Effects of Undegradable Intake Protein on Milk Yield, Bun and Dry Matter Digestibility in Lactating Goats Fed Ammoniated Corn Stover

摘要

Protein supplementation can improve productivity of goats consuming low quality forages by either increased feed intake or by increased efficiency on nutrient usage. An experiment was conducted to evaluate the effects of different levels of UIP on milk yield, dry matter digestibility and blood urea nitrogen in lactating goats fed ammoniated corn stover. About 18 young goats 32.3±2.1 kg initial body weight and 8-10 weeks postpartum were used in the experiment. Goats were randomly assigned to one of the three treatments. All goats received a basal diet of 90% ammoniated corn stover (92% DM, 11% CP, 75% NDF) plus 10% alfalfa hay (90% DM, 18% CP, 60% NDF) once a day at 2% BW at 0800 h throughout the trial. Water and salt mineral mix were available at all times. Animals were individually supplemented once daily at 0800 h, receiving 100 g of one of the three supplement treatments; low UIP (LUIP; 51% CP, 70% RDP:30% UIP), medium UIP (MUIP; 50.8% CP, 60% RDP:40% UIP) or high UIP (HUIP; 50.7% CP, 50% RDP:50% UIP). On day 19 and day 42 of the treatment period milk production was assessed milking by hand. From 40-42 day fecal collection bags were fitted to the animals to assess total fecal and urine output. On day 43 of the experimental period one blood sample was collected before supplementation and every hour for 6 h after supplementation via jugular venipuncture. Nutrient digestibility and body weight change were analyzed by analysis of variance for a completely randomized design while milk yield and blood urea nitrogen where analyzed by repeated measurement. Feed intake was similar (p = 0.43) between treatments while goats in the BP group showed the highest average daily gain (p = 0.5). Milk yield (p = 0.53) and BUN concentration (p= 0.51) were no influenced by supplements. Protein supplementation did not influence nutrients digestibility between treatments. These results suggest that protein supplementation can diminish body weight loss and support low milk yield in goats consuming ammoniated corn residues.