiratory infections, abomasal disorders, umbilical infections and developmental abnormalities. This review describes the aetiology, incidence, risk factors and sequelae of these common morbidities and highlights current preventive strategies both at farm and national levels.

Use of ATP luminometry to assess the cleanliness of equipment used to collect and feed colostrum on dairy farms.

The objective of this observational cross-sectional study was to describe the cleanliness of various equipment used for colostrum harvest and calf feeding procedures on dairy farms in Québec, Canada. The study was performed on 42 commercial dairy herds also enrolled in another study aiming to determine the transfer of passive immunity over a 14-mo period. Information on colostrum quality (using Brix value) and cleanliness (total aerobic and total coliform count) were recorded as well as various practices focused on colostrum-feeding equipment and preweaning period using a standard questionnaire. During the study period, colostrum and milk-feeding equipment cleanliness was assessed using direct surface swabbing with Hygiena Ultrasnap swabs. A total of 155 swab samples were obtained from 6 pieces of equipment. Adenosine triphosphate collected from the swabbed surface reacts with the luciferase solution present in the swab by bioluminescence, which is proportional to the quantity of ATP present and quantified as relative light units (RLU). The description of feed equipment cleanliness (defined as the maximal RLU found for a specific herd, dichotomized as <1,000 RLU vs. ≥1,000 RLU) was compared with the herds' descriptive characteristics, focusing on the first 2 components of a multiple correspondence analysis. The median (range) RLU for buckets used for colostrum harvest, bucket or bottle used for feeding, tube feeders, milking colostrum line, and internal surface of the nipples were 41 RLU (3-1,625 RLU), 78 RLU (<1-3,765 RLU), 29 RLU (<1-2,177 RLU), 83 RLU (<1-9,968 RLU), and 1,101 RLU (2-9,546 RLU), respectively. The first 2 components of multiple correspondence analysis explained 24.7% of data variances and were related to the farms' hygiene and health (13.0%) and feeding practices (11.7% of data variance). The maximal dichotomized luminometry value (<1,000 RLU or ≥1,000 RLU) was associated with hygiene and health dimension. This study gave promising results concerning the potential application of ATP luminometry for calf rearing practices assessment.

Effects of feeding Saccharomyces cerevisiae fermentation products on the health of Holstein dairy calves following a lipopolysaccharide challenge.

Before weaning, dairy calves are at high risk for illness, especially respiratory and digestive diseases, which reduces average daily gain, age at first calving, and first-lactation milk production. Although these illnesses are commonly treated with antibiotics, efforts are being made to reduce antibiotic use, due to concerns about antibiotic-resistant bacteria. The objective was to evaluate the effects of Saccharomyces cerevisiae fermentation products (SCFP) on the immune status of calves, following a lipopolysaccharide (LPS) challenge administered just before weaning. Thirty Holstein bull calves were blocked based on initial body weight and then assigned to 1 of 2 study treatments. The control group (CON) was fed a 24% crude protein:17% fat milk replacer (MR) and calf starter with no SCFP added. The SCFP treatment was fed the same 24% crude protein:17% fat MR with 1 g/d of SmartCare (Diamond V) and calf starter with 0.8% NutriTek (Diamond V). SmartCare and NutriTek are both produced from anaerobic fermentation of S. cerevisiae. Calves were offered 2.84 L (12.5% solids) of MR twice daily at 0630 and 1630 h through d 51; from d 52 to 56, calves were fed MR once daily at 0630 h; and calves were weaned on d 57. Calves also received ad libitum access to a texturized calf starter and water. On d 50, a subset of calves (n = 20, 10 calves per treatment) were enrolled in an LPS challenge. At -1.5, -0.5, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, and 24 h relative to dosing with LPS, 20 mL of blood was collected, and rectal temperature and respiration rate were measured for each calf. Blood serum samples were analyzed for interleukin 6, TNF-α (tumor necrosis factor-α), interferon-gamma, haptoglobin, serum amyloid-A, fibrinogen, nonesterified fatty acid, cortisol, and glucose. This study observed increased concentrations of TNF-α at 1 h and 1.5 h and glucose at 0.5 h after dosing with LPS in SCFP calves compared with CON. Calves supplemented with SCFP also had an increase in respiration rate 0.5 h after dosing with LPS and reduced feed intake the day of the challenge compared with CON calves. These results suggest that dairy calves supplemented with SCFP exhibit an increased acute immune response, as observed by increased TNF-α, glucose, and respiration rate immediately after dosing with LPS, compared with CON calves.

