Effect of Quantity of Protein in the Concentrate Mixture on the Growth, Reproductive Development, and Semen Production of Dairy Bulls

Abstract

Summary Holstein bull calves 1–2 wk of age were assigned to three levels of dietary protein, with the low protein, normal protein, and high protein groups receiving concentrate mixtures containing 10, 16, and 22% protein, respectively. A single source of hay was used for all groups. 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 104 wk of age. At 104 wk of age the 18 unrelated bulls were removed from experiment; the three sets of monozygous twins were kept on experiment and data collected to 208 wk of age. No statistically significant differences among experimental treatments were noted in any of the criteria used in evaluation. It is concluded that when good-quality hay is fed liberally, a concentrate mixture containing 10% protein is adequate for normal growth and reproductive development of dairy bulls.