Effects Of Different Proportions Of Cereal Grass And Corn Stover On Nutrient Degradation Rate, Microflora And Fattening Effect Of Beef Cattle

Simmental crossbred bull was used as experimental animals,by nylon bag method,high-throughput gene sequencing technology and feeding experiments,to investigate the effect of different ratios of millet straw and corn stover on ruminal degradability,rumen microbial flora and fattening performance,to provide a theoretical basis for use of millet straw in the beef cattle.Experiment1: This Experiment was to investigate the effects of different ratios of millet straw and corn stover on the ruminal degradability of Simmental crossbred steer.Three healthy Simmental crossbred steers of three weeks(400 ± 40 kg)with permanent rumen cannulae were used.The same concentrates supplemen in the diet,the roughage forage were A samples(100%millet straw),B samples(50% millet straw + 50% corn stover)and C samples(corn stover 100%),According to the 3 × 3 Latin square design,each period is 10 days,the pre-feeding period is 7 days,and the formal period is 3 days.Samples of roughage were weighed and placed in nylon bags.The method of “simultaneous input and removal at different time points” was used to measure the ruminal degradability of 6,12,24,36,48,and 72 h of roughage,and the effective degradability was calculated.The results showed:(1)the DM(Dry Matter,DM)ruminal degradability of samples B were significantly higher than that of A and C samples at 12 ～ 24 h(P<0.05);the DM ruminal degradability of samples B were higher than that of A samples at 72 h(P<0.05).(2)At 6 ～ 24 h,the CP(crude protein,CP)ruminal degradability of samples B were significantly higher than that A and C samples(P<0.05),and the CP ruminal degradability of A samples were significantly higher than that of C samples(P<0.05);CP ruminal degradability of A and Bsamples were significantly higher than that of C samples at 36～72 h(P<0.05);The CP effective degradability of samples A were significantly higher than that of B and C samples(P<0.05),and the effective degradability of CP of B samples was significantly higher than that of C samples(P<0.05).(3)The ruminal degradability of NDF(Neutral Detergent Fiber,NDF)of samples C were significantly higher than that of samples A at 24 and 72 h(P<0.05).(4)The ruminal degradability of ADF(Acid detergent fiber,ADF)in samples C was significantly higher than that of samples A and B at 6h(P<0.05),and the ruminal degradability of ADF in samples B were significantly higher than that of samples A(P<0.05);The ADF ruminal degradability of B and C samples were significantly higher than that of A samples at 24 h;At 48 ～ 72 h,the ADF ruminal degradability of samples C was significantly higher than that of samples A(P<0.05).Conclusion: The ruminal degradability of DM and CP of 50% millet straw + 50% corn stover were higher than those of groups and the ruminal degradability of NDF and ADF of corn stover is highest.Experiment 2: was to study the effects of rumen microbial flora of different ratios of millet straw and corn stover on the Simmental crossbred steers.Experiment design and animal management were same as Experiment 1.the roughage forage were A theatments(100% millet straw),B theatments(corn stover),C theatments(50% millet straw + 50% corn stover),respectively.At 6,12,24,36,48,and 72 h,after morning feeding on the first day of the trial period,10 ml of ruminal fluid was collected by pipette and stored at-80 ℃,to analyzed of flora changes by high-throughput gene sequencing.The results showed:(1)Bacteria: At the phylum level,Bacteroidetes,Firmicutes,Proteobacteria,and Verrucomicrobia were the dominant phylumsin 3 treatments.At the genus level,Prevotella,Caryophanon,Planococcaceae＿incertae＿sedis and Intestinimonas were the dominant bacteria in the three treatments.The number of Prevotella in treatments A at 6 and 72 h were significantly higher than that at 24 h(P<0.05);the number of Planococcaceae incertae sedis in treatments C at 24 h were significantly higher than that at6 h(P<0.05);the number of Intestinimonas in treatments B at 6 h were significantly higher than that at 24 h(P<0.05).(2)Fungi: At the phylum level,Ascomycota and Basidiomycota were dominant bacteria in the 3 treatments,and the number of Basidiomycota in the B treatments was significantly higher than that C treatments at12 h(P<0.05).At the genus level,the Thelebolus,Cladosporium,and Meyerozyma were the dominant flora;at 12 to 36 h,the numbers of Meyerozyma B and C treatments were significantly higher than that A treatments(P<0.05).At 48 h,the number of Meyerozyma in the C treatments were significantly higher than A treatments(P<0.05);At 48 h,the number of Meyerozyma of B treatments were significantly higher than A treatments(P<0.05);Conclusion: At the genus level,the number of Prevotella,Planococcaceae＿incertae＿sedis,and Intestinimonas spp.Changed significantly at different time points in the same treatments.At the level of phylum and genus,corn stover increased the number of Basidiomycota at 12 h and the number of Meyerozyma was the largest at different time points(except 48 h).Experiment 3: The Experiment was to investigate the effects of the average daily gain,average daily feed intake and feed-to-gaint ratio of different ratios of millet straw and corn stover on Simmental crossbred bull.Thirty healthy bulls(370 ± 12kg)were randomly divided into 3 groups with 10 heads in each group.Each group had the same concentrate supplement andconcentrate-roughage ratio.The roughage was 100% millet straw in group A,50% millet straw + 50% corn stover in group B,and100% corn stover in group C,with ad libitum feeding and the trial period of 60 days.The result showed:(1)The average daily gain of groups A and B were significantly higher than that of group C(P<0.05).(2)The average daily feed intake of group C was significantly higher than that of groups A and B(P<0.05),and the average daily feed intake of group B was significantly higher than that of group A(P<0.05).(3)Feed to gain ratio of group C were significantly higher than that of groups A and B(P<0.05).(4)Group A has the highest economic benefits,groups B is in the middle,and group C is the lowest.Conclusion: The millet straw has the highest average daily gain,the corn stover group has the largest of the average daily feed intake and feed-to-gaint ratio,and the millet straw has the highest economic benefits.