Techniques to Estimate Colostrum Quality and the Effects of Cow Age and Pre-Partum Supplement Intake Levels on Colostrum Quality and Serum IgG Levels

This study evaluated cow age and supplement intake level during gestation on the quality of colostrum at calving, cow serum immunoglobulin G (IgG) levels at parturition, and serum IgG levels of the calf 3-days post-partum using two refractometer methods. Forty-five multiparous Angus cows were selected from a contemporary group of 300 cows that were winter grazing northern mixed grass prairie rangelands with free choice protein supplement. Specifically, 15 first service bred cows were selected for each of the following winter grazing supplement intake treatment groups- 1) low supplement intake (> -0.75 SD); 2) average supplement intake (± 0.50 SD); 3) high supplement intake (> +0.75 SD). Supplement intakes were measured using a SmartFeed Pro self-feeder system with 8 feeding units. Measurements were obtained from day 164 to 215 of gestation. Cows were further divided by age comparing young (4, 5, and 6 yr) to old (7, 8 and 9 yr). The results of this study suggest that cow age did not interact with supplement intake for colostrum or blood serum measurements (P ≥ 0.29). In addition, cow age and supplement intake did not influence colostrum Brix %, calf serum total protein, or cow serum total protein taken at birth (P ≥ 0.14). The optical refractometer was found to be a good alternative to the more expensive digital refractometer (P < 0.01; R = .96). In summary, cow age and supplement intake levels of mature cows during the mid to late stages of gestation did not influence colostrum quality at birth.