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Poor vigor at birth has been associated with reduced IgG absorption from colostrum and a reduced vitality in neonatal dairy calves. Some natural compounds, such as green tea extract, may improve vitality in compromised calves. The objective of this randomized controlled trial was to evaluate the potential of supplementing a green tea extract (15 mL) to calves to improve vigor and activity behavior for the first 72 h postnatal. Also, this study aimed to investigate the influence of green tea extract supplementation on calf serum IgG concentration and the apparent efficiency of absorption (AEA) of colostral IgG. Holstein calves (n = 24) weighing 42.49 ± 1.07 kg postnatal received a complete random assignment at 3 h of one 15-mL dose of green tea extract (Calf Perk, TechMix) or distilled water orally before tube feeding colostrum replacer (Premolac Plus IgG, Zinpro) at 4 h postnatal. Two observers assessed for calving time and dystocia by live video stream to retrieve all calves within 2 h postnatal. One veterinarian performed a baseline vigor assessment based on heart rate and response to stimuli on all calves at 2.5 h, before colostrum feeding at 3.75 h, as well as at 24, 48, and 72 h postnatal. Calf blood samples were taken to assess total IgG by radial immunodiffusion assay at 2.5, 6, 12, 24, 48, and 72 h. Calf vitality was also observed continuously by video for all calves to determine whether treatment was associated with attempts to stand, lying time, and exploration of their pen environment for the first 24 h. We used an ordinal logistic model to evaluate the odds of green tea extract improving a calf's vigor category from 2.5 h postnatal to 72 h of age. Vigor score was categorized as abnormal (≤4), average (5), or alert (≥6), with hour as a fixed effect. We also ran mixed linear models to evaluate the effect of extract on total IgG and AEA, with time and dystocia as fixed effects. Five dystocia calves were enrolled (2 control, 3 extract), but assistance was minor (e.g., manual assistance and all were assisted within 1 h). Baseline vigor scores and baseline total IgG were not different between groups. Vigor score category was not associated with green tea extract supplementation (odds ratio 1.17; 95% CI: 0.43-3.15) but increased with time compared with controls. We observed no association of treatment with total IgG or AEA in the calves, suggesting green tea extract does not compromise IgG absorption. Calf vitality, lying behavior, and exploratory behavior were not associated with green tea extract treatment. Our findings suggest that green tea extract supplementation does not affect AEA and serum IgG concentration in calves. Future research should evaluate whether green tea extract improves vitality in calves experiencing severe dystocia.

Diarrhea is the primary cause of morbidity and mortality in dairy calves. Many cases of diarrhea in calves are treated with antimicrobials, increasing the risk of antimicrobial resistance, therefore, creating a need for alternative therapies. The objective of this study was to evaluate the effects of feeding spray-dried maternal derived bovine colostrum replacer at the onset of diarrhea on calf growth and duration and severity of the disease in preweaning dairy calves. At a calf-raising facility in southern Ontario, calves were scored for fecal consistency twice daily on a scale of 0 to 3 and enrolled into the trial when they had 2 consecutive fecal scores of 2 (runny or spreads readily) or one fecal score of 3 (liquid consistency, splatters). Calves were then randomly allocated to receive one of the following 3 treatments: (1) control (CON; n = 35): 8 feedings over 4 d of 2.5 L of milk replacer at a concentration of 130 g/L (26% crude protein and 17% fat); (2) short-term colostrum supplementation (STC; n = 35): 4 feedings over the first 2 d of 2.5 L of a mixture of milk replacer at 65 g/L and bovine colostrum replacer at 65 g/L (26% IgG and 14.5% fat) followed by 4 feedings over 2 d of 2.5 L of milk replacer at a concentration of 130 g/L; or (3) long-term colostrum supplementation (LTC; n = 38): 8 feedings over 4 d of 2.5 L of a mixture of milk replacer at 65 g/L and bovine colostrum replacer at 65 g/L. Serum IgG was determined at arrival to the facility