Genetic Parameters of Serum Total Protein Concentration Measured with a Brix Refractometer in Holstein Newborn Calves and Fresh Cows.

The objective was to estimate the genetic parameters of serum total protein concentration in newborn calves (calfSTP) and post parturient dairy cows (cowSTP). The study included 1013 calves and 989 cows from 10 dairy farms. Calf blood samples were collected 24-48 h after parturition while cow blood and colostrum samples were collected in the first 24 h after calving. Blood serum total protein and colostrum total solids content were determined using a Brix refractometer. Chemical analysis of colostrum was performed with Milkoscan. Univariate mixed linear models were used to estimate the heritability of calfSTP and cowSTP and their genetic and phenotypic correlations with colostrum traits. The heritability estimates of calfSTP and cowSTP were 0.21 and 0.20 (p < 0.05), respectively. Strong genetic correlations (r > 0.90) were detected between calfSTP and colostrum total solids and protein content (p < 0.05). Corresponding phenotypic correlations were 0.31-0.33 (p < 0.05). No genetic or phenotypic correlations were detected with colostrum fat content while the respective correlations with lactose were negative (-0.82 and -0.19, p < 0.05). No genetic correlations were detected between cowSTP and colostrum traits and only a low negative phenotypic one with lactose was detected. The results confirm that genetic selection aiming to improve the passive transfer of immunity in newborn calves and general fresh cow health would be feasible.

Hematology reference intervals during the prepartum period, first week after calving, and peak lactation in clinically healthy Holstein cows.

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.

Evaluation of Factors Affecting Colostrum Quality and Quantity in Holstein Dairy Cattle.

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.