Rumen fermentation and bacterial communities in weaned Chahaer lambs on diets with different protein levels

We evaluatedthe effects of diets with different crude protein （CP） levels on growth performance, rumen fermentation and bacterial communities in weaned Chahaer lambs. 128 weaned Chahaer lambs （（20.56±1.43） kg body weight; ram：ewe 1：1） aged （61±1.85） d were randomly alotted to one of four diets with CP content of 11.17% （T1）, 12.06% （T2）, 13.40% （T3） or 14.36% （T4）.Ruminal fermentation parameters were measured and bacterial communities were analysed using PCR-dena-turing gradient gel electrophoresis （PCR-DGGE） and quantitative PCR. The average daily gain and feed utilization efifciency in T3 were higher than those in the other groups （P〈0.05）, although the dry matter intake and metabolizable energy intake were similar. Total volatile fatty acid concentration in the ruminal lfuid of T3 was lower than that of T1 （P=0.011）, T2 （P=0.008） or T4 （P=0.309）. The ammonia nitrogen concentration and acetate/propionate ratio of ruminal lfuid were signiifcantly higher in lambs fed the higher CP diets, whereas the molar concentrations of propionate and butyrate of ruminal lfuid were lower. The rumen bacterial community was similar in T2 and T3 which shown more stable and diverse rumen microbes ecosystem compared with the other groups. The DGGE proifles and phylogenetic tree indicated thatBacteroides uniformis,Clostrid-iumalkalicellulosi,Alkalibaculum bacchiandSaccharofermentanssp.were common bacterium of Chahaer lamb rumen. B. uniformis,C.alkalicelulosi,Saccharofermentanssp. andGracilibacter thermotolerans,which belong to the Bacteroidetes and Firmicutesphyla,were the dominant species in the rumen of lambs fed 13.40% CP.However,Ruminococcus albus, Ruminococcus lfavefaciensand Butyrivibrio ifbrisolvenswerenot differentin lambs fed different CP diets. Therefore, it could be concluded thatB. uniformis,C.alkalicelulosi,A. bacchiandSaccharofermentanssp.were common bacteria of Chahaer lamb rumen. Furthermore, the dietary CP of 13.04% could improve performance and change rumen fermentation model by increasing the dominant species’ peak intensities ofB. uniformis,C.alkalicelulosi,Saccharofermentanssp. and Gracilibacter thermotoleransand stabilizing rumen microbial ecosystem.

Benefits of tributyrin on growth performance,gastrointestinal tract development,ruminal bacteria and volatile fatty acid formation of weaned Small-Tailed Han lambs

This study aimed to determine the effects of tributyrin on growth performance,gastrointestinal tract development,ruminal bacteria and volatile fatty acid(VFA)formation.Thirty healthy weaned SmallTailed Han female lambs at 3 months old with BW 27.5±4.1 kg(mean±SD)were randomly assigned to five groups of six lambs each,and each group received tributyrin at 0,0.5,1.0,2.0 and 4.0 g/kg in feed.Weights were measured before the start and end of the study.After 15 d adaptation,DMI,feed,faeces and urine were recorded every week.Lambs were sacrificed at d 75.Compared to lambs fed no tributyrin,lambs fed 4.0 g/kg tributyrin had higher average daily BW gain(P=0.04)and DMI(P<0.01).Tributyrin reduced nitrogen(P<0.01),Ca(P<0.01)and P(P<0.01)losses derived from faeces and urine.The mostly important,tributyrin increased dorsal sac thickness(P<0.01),papillae length(P=0.04)and width(P<0.01),ventral sac papillae length(P<0.01)and width(P<0.01),caudodorsal blind sac thickness(P=0.02),papillae length(P<0.01)and width(P<0.01).Furthermore,tributyrin increased thicknesses of both the duodenum(P<0.01)and ileum(P=0.01),and villus heights of the duodenum(P=0.01),ileum(P<0.01),jejunum(P<0.01)and caecum(P=0.02),but tributyrin decreased duodenal(P<0.01)and caecal crypt depths(P<0.01).Tributyrin reduced rumen pH(P<0.01)while promoting total VFA concentration(P<0.01).Tributyrin improved the structure of rumen bacteria by enhancing Clostridium(P=0.04),Butyrivibrio(P<0.01),Streptococcus(P=0.04),Prevotella(P=0.04),Ruminobacter(P=0.02)and Fibrobacter(P=0.03).In conclusion,tributyrin could stimulate gastrointestinal tract development by enhancing colonization of rumen VFA-producing bacteria,and dietary supplementation of tributyrin at 4.0 g/kg of DM was recommended for the weaned lambs.