Effect of Saccharomyces cerevisiae on alfalfa nutrient degradation characteristics and rumen microbial populations of steers fed diets with different concentrate-to-forage ratios  

作　　者：Gengzhi Ding Ying Chang Liping Zhao Zhenming Zhou Liping Ren Qingxiang Meng 

机构地区：[1]State Key Laboratory of Animal Nutrition,College of Animal Science and Technology,China Agricultural University [2]Lallemand biology Technology(Beijing) Co.Ltd.

出　　处：《Journal of Animal Science and Biotechnology》2014年第4期430-438,共9页畜牧与生物技术杂志（英文版）

基　　金：financially supported by the Earmarked Fund for ModernAgro-Industry Technology Research System(Beef Cattle and Yaks,CARS-38);the Chinese Universities Scientific Fund(No.2013QT034)

摘　　要：Live yeast（Saccharomyces cerevisiae） constitutes an effective additive for animal production;its probiotic effect may be related to the concentrate-to-forage ratio（CTFR）.The objective of this study was to assess the effects of S.cerevisiae（SC） on fiber degradation and rumen microbial populations in steers fed diets with different levels of dietary concentrate.Ten Simmental × Local crossbred steers（450 ± 50 kg BW） were assigned to a control group or an SC group.Both groups were fed the same basal diet but the SC group received SC supplementation（8 × 10^9 cfu/h/d through the ruminal fistula）following a two-period crossover design.Each period consisted of four phases,each of which lasted 17 d：10 d for dietary adaptation,6 d for degradation study,and 1 d for rumen sample collection.From the 1^（st） to the 4^（th） phase,steers were fed in a stepwise fashion with increasing CTFRs,i.e.,30：70,50：50,70：30,and 90：10.The kinetics of dry matter and fiber degradation of alfalfa pellets were evaluated;the rumen microbial populations were detected using real-time PCR.The results revealed no significant（P〉 0.05） interactions between dietary CTFR and SC for most parameters.Dietary CTFR had a significant effect（P〈 0.01） on degradation characteristics of alfalfa pellets and the copies of rumen microorganism;the increasing concentrate level resulted in linear,quadratic or cubic variation trend for these parameters.SC supplementation significantly（P〈 0.05） affected dry matter（DM） and neutral detergent fiber（NDF）degradation rates（c_（DM）,c_（NDF）） and NDF effective degradability（ED_（NDF））.Compared with the control group,there was an increasing trend of rumen fungi and protozoa in SC group（P 〈 0.1）;copies of total bacteria in SC group were significantly higher（P〈 0.05）.Additionally,percentage of Ruminobacter amylophilus was significantly lower（P〈 0.05）but percentage of Selenomonas ruminantium was significantly higher（P〈 0.05） in tLive yeast（Saccharomyces cerevisiae） constitutes an effective additive for animal production;its probiotic effect may be related to the concentrate-to-forage ratio（CTFR）.The objective of this study was to assess the effects of S.cerevisiae（SC） on fiber degradation and rumen microbial populations in steers fed diets with different levels of dietary concentrate.Ten Simmental × Local crossbred steers（450 ± 50 kg BW） were assigned to a control group or an SC group.Both groups were fed the same basal diet but the SC group received SC supplementation（8 × 10^9 cfu/h/d through the ruminal fistula）following a two-period crossover design.Each period consisted of four phases,each of which lasted 17 d：10 d for dietary adaptation,6 d for degradation study,and 1 d for rumen sample collection.From the 1^（st） to the 4^（th） phase,steers were fed in a stepwise fashion with increasing CTFRs,i.e.,30：70,50：50,70：30,and 90：10.The kinetics of dry matter and fiber degradation of alfalfa pellets were evaluated;the rumen microbial populations were detected using real-time PCR.The results revealed no significant（P〉 0.05） interactions between dietary CTFR and SC for most parameters.Dietary CTFR had a significant effect（P〈 0.01） on degradation characteristics of alfalfa pellets and the copies of rumen microorganism;the increasing concentrate level resulted in linear,quadratic or cubic variation trend for these parameters.SC supplementation significantly（P〈 0.05） affected dry matter（DM） and neutral detergent fiber（NDF）degradation rates（c_（DM）,c_（NDF）） and NDF effective degradability（ED_（NDF））.Compared with the control group,there was an increasing trend of rumen fungi and protozoa in SC group（P 〈 0.1）;copies of total bacteria in SC group were significantly higher（P〈 0.05）.Additionally,percentage of Ruminobacter amylophilus was significantly lower（P〈 0.05）but percentage of Selenomonas ruminantium was significantly higher（P〈 0.05） in t

关 键 词：Concentrate-to-forage ratios In situ Real-time PCR Rumen microorganism Steers 

分 类 号：S823.5[农业科学—畜牧学]