Improving growth rates in preweaning calves on dairy farms: A randomized controlled trial.

Previous research has identified key factors associated with improved average daily gain (ADG) in preweaning dairy calves and these factors have been combined to create a web app-based calf health plan (www.nottingham.ac.uk/herdhealthtoolkit). A randomized controlled trial was conducted to determine the effect of implementing this evidence-based calf health plan on both productivity and health outcomes for calves reared on British dairy farms. Sixty dairy farms were randomized by location (North, South, and Midlands) to either receive the plan at the beginning (INT) or after the end of the trial (CON) and recorded birth and weaning weights by weigh tape, and cases of morbidity and mortality. Calf records were returned for 3,593 calves from 45 farms (21 CON, 24 INT), with 1,760 calves from 43 farms having 2 weights recorded >40 d apart for ADG calculations, with 1,871 calves from 43 farms born >90 d before the end of the trial for morbidity and mortality calculations. Associations between both intervention group and the number of interventions in place with ADG were analyzed using linear regression models. Morbidity and mortality rates were analyzed using beta regression models. Mean ADG was 0.78 kg/d, ranging from 0.33 to 1.13 kg/d, with mean rates of 20.12% (0-96.55%), 16.40% (0-95.24%), and 4.28% (0-18.75%) for diarrhea, pneumonia, and mortality. The INT farms were undertaking a greater number of interventions (9.9) by the end of the trial than CON farms (7.6). Mean farm ADG was higher for calves on INT farms than CON farms for both male beef (MB, +0.22 kg/d) and dairy heifer (DH, +0.03 kg/d) calves. The MB calves on INT farms had significantly increased mean ADG (0.12 kg/d, 95% confidence interval: 0.02-0.22) compared with CON farms. No significant differences were observed between intervention groups for morbidity or mortality. Implementing one additional intervention from the plan, regardless of intervention group, was associated with improvements in mean ADG for DH calves of 0.01 kg/d (0.01, 0-0.03) and MB calves of 0.02 kg/d (0.00-0.04). Model predictions suggest that a farm with the highest number of interventions in place (15) compared with farms with the lowest number of interventions in place (4) would expect an improvement in growth rates from 0.65 to 0.81 kg/d for MB, from 0.73 to 0.88 kg/d for DH, a decrease in mortality rates from 10.9% to 2.8% in MB, and a decrease in diarrhea rates from 42.1% to 15.1% in DH. The calf health plan tested in this study represents a useful tool to aid veterinarians and farmers in the implementation of effective management interventions likely to improve the growth rates, health, and welfare of preweaning calves on dairy farms.

Replacing concentrates with a high-quality hay in the starter feed of dairy calves: II. Effects on the development of chewing and gut fermentation, and selected systemic health variables.

Early development of the rumen, rumination, and fermentation is highly important in dairy calves. Yet, common rearing practices with feeding of concentrate-rich starters may jeopardize them because of lacking physically effective fiber (peNDF). The main objective of this study was to establish the influence of the composition of the calf starter feed (only forage with 2 different qualities or concentrate-rich starter diet) on chewing behavior, rumen development, rumen and hindgut fermentation, and selected systemic health and stress variables of dairy calves. The experiment was carried out with 40 newborn Holstein-Friesian calves, randomly assigned to 4 different solid feed treatments: MQH = 100% medium-quality hay (9.4 MJ metabolizable energy, 149 g of crude protein, and 522 g of neutral detergent fiber/kg of dry matter); HQH = 100% high-quality hay (11.2 MJ of metabolizable energy, 210 g of crude protein, 455 g of neutral detergent fiber/kg of dry matter); MQH+C = 30% MQH + 70% starter concentrate; HQH+C = 30% HQH + 70% starter concentrate). All calves were up to 14 wk in the trial and received acidified whole milk ad libitum in the first 4 wk of life, thereafter in reduced quantity until weaning on 12 wk of age. Water and the solid feed treatments were available ad libitum throughout the trial. Chewing activity was measured in wk 4, 6, 10, and 12 using RumiWatch halters. Until wk 3, rumen fluid, feces and blood were sampled weekly, thereafter every 2 wk. Rumen mucosal thickness (RMT) was measured on the same days with rumen fluid samples. Data showed that calves fed the HQH diet consumed more peNDF and this was associated with longer rumination time (591 min/d) and more ruminating boli (709 boli/d) than calves fed concentrate-rich diets (MQH+C: 430 min/d, 518 boli/d; HQH+C: 430 min/d, 541 boli/d), whereas the MQH group was intermediate (539 min/d, 644 boli/d). Ruminal and fecal pH were higher in calves fed only hay (especially MQH) compared with calves with concentrate supplementation. In both hay-fed groups, ruminal and fecal short-chain fatty acids were shifted toward acetate, whereas only the HQH diet increased the butyrate proportion in the ruminal short-chain fatty acids profile. Ruminal ammonia concentration was at a high level only in the first 3 wk and decreased thereafter. Feeding HQH tended to increase ruminal ammonia, likely because of its high crude protein content and ruminal degradability as well as lower assimilation from rumen microbes. The RMT similarly, though nonlinearly, increased in all groups over the course of the experiment. When using RMT as an indicator of rumen development in dairy calves in the practice, our data suggest an RMT of 1.7 mm and >2 mm at wk 5 and 10 of life, respectively. Feeding did not affect the blood levels of aspartate aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase, and cortisol. In conclusion, feeding high-quality hay, instead of concentrate-rich starter feeds, resulted in improved rumination and ruminal fermentation profile, without affecting ruminal pH and systemic and stress health variables.

