281 Techniques to estimate colostrum quality and the effects of cow age and pre-partum supplement intake levels on colostrum quality and serum IgG levels. (30th November 2020) - Dafoe, Julia M
Abstract: Our study was conducted to evaluate the influence of cow age and supplement intake level during gestation on the quality of colostrum at calving, serum IgG levels of the cow at parturition, and serum IgG levels of the calf 3 days post-partum using two on-farm refractometer methods. Forty-five non-lactating multiparous Angus cows were selected from a contemporary group of 300 cows 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 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 8 feeding stations in a SmartFeed Pro self-feeder system (C-Lock Inc., Rapid City, SD) and measurements were obtained from d 164 to 215 of gestation. Cows were further divided by age comparing young (4, 5, and 6 yr) to old (7 and 8 yr). Cow age did not interact with supplement intake for any of the colostrum or blood serum measurements (P ≥ 0.29). In addition, cow age and supplement intake did not influence colostrum Brix %, calf serum total protein taken 3 d post-partum 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. When regressing values of the two techniques, they were observed to be correlated (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. The lack of colostrum quality differences was likely due to the moderate to good condition of the cows and adequate nutrition 90 d prior to parturition.