不同分级指数燕麦干草-苜蓿干草组合对牦牛瘤胃体外发酵的影响

Influences of Oat Hay and Alfalfa Hay Combination with Different Grading Indexes on Rumen Fermentation of Yak in Vitro

为通过分级指数(GI)优化牦牛日粮粗饲料营养组合,将燕麦干草和苜蓿干草分别以5种比例进行混合,制成GI为7.24、6.40、5.56、4.72和3.88的干草组合进行牦牛瘤胃体外发酵试验,分别发酵3、6、12、24和48 h,测定不同组合在各发酵时段的累积产气量(gas production,GP)、干物质降解率(dry matter disappearance in vitro,DMDIV)、中性洗涤纤维降解率(neutral detergent fiber degradation in vitro,NDFDIV)、氨态氮(ammonia nitrogen,NH 3-N)、微生物蛋白(microbial protein,MCP)和挥发性脂肪酸(volatile fatty acids,VFAs)等,研究不同比例干草组合在牦牛瘤胃中动态发酵规律。结果表明,发酵3~48 h,GI=6.40组合的GP、NDFDIV、NH 3-N、MCP和VFAs均高于或显著高于其他处理(P<0.05),且均随着GI减小呈现出先升高后降低的趋势;发酵24~48 h,DMDIV随GI减小呈现出先增加后降低的趋势,其中,GI=6.40组合的DMDIV最高。综合组合效应指数结果表明,GI=6.40和5.56组合在不同发酵时间均产生了正组合效应;而GI=3.88组合则均为负组合效应;GI=7.24和4.72组合在发酵24~48 h产生了正组合效应。由此可见,燕麦干草和苜蓿干草组合的GI为6.40时牦牛瘤胃体外发酵效果最优,为提高粗饲料的合理搭配和青藏高原舍饲牦牛的生产性能奠定了理论基础。

In order to optimize the forage nutritional combination of yak diet with the grading index(GI),five combinations of alfalfa hay and oat hay with different GI(7.24,6.40,5.56,4.72,3.88)were selected to study rumen fermentation in vitro of yak.The fermentation time was set for 3,6,12,24 and 48 h.The results showed that the gas production(GP),neutral detergent fiber degradation in vitro(NDFDIV),ammonia nitrogen(NH 3-N),microbial protein(MCP),volatile fatty acids(VFAs)of GI=6.40 combination were higher or significantly higher than those of other combination treatments in 3~48 h fermentations,which showed firstly increasing and then decreasing trend with the decreasing of GI.In treatments of 24~48 h fermentations,the dry matter disappearance in vitro(DMDIV)showed a trend of increasing first and then decreasing as GI decreasing,which reached the maximum value in GI=6.40 treatment.The multiply factors associative effects indexes(MFAEI)showed positive combination effects in treatments of GI=6.40 and 5.56 combination,while MFAEI showed negative combination effect in treatments of GI=3.88 combination.Overall,the effect of rumen fermentation in vitro of yak with GI=6.40 alfalfa hay and oat hay combination was best,which provided theoretical foundation for improving the reasonable collocation of roughage and the performance of house-feeding yaks on the Qinghai-Tibet Plateau.