Improving the Performance of Dairy Cattle with a Xylanase-rich Exogenous Enzyme Preparation
The objective was to compare effects of two Trichoderma reesei exogenous fibrolytic enzyme preparations (EFE) on the performance of lactating dairy cattle fed a bermudagrass- and corn silage-based TMR. The first EFE (MIX) had increased the efficiency of feed utilization by lactating dairy cows in a previous study and the second xylanase-rich EFE (XYL) was the best of 18 EFE candidates at improving in vitro NDFD and rumen-like fermentation of bermudagrass haylage. Endoglucanase and xylanase activities of MIX and XYL were 2,087 and 2,714 and 10,549 and 26,926 µmol/min per g, respectively. Sixty-six lactating Holstein dairy cows in early lactation (588 ± 75 kg; 21 ± 5 DIM) were grouped by previous milk production and parity and randomly assigned to Control (CON), XYL, or MIX treatments. The XYL and MIX EFE were added to the diet just before feeding at rates of 1 and 3.4 mL/kg of TMR DM, respectively. Cows were fed experimental diets for 70 d after they were fed a common diet for an 11-d covariate period. The statistical model included effects of enzyme, parity, week and their interactions as well as covariate milk production or DMI. The random effect was cow nested within treatment and parity. Body weight and condition score were not affected by treatment. Compared to CON, application of XYL increased (P < 0.05) intake (kg/d) of DM (28.6 vs. 27.4), OM (26.7 vs. 25.5) and CP (4.7 vs. 4.5) but MIX did not. Cows fed XYL had greater milk yield (kg/d) during wk 3 (41.2 vs. 39.8; P < 0.10), 6 (41.9 vs. 40.1; P < 0.05), and 7 (42.1 vs. 40.4; P < 0.05) as did those fed MIX during wk 6 (41.5 vs. 40.1; P < 0.10), 8 (41.8 vs. 40.0; P < 0.05), and 9 (40.9 vs. 39.5; P < 0.10). Cows fed XYL tended (P < 0.10) to produce more (kg/d) FCM (41.8 vs. 40.7) and fat yield (1.48 vs. 1.44) than those fed CON. Feeding with the EFE increased milk production by dairy cows.