The objective of this study was to conduct a large-scale investigation of colostrum composition and yield and an evaluation of factors affecting them. In this study, 1017 clinically healthy Holstein cows from 10 farms were used. The colostrum TS were measured using a digital Brix refractometer. Fat, protein and lactose content were determined using an infrared Milk Analyzer. Statistical analysis was conducted using a series of univariate general linear models. The mean (±SD) percentage of colostrum fat, protein, lactose and TS content were 6.37 (3.33), 17.83 (3.97), 2.15 (0.73) and 25.80 (4.68), respectively. Parity had a significant positive effect on the protein and TS content and a negative one on fat content. The time interval between calving and colostrum collection had a significant negative effect on the fat, protein and TS contents and a positive one on lactose. Colostrum yield had a significant negative effect on the protein and TS content, and it was affected by all factors considered. In addition to TS, the evaluation of the colostrum fat content appears essential when neonates’ energy needs are considered. The Brix refractometer, an inexpensive and easy to use devise, can be used effectively in colostrum quality monitoring.

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This study investigated the profile of locomotion score and lameness before the first calving and throughout the first (n = 237) and second (n = 66) lactation of 303 Holstein cows raised on a commercial farm. Weekly heritability estimates of locomotion score and lameness, and their genetic and phenotypic correlations with milk yield, body condition score, BW and reproduction traits were derived. Daughter future locomotion score and lameness predictions from their sires' breeding values for conformation traits were also calculated. First-lactation cows were monitored weekly from 6 weeks before calving to the end of lactation. Second-lactation cows were monitored weekly throughout lactation. Cows were locomotion scored on a scale from one (sound) to five (severely lame); a score greater than or equal to two defined presence of lameness. Cows' weekly body condition score and BW was also recorded. These records were matched to corresponding milk yield records, where the latter were 7-day averages on the week of inspection. The total number of repeated records amounted to 12 221. Data were also matched to the farm's reproduction database, from which five traits were derived. Statistical analyses were based on uni-and bivariate random regression models. The profile analysis showed that locomotion and lameness problems in first lactation were fewer before and immediately after calving, and increased as lactation progressed. The profile of the two traits remained relatively constant across the second lactation. Highest heritability estimates were observed in the weeks before first calving (0.66 for locomotion score and 0.54 for lameness). Statistically significant genetic correlations were found for first lactation weekly locomotion score and lameness with body condition score, ranging from −0.31 to −0.65 and from −0.44 to −0.76, respectively, suggesting that cows genetically pre-disposed for high body condition score have fewer locomotion and lameness issues. Negative (favourable) phenotypic correlations between first lactation weekly locomotion score/lameness and milk yield averaged −0.27 and −0.17, respectively, and were attributed to management factors. Also a phenotypic correlation between lameness and conception rate of −0.19 indicated that lame cows were associated with lower success at conceiving. First-lactation daughter locomotion score and/or lameness predictions from sires' estimated breeding values for conformation traits revealed a significant linear effect of rear leg side view, rear leg rear view, overall conformation, body condition score and locomotion, and a quadratic effect of foot angle.

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Dairy cows face precipitous metabolic adaptations during the first postpartum week. Increasing knowledge of their hematologic profiles during this period could benefit both veterinary clinical pathologists and bovine practitioners. The objectives of this study were: (a) to establish period‐specific RIs for Holstein dairy cows and (b) to assess the potential simultaneous effect of several factors on hematology parameters. Blood samples from clinically healthy cows of nine herds were used to establish hematology RIs for these periods. There were 68 cows in the prepartum period (PP), 247 and 218 cows at 2 and 8 days after calving (2 and 8 days in milk [DIM 2 and DIM 8], respectively), and 87 cows in peak lactation (PL). A complete blood count evaluation was performed using the ADVIA 120 analyzer. Linear models estimated the analytes associated with parity. RIs were calculated with Reference Value Advisor. Parity had a significant effect on analytes at all stages. Marked differences were evident between DIM 2 and 8 regarding red blood cell (RBC) counts, hematocrits, hemoglobin concentrations, and white blood cell (WBC), monocyte, and eosinophil counts. Reference intervals of RBC counts, hematocrits, and hemoglobin concentrations at DIM 2 were higher than those at PP and PL. This study provides evidence that period‐specific RIs should be used for Holstein cows when making clinical decisions, especially during the critical first week postpartum.