| The objectives of this study were to investigate the effects of total mixed diets with sodium bicarbonate or different concentrations of probiotics on fattening sheep performance,rumen fermentation and rumen bacterial diversity in pen-fed condition.Fifteen sheep with good health,aged at 3 months and similar in body weight(20.3±1.98 kg)were randomly assigned to three groups of treatments with 5 rams in each group.The experimental treatments were:(1)group A:adding 0.45%sodium bicarbonate in TMR;(2)group B:adding 0.3%probiotics in TMR,with no sodium bicarbonate;(3)group C:adding 0.5%probiotics in TMR,with no sodium bicarbonate.The adaptation period was 15 days and the sampling period was 45 days.During the experiment period,each sheep was penned individually and has free access to clean water.Results show that:(1)There was no significant difference in dry matter intake between groups(P>0.05);however,body weights at the end of the experiment was significantly different(P<0.01),with the highest and lowest final weights were observed in group C and in group A,respectively;Sheep in group C had significantly higher average daily body weight gain when compared to that in groups A(P<0.05);Consequently,feed to weight ratio for animals in group A was significantly higher than that for animals in group C.The results indicated that under the current conditions,addition of probiotics to the fattening sheep total mixed diets resulted in better growth performance than addition of sodium bicarbonate.(2)The rumen pH in group C was significantly higher than that in group A(P<0.05),but rumen pH in group A,B and C were all in normal range;the concentration of NH3-N in group A was significantly higher than that in group B and C(P<0.05);the concentration of volatile fatty acids(VFA),acetic acid,acetic acid/propionic acid and total volatile fatty acids were significantly higher in group C than those in group A and B(P<0.01),and the concentration of propionic acid in group C was significantly higher than that in group A(P<0.05).It is indicated that under the current conditions,rumen fermentation performance with total mixed diets added with probiotics is better than that of adding with sodium bicarbonate.(3)The total amount of rumen bacteria was the highest in group C.At Ph ylum level,Firmicutes,Bacteroidetes and Proteobacteria was the dominant bacte ria categories,which were significantly different between treatments(P<0.01);F irmicutes concentration was lower in group B and C than that in group A;ru men concentration of Bacteroidetes can be sequenced as B>A>C;Proteobacte ria had the highest concentration in group C.At genus level,the dominant bac teria were Prevotella,which was significantly different between groups with the highest concentration was observed in group C;total abundance of Succinivibr ionaceae_UCG-001 was significantly higher in group C than that in group A a nd B(P<0.05).The results showed that feeding probiotics could increase the c ontent of beneficial microorganisms in rumen,increase the content of lactic aci d-utilizing bacteria,and competitively inhibit the content of lactic acid-producin g bacteria,so as to effectively prevent rumen acidosis.The general conclusion of this study is:under the condition of this study,adding microecological preparation to the whole mixed diet of fattening sheep can increase the content and population structure of beneficial microorganisms in rumen,improve rumen fermentation,and improve the weight-gain performa nce of fattening sheep. |
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