and body weight, days to enrollment since facility arrival, and severity of diarrhea were recorded at enrollment. Daily health exams evaluating fecal consistency were performed for 28 consecutive days after enrollment and body weight was measured at d 0, 1, 2, 3, 4, 7, 14, 21, 28, 42 and 56 after enrollment. The median days to resolution of a case of diarrhea was 3.5 d (range: 0.5-11.5 d), 2.75 d (range: 0.5-11.0 d), and 2.75 d (range: 0.5-7.0 d) in CON, STC, and LTC, respectively. Using a Cox proportional hazards model, it was found that calves in LTC group had faster resolution of diarrhea compared with calves in the CON group. In addition, there was an association between both days to enrollment since facility arrival and body weight and resolution of diarrhea, where calves who were at the facility longer before enrollment and heavier at the onset of diarrhea, resolved diarrhea quicker. In addition, calves with a fecal score of 3 at enrollment took longer to resolve their case of diarrhea. With respect to body weight, a linear regression model was built and found that over the 56 d following enrollment calves in the LTC treatment grew 98 g/d more than calves in the CON group. These results suggest that bovine colostrum may be an effective therapy for diarrhea in preweaning calves.

The objectives of this study were to investigate how milk replacer (MR) allowance and differing concentrations of starch and neutral detergent fiber in starter alters visceral tissue and overall growth of the calf. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) arranged in a 2 × 2 factorial based on daily MR allowance (MRA) and amount of starch in pelleted starter (SPS) as follows: 0.691 kg of MR/d [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch, respectively) and 1.382 kg of MR/day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered to minimize intake. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning, and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Intakes were measured daily, and body weight (BW) and blood samples were recorded and collected weekly. Calves were dissected in wk 8 for visceral tissue measurements. Overall, there was increased MR DM intake for the high- (0.90 ± 0.01 kg/d; ± SE) compared with the low-MRA (0.54 ± 0.01 kg/d) calves, whereas starter DM intake increased in low- (0.47 ± 0.05 kg/d) compared with high-MRA (0.20 ± 0.05 kg/d) calves, which was driven by increases in wk 6, 7, and 8. High-MRA calves had increased BW during wk 2, 3, 4, 5, 6, and 7. The difference in BW disappeared by wk 8, with overall average daily gain having a tendency to be increased in high (0.57 ± 0.04 kg/d) compared with low-MRA (0.50 ± 0.04 kg/d) calves, whereas average daily gain was increased in high-MRA calves during wk 2 and 3 and increased in low-MRA calves during wk 7 and 8. There were several differences throughout visceral tissue measurements, but most notably, an increase in rumen mass (i.e., full, empty, and digesta weights) in low- compared with high-MRA calves, as well as in low- compared with high-SPS calves was observed. The length, width, and 2-dimensional area of rumen papillae were also increased in low- (area: 0.88 ± 0.03 mm

The objective of this study was to validate the precision and accuracy of a milk leukocyte differential tester to identify subclinical mastitis cases in dairy cows. Milk samples from individual quarters (n = 320) of 80 Holstein cows were aseptically collected and analyzed in this study. Each sample was divided into 2 replicate samples after mixing. One replicate was analyzed for somatic cell count (SCC) using the current gold standard of flow cytometry immediately after milking. The second sample was evaluated using the on-farm milk leukocyte differential tester directly after milking, where total leukocyte count (TLC; cells/mL) was obtained. The SCC and TLC were used to calculate somatic cell score (SCS) and TLC score [TLS = log2 (TLC/100,000) + 3]. Two subclinical mastitis thresholds were set: >200,000 (low) and >400,000 (high) cells/mL. First, precision was determined between the 2 methods. Total leukocyte count and calculated TLS from the milk leukocyte differential device were compared with the gold standard using correlation and regression coefficient of determination analyses. Correlation