Abstract #W28

# W28
Performance of Jersey calves born from dams treated with recombinant bovine somatotropin during the periparturient period.
Paula R. B. Silva*1, Henrique F. Soares1, Gabriel D. Bombardelli1, Ricardo C. Chebel1,2, 1University of Minnesota, St Paul, MN, 2University of Florida, Gainesville, FL.

Objectives of the current experiment were to evaluate the performance of Jersey calves born from Jersey dams treated with recombinant bovine somatotropin (rbST) during the periparturient period. Jersey dams were assigned randomly to control (n = 264) and rbST (125 mg of rbST every 7 d from −21 to 21 d relative to calving; n = 258) treatments. A sub-sample (control = 19, rbST = 19) of cows had colostrum samples collected at calving to determine IgG concentration. Male Jersey calves were sold at birth, leaving 199 and 173 calves from control and rbST cows. Calves born from cows enrolled in this experiment were fed pooled colostrum (4 L) twice within 6 h of birth, were housed in individual hutches from birth to 21 d of age, and in group pens with automated calf feeders from 22 d of age to weaning (60 d of age). Calves were weighed individually at birth (control = 198, rbST = 172) and at weaning (control = 122, rbST = 107) and average daily gain in the first 60 d of life was calculated. Calves were observed daily for diagnosis of diarrhea and respiratory illness. Data referent to health and performance to 60 d of age is reported herein. Continuous data were analyzed by ANOVA and dichotomous data were analyzed by logistic regression. Colostrum IgG concentration was not different between treatments (control = 87.6 ± 6.4, rbST = 94.5 ± 6.4 g/L; P = 0.45). Treatment did not affect birth weight (control = 27.9 ± 0.4, rbST = 27.4 ± 0.5 kg; P = 0.24), weaning weight (control = 70.5 ± 1.8, rbST = 71.1 ± 1.8 kg; P = 0.60) or average daily gain (control = 0.74 ± 0.03, rbST = 0.74 ± 0.03 kg/d; P = 0.88). There was a greater likelihood of calves born from rbST cows to be diagnosed with diarrhea (control = 1.0, rbST = 4.6%; P = 0.05) but treatment did not affect the likelihood of pneumonia (control = 25.6, rbST = 27.8%; P = 0.61) and death (control = 10.6, rbST = 13.3%; P = 0.41) within the first 60 d of life. Treatment of periparturient Jersey cows with small doses of rbST did not affect performance and health of calves up to 60 d of life.

Key Words: recombinant bovine somatotropin, Jersey calves, performance