Effects of supplementation with Saccharomyces cerevisiae products on dairy calves: A meta-analysis.

Saccharomyces cerevisiae products (SCP) have the potential to promote the growth and development of the gastrointestinal tract and immunity in young livestock animals. However, the effects of SCP supplementation on calves are inconsistent among the reported studies in the literature. Hence, we performed a meta-analysis to comprehensively assess the effects of SCP on the growth performance, ruminal fermentation parameters, nutrients digestibility, ruminal histological morphology, serum immune response, and fecal pathogen colony counts in calves. We searched the Web of Science, ScienceDirect, PubMed, and China National Knowledge Infrastructure for relevant studies published up to October 1, 2021. After screening against a set of criteria, the data of 36 studies were included in our meta-analysis (2,126 calves in total). We evaluated the quality of the data using sensitivity analysis and assessed publication bias. Our meta-analysis revealed several important findings. First, SCP supplementation increased the ruminal short-chain fatty acid concentration, ruminal papilla height, and fiber digestibility, pointing toward stimulation of the development of the rumen in calves. Second, SCP supplementation increased the serum concentrations of total protein, IgA, and IgG but decreased fecal pathogen colony counts, suggesting that SCP could help calves to promote immunity (especially maintaining circulating concentrations of immunoglobulins in preweaning calves) and resistance to pathogens. Third, a subgroup analysis between preweaning and postweaning calves showed that SCP increased average daily gain and dry matter intake preweaning but not postweaning, suggesting that SCP is better supplemented to preweaning calves to achieve the best results. Forth, based on the dose-response curve, 24 to 25 g/d might be the optimal dose range of SCP supplementation (into starter feed) preweaning to achieve the best overall effect, meanwhile, we need more studies to improve the consistency and accuracy of the dose-response curve prediction. Overall, SCP supplementation improved growth performance, rumen development, and immunocompetence in calves, particularly in preweaning calves.

Genetic parameters of calf morbidity and stayability for US organic Holstein calves.

The objectives of this study were to estimate genetic parameters of calf health in organic US Holstein calves. Calves were born on farms across the United States from 2006 to 2019. Three calf health traits were evaluated in the study: calf respiratory disease until 365 d of age, calf scours until 60 d of age, and heifer stayability until 365 d of age. For respiratory disease and scours, animals were assigned a phenotype of 0 if they were healthy and a phenotype of 1 if they were diseased. For stayability, animals were assigned a phenotype of 0 if they were removed from the herd by 365 d of age and 1 if they remained in the herd at 365 d of age. Genetic parameters were estimated from threshold models that included the fixed effects of mean, year-season of birth, and dam age (respiratory disease and scours only) as well as the random effects of herd-year of birth and additive genetics. Heritability estimates were 0.100, 0.075, and 0.085 for respiratory disease, scours, and stayability, respectively. Solutions for estimated breeding values for respiratory disease and scours were transformed from disease risk to disease resistance by reversing the signs before calculating genetic correlations such that higher values of scours, respiratory disease, and stayability were favored. There was a moderate favorable genetic correlation estimate between respiratory disease resistance and stayability of 0.675. However, genetic correlation estimates between respiratory disease resistance and scours resistance (0.148) and between scours resistance and stayability (0.165) were low. Estimated breeding value correlations between calf health traits and other traits evaluated nationally were generally low in magnitude. The strongest correlation estimates were with longevity, particularly between stayability and heifer livability (0.217) and between stayability and cow livability (0.288); respiratory disease resistance was also favorably correlated with heifer (0.190) and cow (0.178) livability. Correlations with cow health traits were generally low and unfavorable. Linear models including the random effect of herd-by-sire indicated that herd-by-sire accounted for approximately 2% of phenotypic variance for scours and stayability, which may indicate a genotype by environment interaction effect for these traits. In conclusion, there is significant genetic variation in organic calf health, and there was evidence of genotype by environment interaction.

