Effects Of Different Microecological Regulators On Growth Performance And Rumen Microecology Of Beef Cattle

The complex microbial community in rumen ecosystem plays an important role in gastrointestinal health of ruminants.Disturbance of rumen microecosystem seriously affects performance of animals and reduces economic benefit.Microecological regulators are believed to promote the health and growth of beef cattle by regulating the number of beneficial microorganisms in their rumen.However,the effects of different types of microecological regulators on beef cattle are still unclear.Therefore,this experiment compared the effects of three different types of microecological regulators on the growth performance and rumen microecology of beef cattle by feeding Bacillus subtilis,self-made Alginate oligosaccharides and Acremonium terricola culture,so as to provide scientific theoretical basis for improving the growth performance of beef cattle.The research methods and results are as follows:(1)In this study,alginate lysase Alg X1989 was used to prepare Alginate oligosaccharides by enzymolysis of sodium alginate,and the conditions of enzymolysis reaction and the composition of the product Alginate oligosaccharides were analyzed.The results were as follows:the optimum pH and temperature of enzymatic hydrolysis were 7.5 and25 ℃ respectively,the optimal enzyme dosage was 0.3U/m L and the minimum reaction time was 3h.The composition of Alginate oligosaccharides was detected as monosaccharides(2.31%),disaccharides(13.9%),trisaccharides(76.62%)and tetrasaccharides(7.17%)by TLC and ESI-MS analysis.(2)This experiment was conducted to investigate the effects of different types of microecological regulators on growth performance,serum biochemical indices,antioxidant and immune indices,health score and nutrient apparent digestibility of beef cattle.Forty healthy Angus beef cattle aged 7 months with an average body weight of 202.39±23.14 kg were randomly divided into four treatment groups as A,B,C and D with 10 replicates in each group.Cattle in group A were fed a basal diet,in groups B,C and D were fed the basal diet supplemented respectively with 700mg/kg Bacillus subtilis,Alginate oligosaccharides and Acremonium terricola culture.The pre-experiment lasted for 7 d,and the formal experiment lasted for 56 d.Results: In terms of growth performance,there were no significant differences in body weight and average daily dry matter intake among the four groups at all stages(P >0.05).The average daily gain in group B was significantly higher than that in groups A,C and D at the stage from 1 to 28 d(P < 0.05),and the ratio of feed to gain in group B was significantly lower than that in groups A and C(P < 0.05),but there were no significant differences in the average daily gain and the ratio of feed to gain in groups in 29-56 d and1-56d(P > 0.05).In terms of serum biochemical indexes,there were no significant differences among the four groups(P > 0.05),except the total protein content in groups C and D was significantly higher than that in group A(P < 0.05),and the globulin content in group D was significantly higher than that in group A(P < 0.05).In terms of antioxidant and immune indexes,the serum total superoxide dismutase content in groups C and D was significantly higher than that in group A(P < 0.05)and the serum immunoglobulin G content in group C was significantly higher than that in group A(P < 0.05).In terms of health score,there was no significant difference in all indexes except the eye secretion in group C was significantly lower than that in group A(P < 0.05).In terms of nutrient apparent digestibility,the crude protein apparent digestibility of beef cattle in group B was significantly higher than that in group A(P <0.05).The apparent digestibility of neutral detergent fiber and acid detergent fiber in group B was significantly higher than that in groups A and D(P < 0.05).The test results show that: Bacillus subtilis improved the growth performance of beef cattle by improved the nutrient apparent digestibility of diet,while Alginate oligosaccharides and Acremonium terricola culture promoted the health of beef cattle by improved the protein metabolism and immune antioxidant performance.(3)This experiment was conducted to study the effects of three different types of microecological regulators on rumen parameters and ruminal bacterial flora of beef cattle.The rumen fermentation indexes of four groups of cattle were determined,and the bacterial flora of four groups of cattle was analyzed by 16 S r RNA gene sequencing method.Results: Three different types of microecological regulators did not affect rumen pH of Angus cattle(P > 0.05).Compared with group A,the contents of ammonia nitrogen,acetate and propionate in rumen were increased in groups B and C,and the contents of ammonia nitrogen,acetate,propionate and butyrate in rumen were decreased in group D.All three microecological regulators reduced the diversity of rumen bacteria.At the phylum level of rumen bacteria,additives in group B and C increased the relative abundance of Bacteroidetes,and microecological regulator in group D increased the relative abundance of Firmicutes.The relative abundance of Spirochaetae in group C was significantly increased(P < 0.05).At the family level,the relative abundance of Prevotellaceae in group B was significantly increased(P < 0.05).Additive group C significantly increased the relative abundance of Ruminococcaceae and Bacteroidales＿BS11＿gut＿group(P < 0.05).Group D significantly increased the relative abundance of Lachnospiraceae(P < 0.05).The relative abundance of Bacteroidales＿S24-7＿group in group B and group C was significantly decreased(P < 0.05).At the genus level,the relative abundance of Prevotella＿1 in group B was significantly increased(P <0.05).The relative abundance of Veillonellaceae＿UCG-001 in group D was significantly increased(P < 0.05).The test results show that: Bacillus subtilis promoted rumen fermentation parameters and the growth of proteins and non-fibrous carbohydrate decomposition bacteria in rumen of beef cattle such as Bacteroidetes prevotella.Alginate oligosaccharides promoted rumen fermentation parameters and both fibrous and non-fibrous decomposition bacteria such as Spirochaetae,Bacteroidales and Ruminococcaceae.However,Acremonium terricola culture significantly increased the relative abundance of Firmicutes and Lachnospiraceae and promote the decomposition of fiber,but has a negative effect on rumen fermentation.In conclusion,three different types of microecological regulators have beneficial effects on Angus beef cattle to varying degrees.The three microecological regulators all promoted the growth of beef cattle,promoted the digestion and utilization of feed nutrients by improved the rumen microflora structure,and promoted the health of beef cattle by improved protein metabolism level and immune antioxidant performance.In terms of growth performance,Bacillus subtilis had the best effect,followed by Alginate oligosaccharides.