摘要：Scarcity of data exists on potential use of exogenous enzymes for young calves. The objective of this study was to assess the effects of applying Exogenous Non-starch Polysaccharidases (ENP) to pre-weaning starter concentrate on starter intake, nutrient digestibility and calf growth. Eighteen neonatal Holstein calves (47.9±2.5 kg body weight) were monitored for 84 day. Treatments included pre-weaning calf starters with 1) no enzyme additives (C), 2) enzyme additive A (EA, 0.6 mL kg-1 starter), or 3) enzyme additive B (EB, 1.9 mL kg-1 DM of starter). The activity of endo-cellulase, exo-cellulase and xylanase was measured using carboxymethyl cellulose, filter paper test and oat spelt, as the respective substrates. The resulting activity (μ mol/mL/min) of exo-cellulase, endo-cellulase and xylanase were respectively 1437, 788 and 7476 for EA and 1446, 1350 and 5091 for EB. No enzymes were added to post-weaning diet. Weaning Criterion (WC) was defined as the calf age at a daily intake of 680 g starter and estimated with regression equations. Mixed models of repeated measures with best fitted covariance structures were used to analyze the data. The calves fed EA-supplemented starter had higher NDF apparent total tract digestibility at week-4, but not at week-8, compared to control and EB-fed calves. However, NDF digestibility was lower at week-12 in ENP-fed calves than in control calves. The ENP did not affect the average daily starter intake, growth rate and WC. Overall, applying ENP to pre-weaning calf starter did not improve calf performance in this study. Further studies preferably using a mixture of cell-content and cell-wall polysaccharidases in both pre- and post-weaning starters would be warranted.
