Effect of Total Digestible Nutrient Intake from Birth to Four Years of Age on Growth and Reproductive Development and Performance of Dairy Bulls

Neonatal Holstein bull calves were assigned to four levels of energy intake representing 70, 100, 115, and 130% of the National Research Council recommended TDN allowances for growing dairy calves. The groups were designated L, N, M, and H, respectively. Two additional groups were on a changeover at 104 wk. of age--Lit changed from 70 to 130% and HL from 130 to 70%. Data were collected on growth (body weight, height at withers, and heart girth), onset of semen production, and semen quantity and quality until the bulls reached 208 wk. of age. The average age at the onset of semen production was 61, 45, 41, and 44 wk., respectively, for the L, N, M, and H groups. Comparable figures for body weight at the onset of semen production were 523, 643, 675, and 784 lb.