Effects of Energy Level on Growth Performance, Slaughter Performance, Ruminal Fermentation Parameters and Rumen Microorganisms Number in House-fed Yaks
This experiment was conducted to investigate the effects of energy level on growth performance,slaughter performance,ruminal fermentation parameters and the number of several rumen microorganisms in house-fed yaks.Single factor randomized block design was adopted in this study,and sixty healthy 3-year-old Maiwa yaks with an average body weight of (192.66±3.64) kg were randomly divided into 3 groups with 20 replicates per group and 1 yak per replicate.Diets for all groups had the same crude protein content (14.81％) and different net energy levels for gain (NEg) with 4.17(LE),4.48(ME) and 4.79(HE) MJ/kg,respectively.The experiment was lasted for 97 days (7-day pretrial period and 90-day feeding trial).The results showed that compared with LE group,average daily gain (ADG) of ME (1 099.89 g/d) and HE (1 019.02 g/d) were increased by 27.26 ％ (P＜0.01) and 17.90 ％ (P＜0.01),respectively,the F/G trended to be significantly decreased (P=0.073) and slaughter rate trended to be significantly increased (P=0.092) than that of LE group.However,no significant difference was found on the dry matter intake (DMI) and net meat percentage among all treatment groups (P＞0.05).With the increase of diet energy level,pH in yak rumen tended to decrease significantly (P=0.064),and that of ME group was the lowest.The increase of diet energy level tended to significantly affect the isobutyric acid concentration (P=0.063) and the ratio of acetic acid to propionic acid (P=0.074).Total volatile fatty acids (TVFA) and acetic acid concentration of ME group were significantly higher than the other two groups (P＜0.05),of which the valeric acid concentration was extremely significantly increased with the increase of the diet energy level (P＜0.01).Increasing dietary energy level had a trend to decrease the relative content of R.flavefaciens,but there was no significant effects on the relative content of R.albus and F.succinogenes (P＞0.05).In conclusion,we recommend 4.48 MJ/kg (DM basis) as a diet appropriate NEg level for the barn feeding of fattening yak under this experimental condition.
国家科技期刊平台
NSTL
万方数据
维普