Short communication: Associations of serum biomarkers of stress and inflammation measured at arrival with health, mortality, and growth of calves transported within the first 4 days of life.

The objective of this study was to assess the association between serum concentrations of haptoglobin (Hp), cortisol, and l-lactate following transport of dairy heifer calves within their first week of life with health, mortality, and growth during the preweaning period. Blood samples were collected at arrival and included a cohort of 168 Jersey and Jersey-cross calves from 8 different sources located in Minnesota. All calves were raised at a single facility in New Mexico. Incidence of respiratory disease (BRD) and mortality during the preweaning period (60 d of life) were extracted from the farm's software database. Individual body weight was measured at birth and at weaning to estimate average daily gain. No simple linear correlations were found between the biomarkers. The incidence of BRD during the preweaning period was 7.7%. While cortisol and l-lactate serum concentrations were not associated with BRD, Hp was negatively associated with BRD. Receiving operating characteristic curve analysis was performed to determine the optimal threshold value for Hp [threshold ≤0.63 µmol/L (63 µg/mL), area under the curve = 0.65]. A Cox's proportional hazards model revealed that calves with Hp concentration ≤0.63 µmol/L were more likely to be diagnosed with BRD (hazard ratio = 5.0, 95% confidence interval = 1.3-19.0). A mixed linear model showed that calves with Hp concentration ≤0.63 µmol/L tended to have lower average daily gain (454.4 vs. 479.9 g/d) during the preweaning period than calves with Hp >0.63 µmol/L at arrival. Overall mortality of the cohort was 3.5%, and Hp was not associated with mortality. Although circulating concentrations of l-lactate and cortisol measured at arrival were not associated with BRD incidence during the preweaning period of heifer calves transported within the first 4 d of life, calves with serum Hp concentration >0.63 µmol/L were less likely to be diagnosed with BRD and tended to grow more than calves with Hp ≤0.63 µmol/L. Further research is needed to replicate these results in a larger cohort and to better understand the possible influence of greater inflammatory status at arrival on health and growth of calves transported to a calf-raising facility.

A cross-sectional study of associations between herd-level calf mortality rates, compliance with legislation on calf welfare, and milk feeding management in Norwegian dairy herds.

Our aim was to investigate the associations between management factors, compliance with current legislation, and herd-level calf mortality. In a national calf welfare audit, veterinary inspectors from the Norwegian Food Safety Authority assessed compliance with current legislation on calf welfare (n = 912 herds). Nine criteria were assessed and rated as satisfactory (1) or not satisfactory (0): housing, natural behavior, single pens, colostrum feeding, feeding, water, surveillance, illness/injuries, and <5% mortality rate. In addition, a short questionnaire on milk feeding management for 3-wk-old calves was distributed to all national calf welfare audit herds, and data on mortality and disease recordings were obtained from the Norwegian Dairy Herd Recording System (NDHRS). A herd welfare compliance score (WCS) for each farm was constructed, summarizing the results for the individual criteria. Most herds had a high WCS (median 9.0, range 2-9). Fifty-six percent of the national calf welfare audit herds (508/912) responded to the questionnaire. We performed a cross-sectional study using a data set from 431 herds with available data on recorded disease and mortality events from the NDHRS, recordings from the national calf welfare audit, and the questionnaire. A mixed-effects negative binomial model with Norwegian Food Safety Authority district as the random effect was fitted to the data. Of the 416 herds with available data on calf mortality, 108 (25.9%) reported no mortality in 2016, and the median 6-mo mortality rate was 0.064 (interquartile range 0-0.11) dead calves per 6 calf-months at risk, based on NDHRS recordings. Calf mortality rates were higher in herds whose calves did not have free access to water (incidence rate ratio 1.29; 95% confidence interval 1.02-1.64) and higher in herds that had reported calf disease events (incidence rate ratio 1.31; 95% confidence interval 1.09-1.54). Neither the WCS nor any of the calf milk feeding management factors were associated with mortality, but more than half of producers (59.6%) fed less milk than currently recommended for 3-wk-old calves (8 L/d first 3 to 4 wk). These results indicate that a lack of access to water was associated with higher calf mortality rates. Herds with registered calf disease events had a higher incidence rate ratio of mortality. This finding may be linked to suboptimal calf management, leading to more calf diseases and mortality; or it may be that veterinary consultancy occurs too late or only for the worst cases. There is room for improvement in Norwegian dairy calf management, and water should be provided to young calves.

