Effects Of Fermented Distiller’s Grains On The Production Performance And Rumen Bacteria Composition Of Finishing Yaks

The present study is conducted in vitro and in vivo experiments,to evaluate the effects of using different proportions of fermented distiller’s grains as a diet protein source on gas production,growth performance,apparent nutrient digestibility,rumen fermentation and bacteria composition of finishing yaks.This experiment aims to provide the basic research application of fermented distiller’s grains on finishing yaks.Experiment 1.Effects of dietary protein replament by fermented distiller’s grains on fermentation performance in vitroThe objective of this study was to explore the differences in gas production,gas composition and fermentation indexes by rumen fermentation in vitro,when different proportions of dietary protein was replaced by fermented distiller’s grains（CP:24.35%CF:11.30%）.In this experiment,four groups were set at same nutrient level,which replaced 0%（control group）,5.5%（trial group I）,11%（trial group II）and16.5%（trial group III）of dietary protein respectively.Samples of gas and rumen fluid were collected at 12h,24h and 48h,and divided into 5 repetitions and blank.The results showed that:1)The total volatile fatty acids,acetate,propionate and butyrate concentrations were significantly increased,when 5.5%dietary protein was replaced.While the substitution ratio further increased,the gas production decreased.The proportion of methane（CH₄）at 48h was the highest when 16.5%dietary protein was repalced（P<0.05）.2)The cumulative gas production,rapid fermentation gas production and potential gas production were significantly increased,when 11%dietary protein was repalced（P<0.05）.3)MFAEI:5.5%subsititution group>11%subsititution group>16.5%subsititu-tion group.According to all the indexes,the effect of fermented distiller’s grains protein replacing 5.5%and 11%dietary protein in vitro fermentation was better.Experiment 2.Effects of dietary protein repalment by fermented distiller’s grains on yak’s growth performance and rumen bacteria compositionIn this study,two trial groups（5%and 11%subsititution groups）with good MFAEI were selected in feeding experiment,and the differences in yak’s growth performance and rumen bacteria composition were investigated.A total of thirty3-year-old finishing yaks（body weight 188.2±13.9kg）,were randomly selected and divided into 3 groups,with 10 yaks in each group.Fermented distiller’s grains was used as a protein source,respectively replacing 0%（control group）,5.5%（trial group I）and 11%（trial group II）dietary protein.The adjustment period was 15d,and the formal period was 60d.Results showed that:1)When 5.5%of dietary protein was replaced by fermented distiller’s grains,ADG and the digestibility of DM and NDF of yaks increased and the F/G decreased significantly（P<0.05）.While,the F/G increased in 11%group（P<0.05）.2)The TVFA,acetate,propionate contents of yak rumen fluid were the highest in5.5%group,and acetate/propionate increased significantly in 11%subsititution group（P<0.05）.3)The abundance of Euryarchaeota,Methanobrevibacter and Christensenellace-ae R-7 group was significantly reduced when 5.5%dietary protein replaced by fermented distillers’grains（P<0.05）.However,Saccharibacteria,fibroes,Fibrobacter,Succinivibrionaceae UCG-002 and other bacteria related to fiber degradation increased significantly（P<0.05）.Above all,fermented distillers’grains can be used as a protein source in the diet of finishing Maiwa yak.The suitable replacement ratio is 5.5%,which can improve the species abundance related to energy metabolism and fiber degradation,increase the production of acetate,propionate in rumen,thus improve the daily gain and feed conversion rate.