Comparison Of Growth Performance,Microflora And Differential Metabolites Of Beef Cattle Fed Fermented Rice Straw With Beef Cattle Fed Fresh Corn Stalk

In order to evaluate the difference in feeding values between fermented rice straw and corn stalk,twenty simmental hybrid beef cattles with similar liveweight were randomly allotted to two groups on average for a 90-d epxeriment,cattles in one group fed ration based on fermented rice straw and cattles in the other group fed ration based on fresh corn stalk.All cattles were weighted on the first day and the last day,samples of Jugular vein blood,rumen fluid and feces were collected on day 30,day 60 and day 90 before feeding in the morning during experiment period.At the end of experiment,two cattles with the weight close to average body weight were slaughtered and samples were collected from rib eye,shank and tenderloin.Experiment results are described as below:1.There was no significant difference in terms of average daily gain,average levels of biochemical and rumen fermentation parameters during experiment compared cattle fed fermented rice straw as basal diet with cattle fed corn stalk as basal diet(P>0.05).Cattles fed with fermented rice straw had higher concentrate of acetic acid and propionic acid in rumen fluid on day 60 and day 90(P<0.05),higher average level of TP,ALB,TC and TG in plasma(P>0.05)and lower level of blood urea nitrogen(P>0.05)than cattle fed with corn stalk.2.Cattle fed fermented rice straw had higher bacterial abundance and diversity index(P>0.05)and lower fungal abundance and diversity index(P>0.05)than cattle fed corn stalk.Cattles fed fermented rice straw or corn stalk had the same dominant rumen bacteria of Bacteroidetes,Firmicutes and Tenericutes,cattle fed fermented rice straw had higher Bacteroidetes abundance and lower Firmicutes abundance than cattle fed corn stalk,the abundance of Bacteroidetes from 90-d rumen fluid of cattle fed fermented rice straw was significantly higher than that of cattle fed corn stover(P<0.05),but the abundance of Firmicutes in rumen fluid was significantly lower than that of cattle fed corn stover(P<0.05).Neocallimastigomycota and Ascomycota were the dominant fungi at phylum level in rumen fluid and shared by cattle fed fermented rice straw and cattle fed corn stalk.There was no significant difference in the abundance of Neocallimastigomycota or Ascomycota between cattle fed fermented rice straw and cattle fed corn stalk(P>0.05).3.Cattle fed fermented rice straw had lower abundance index and diversity index of bacteria and fungus in feces than cattle fed corn stalk(P>0.05).The dominant bacteria at phylum were Firmicutes,Bacteroidetes and Tenericutes in feces of cattle fed fermented rice straw and cattle fed corn stalk.The abundance of Firmicutes in feces on day 60 and day 90 collected from cattle fed fermented rice straw was respectively lower than cattle fed corn stalk(P>0.05),but the abundance of Bacteroidetes was higher than cattle fed corn stalk(P>0.05).The dominant fungi at phylum were Neocallimastigomycota and Ascomycota in feces of cattle fed fermented rice straw and cattle fed corn stalk,cattle fed fermented rice straw had significantly higher abundance of Ascomycota in feces on day 90 than cattle fed corn stalk(P<0.05)but had significantly lower abundance of Neocallimastigomycota in feces on day 90 than cattle fed corn stalk(P<0.05).4.Sixteen differential metabolites were screened out from rumen fluid of cattle,cattle fed fermented rice straw had significantly lower level of threonine and glutamic acid than cattle fed corn stalk(P<0.05),the levels of the other 14 differential metabolites in rumen fluid of cattle fed fermented rice straw were respectively higher than cattle fed corn stalk(P<0.05).Nine differential metabolites were found from serum of cattle,cattle fed fermented rice straw had higher levels of alpha-ketoisocaproic acid and glycerol than cattle fed corn stalk(P<0.05)and lower levels of the other seven differential metabolites than that of cattle fed corn stalk(P<0.05).5.There was no significant difference in the content of flavor amino acids in rib eye and tender lion between cattle fed fermented rice straw and cattle fed corn stalk(P>0.05),but cattle fed fermented rice straw had significantly higher stearic acid in rib eye and tender loin than cattle fed corn stalk(P<0.05).Compared with feeding with corn stalk,feeding fermented rice straw to Simmental beef cattle increased the levels of delicious amino acids(aspartic acid,glutamic acid)and sweet amino acids(alanine,glycine)of shank and decreased the contents of bitter amino acids(methionine,arginine,phenylalanine,tyrosine,tryptophan)of shank.In addition,there was no significant difference in the level of fatty acids in shank between cattle fed fermented rice straw and cattle fed corn stalk(P<0.05).