The effect of pair housing on dairy calf health, performance, and behavior.

Individual housing of dairy calves prevails in Europe and North America despite its negative effects on calf development. One of the main reasons is that farmers find individual housing of calves more practical than group housing. A compromise between practice and welfare could be housing calves in pairs. Therefore, we aimed to compare health, feed intake, growth, and behavior in a novel arena of 22 individually (INDI) and 44 pair-housed calves that were randomly assigned a treatment. Diarrhea and respiratory problems were recorded every day for the period of 49 d. Intake of calf starter and milk were measured every day for the period 48 and 49 d, respectively. Calf body weight gains were calculated as average daily gain. Calves were individually tested in a novel arena at 11 to 18 d, and their behavior was recorded according to an ethogram including 8 behavioral categories. Behavioral categories were first diminished by principal component (PC) analysis. We found that 2 PC explained 66% of the total variation in calf behavior. Movement-related behaviors (activity, play, and crossing the stair) loaded positively on PC1, and PC2 had positive loading on self-grooming and negative loading on exploration. There were no effects of housing on calf health, feed intake, or average daily gain. The INDI calves had higher PC1 scores than pair-housed calves, indicating a rebound effect of movement. Our results are consistent with other studies that found no negative effect of pair housing of calves on their health, feed intake, or growth compared with individually-housed calves. The rebound effect of movement-related behaviors of INDI calves in a novel arena implies that individual housing of calves causes activity deprivation by the second week of age.

Colostrum supplementation with n-3 fatty acids does not alter calf outcome on a healthy commercial farm.

Our objective was to supplement colostrum with n-3 fatty acids (FA) to provide anti-inflammatory mediators that may improve the immune response of neonatal calves. Elevated markers of inflammation have been associated with increased occurrence of calf disease in early life, thus decreasing animal productivity. We hypothesized that a colostrum supplement containing 60-mL of a 1:1 ratio fish:flaxseed oil blend with or without 200 mg of α-tocopherol might provide an advantageous start to early life by decreasing oxidative stress and regulating the inflammatory response. Calves were blocked by birth order and randomly assigned to 1 of 3 treatments: no supplement added to colostrum (control), 60 mL of 1:1 fish:flaxseed oil blend, and 60 mL of 1:1 fish:flaxseed oil blend with 200 mg of α-tocopherol. In total, 180 heifer calves (n = 60 per treatment) were enrolled on a commercial farm. After colostrum feeding, all calves were housed in individual hutches and fed milk replacer 3 times per day. Health was scored 3 times per week until weaning at 8 wk of age. Weight, wither height, and heart girth were measured after birth, 3 wk, and 8 wk of age to assess preweaning growth. A subgroup of 54 calves (18 blocks or 18 calves per treatment) were sampled 2 d (± 8 h) after birth to evaluate oxidant status, serum total protein, and inflammatory gene and cytokine protein expression in blood after an in vitro lipopolysaccharide (LPS) challenge as indicators of health and immunity. At 9 wk, calves were transported 18 h to another farm, and medical records were kept as an indicator of disease incidence up to 13 wk of age. Calf mortality was 1.8%, which is below industry average, and exceptional health scores were observed throughout the study. Health scores and growth were similar throughout the preweaning period regardless of treatment. Serum total protein indicated successful passive transfer in all calves, and oxidant status index was not affected by treatments on d 2 of age. Concentrations of tumor necrosis factor α increased with LPS stimulation, but the increase was not altered by treatment. Likewise, leukocyte gene expression of tumor necrosis factor α, IL-8 and IL-10, and cyclooxygenase-2 increased upon LPS stimulation, but the fold change did not differ with treatment. In conclusion, 60 mL of 1:1 ratio fish:flaxseed oil colostrum supplement did not enhance preweaning calf performance. Supplementing n-3 FA in a one-time meal may not provide the anti-inflammatory benefits observed with continuous feeding.