coefficients (r) were 0.97 for TLC and SCC and 0.90 for TLS and SCS. The coefficient of determination for regression (R2) was 0.94 for TLC and SCC and 0.80 for TLS and SCS. Slopes of regression for scores and measures were 0.36 [95% confidence interval (CI): 0.35–0.37] and 0.69 (CI: 0.65–0.73), respectively; both were significantly different from 1. Sensitivity, specificity, and diagnostic accuracy were calculated for correct diagnosis of the 2 SCC thresholds using the gold standard as reference. The sensitivity of the on-farm test was 58% (95% CI: 44 to 71%) and 73% (95% CI: 56 to 86%) for the low and high thresholds, respectively. The specificities for the on-farm test were 100% (95% CI: 99 to 100%) and 100% (95% CI: 98 to 100%) for the low and high thresholds, respectively. Subclinical diagnosis accuracies were 93% (95% CI: 89 to 95%) and 96% (95% CI: 92 to 98%) for the low and high thresholds, respectively. The on-farm milk leukocyte differential tester was precise but not overall accurate for total cell counts; it had high specificity and accuracy for diagnosis compared with a standard diagnostic tool. These results suggest that the tested system is a promising technology to detect subclinical mastitis on-farm.

Many cooling strategies are used to keep cows in thermal homeostasis; however, most of them are applied to the group level, commonly at the feed bunk or milking parlor. The variance of heat stress effects on animals are well known, but with more individualized management in dairy farms, group cooling opportunities are becoming restricted. It is known that dairy cattle are variable in their responses to an increase in heat load. Thus, the first objective of this study was to investigate the effect of 2 mandatory soakings at the exit of the milking parlor and free access to a voluntary soaking system compared with cows with access to a voluntary soaking system only, with no mandatory soakings. The second objective of this study was to assess the heat abatement capability of voluntary soaking of cows by assessing cow physiology, behavior, and milk production. Last, this study aimed to determine the individual use of the voluntary heat abatement system and its relationship with temperature-humidity index (THI). Fifteen mid-lactation Holstein cows were enrolled in this study and had free access to a motion-activated soaker (Cool Sense, Edstrom) located adjacent to the research pen for an 8-wk data collection period. Cows were paired according to parity, milk production, and body weight, and assigned a treatment with or without mandatory soakings twice per day. In the mandatory soaking treatment (MS), cows were soaked using a motion-activated soaker at the exit of the milking parlor and had free access to the voluntary soaker in the pen. Cows in the treatment without mandatory soakings (NMS) were not soaked at the exit of the milking parlor and had free access to the voluntary soaker in the pen. The effects of soaker treatment were analyzed using mixed linear models. The model included treatment, soaker uses per day, pair, mean daily THI, days in milk, daily milk yield, and interaction of treatment with mean daily THI. Study day was specified as a repeated measure, and cow as the subject, using an autoregressive structure. Also, we assessed the relationship of mean soaker use and THI against all variables. There was great individual variation in voluntary soaker use, ranging from 0 to 227 soakings/d (mean ± standard deviation, 13 ± 30 voluntary soakings/d). Treatment did not affect voluntary soaker use (MS, 12.4 ± 1.4 soakings/d; NMS, 14.8 ± 1.4 soakings/d), respiration rate (MS, 57.3 ± 0.4 breaths/min; NMS, 56.4 ± 0.4 breaths/min), or milk yield (MS, 36.5 ± 0.6 kg/d; NMS, 36.2 ± 0.6 kg/d). However, MS cows spent more time ruminating (MS, 558.6 ± 5.2 min/d; NMS, 543.4 ± 5.4 min/d). Temperature-humidity index had a positive relationship with voluntary soaker use and mean respiration rate. In conclusion, voluntary soaker use related positively to the THI, but no major productive, physiological, or behavioral differences were observed between soaking treatments. Furthermore, we found that voluntary soaker use is highly variable among cows and it was related positively to milk yield, where higher producing cows used the soaker more frequently.