Associative effects of supplementing rice straw-based diet with cornstarch on intake, digestion, rumen microbes and growth performance of Huzhou lambs.
Thirty-six male Hu lambs consuming a rice straw-based diet were used in a 60-day trial to study the associative effects of cornstarch supplementation on intake, digestion, ruminal microbial population and growth performance. All animals were fed rice straw ad libitum together with 160 g/day of rapeseed meal and supplemented with cornstarch at levels of 0 (control), 60, 120 or 180 g/day, respectively. Increment of supplementary cornstarch showed little influence on rice straw intake. Optimal growth performance and highest apparent digestibility of organic matter was achieved in the 120 g/day cornstarch group (P < 0.05), while the digestibilities of neutral detergent fiber and crude protein were significantly decreased by 180 g/day cornstarch (P < 0.05). Similar results were observed for carboxymethyl cellulose activity and relative populations of cellulolytic bacteria (Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogene). Blood urea nitrogen was reduced by supplementary cornstarch, indicating enhanced protein utilization efficiency. Carcass traits were all significantly improved by supplementary cornstarch. These results suggested that proper amounts of starch supplementation (within 0.5% BW) has little adverse effect on forage utilization, but could effectively improve growth performance. High levels of cornstarch, however, would decrease cellulase activity and populations of cellulolytic bacteria, and hence the digestibility of forage.
Zhang
Xian-Dong
XD
College of Animal Sciences, Ministry of Education Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou, China.
Wang
Jia-Kun
JK
Chen
Wei-Jian
WJ
Liu
Jian-Xin
JX
D000821:Animal Feed; D000818:Animals; D002480:Cellulase / Q000378:metabolism; D008297:Male; D012417:Rumen / Q000382:microbiology*; D012756:Sheep / Q000254:growth & development*; D013213:Starch / Q000008:administration & dosage*
D013213:Starch; D002480:Cellulase; C019826:carboxymethylcellulase