CASE STUDY: Effects of Amylase on Rumen Development in Neonatal Dairy Calves1

Two trials, each with 15 male Holstein calves, were conducted to determine whether the addition of amylase to calf starter could affect rumen development and calf performance. Amylase was added to calf starter at a rate of 0, 6, or 12 g/d, fed in the first 200 g of grain consumed each day. Grain and milk intake, fecal scores, and health were monitored daily. Body weight, hip width, heart girth, withers height, and blood β-hydroxybutyrate were measured weekly 4 h after morning feeding. Reticulorumens were harvested at 35 d in Trial 1 and at 42 d in Trial 2. Rumen tissue growth was measured in 9 sampling areas for papillae length and width and rumen wall thickness. Amylase activity differed between trials; calves in Trial 1 were fed 0, 6,762, or 13,524 dextrinizing units (DU)/d, and in Trial 2 calves were fed 0, 4,710, or 9,420 DU/d. No differences were detected in calf health, growth, grain intake, or blood levels of β-hydroxybutyrate. Rumen development results from these 2 trials suggest that amylase moderately enhanced rumen tissue growth when fed in calf starter. In the first trial 6,762 DU/d was more effective than 13,524 DU/d, and in the second trial 9,420 DU/d tended to be more effective than 4,710 DU/d. When combined, these results suggest that an adequate level of amylase to affect rumen tissue growth may lie between 6,762 and 9,420 DU/d.