Effects Of Fermented Mixed Meals To Replace Soybean Meal And Small Peptide Products Supplementation In Diets On Growth Performance,Nutrient Digestion,Rumen Fermentation And Bacterial Composition Of Beef Cattle

The purpose of this study was to evaluate the effects of solid-state fermentation of compound bacteria on nutritional value of mixed meal?rapeseed meal: cottonseed meal = 1:1?,and to investigate the effects of different levels of fermented mixed meals to replace soybean meal and small peptide products supplementation in diets on growth performance,nutrient apparent digestibility,rumen fermentation parameters and bacterial diversity of beef cattle.Finally,it was conducted to provide basic data for the rational use of cottonseed and rapeseed meal,and provide a theoretical basis for the development and efficient use of low-cost feed resources for beef cattle.Trial 1: Effects of solid-state fermentation of compound bacteria on nutritional value of mixed meal.Currently shortage of protein feed sources was a major problem for animal and feed industry in China.To alter this situation and improve the utilization efficiency of inferior protein raw materials,cottonseed and rapeseed meal,two alternative protein sources with greater amount of production and lower price in China,were used as raw materials,and mixed at a ratio of 1:1 as fermentation substrates,and solid-state fermented by strains of Aspergillus Niger,Aspergillus Oryzae and Bacillus Subtilis.Analyze the changes of nutritional components,amino acids,enzyme activity,the content of anti-nutritional factors and mycotoxins before and after fermentation,and explore the improvement effect of microbial solid-state fermentation on the nutritional value of mixed meal.The results showed that:?1?Compared with before fermentation,the content of crude protein?CP?,Ash,calcium?Ca?,and phosphorus?P?in after fermentation was significantly increased?P<0.05?,and the neutral detergent fiber?NDF?was significantly reduced?P<0.05?,there was no significant different in dry matter?DM?,acid detergent fiber?ADF?and total energy?GE??P>0.05?.?2?In term of amino acids composition,compared with before fermentation,except for glutamic acid,the remaining amino acid content and total amino acids?TAA?,essential amino acids?EAA?,non-essential amino acids?NEAA?increased significantly?P<0.05?.?3?The content of aflatoxin B1?ABF1?,zearalenone?ZEN?,free gossypol,tannin,and phytic acid of after fermentation were lower than that of before fermentation?P<0.001?.?4?The protease activity of after fermentation was significantly higher than that of before fermentation?P<0.001?,the lipase activity had a high tendency than that of before fermentation?P=0.083?,and the amylase activity was not found significant difference?P>0.05?.It is concluded that the nutritional composition,the content of amino acid and protease activity of the solid-state fermented mixed meals with compound bacteria were significantly improved,and the content of mycotoxins and anti-nutritional factor were significantly reduced.Trial 2: Effects of fermented mixed meal to replace soybean meal in diets on growth performance,nutrient apparent digestibility,rumen fermentation parameters and bacterial composition of beef cattle.This experiment was to investigate the effects of different proportions of fermented mixed meal to replace soybean meal in diets on growth performance,nutrient apparent digestibility,rumen fermentation parameters and bacterial composition of beef cattle.Thirty-five healthy Simmental crossbred cattle with an initial body weight of?480.71±45.65?kg were randomly divided into 5 groups,with 7 cattle in each group,and were fed total mixed rations diet with fermented mixed meal to replace soybean meal levels with 0,25%,50%,75%,and 100%,respectively.The experiment lasted for 85 d,with 25 d of adaptation period and 60 d of trial period.The results showed as follows:?1?In terms of growth performance,the averages daily gain?ADG?and feed/gain?F/G?of beef cattle were significantly changed by fermented mixed meal instead of soybean meal?P<0.05?,and the ADG had a tendency of quadratic curve?P=0.096?,IV group had the highest ADG and the lowest F/G?P<0.05?.?2?In terms of nutrients apparent digestibility,as the replacement ratio of fermented mixed meal increasing,the apparent digestibility of organic matter?OM?,CP,NDF,and ADF showed a quadratic curve?P<0.05?,and there was no significant difference in the apparent digestibility of P and Ca?P>0.05?.?3?The content of urea nitrogen?UN?and alkaline phosphatase?ALP?in the serum decreased linearly with the increase of the replacement ratio?P>0.05?,and the content of total cholesterol?T-CHO?showed a tendency decreased linearly?P=0.098?.?4?In terms of rumen fermentation products,the content of ammonia nitrogen?NH3-N?and molar ratio of butyrate decreased linearly with the increase of replacement ratio of fermented mixed meal?P<0.05?,and the molar ratio of propionate and the value of acetate: propionate showed quadratic curve?P<0.05?.?5?In terms of rumen flora composition,replacement of soybean meal with fermented mixed meal had no significant effect on rumen bacteria richness and diversity in beef cattle?P>0.05?.At the phylum level,Bacteroidetes,Firmicutes,and Proteobacteria were the dominant phylum,and with the replacement ratio of fermented mixed meal increasing,the relative abundance of Proteobacteria presented quadratic curve?P>0.05?,and the relative abundance of Firmicutes had a tendency decreased linearly?P=0.082?.At the genus level,the dominant genus was Prevotella₁,the fermented mixed meal to replace soybean meal had an impact on the relative abundance of norank_fBacteroidales_S24-7_group,Prevotella₉ and Succinivibrionaceae_UCG-002 in rumen?P<0.05?,and the relative abundance of norank_fBacteroidales_S24-7_group was positively correlated with the molar ratio of isovalerate?r=0.441,P=0.027?,and the relative abundance of Prevotella₉ was negatively correlation with the molar ratio of isobutyrate?r=-0.475,P=0.016?.With the replacement ratio increasing,the relative abundance of Christensenellaceae_R7_group had a tendency decreased linearly?P=0.078?;the relative abundance of Prevotellaceae_UCG-004 showed a tendency of quadratic curve?P=0.099?,and was negatively correlation with the content of NH3-N?r=-0.581,P=0.002?,and the relative abundance of Succinivibrio presented a tendency quadratic curve?P=0.072?,and was positively correlation with total volatile fatty acids?T-VFA??r=0.541,P=0.005?.?6?In terms of economic benefits,compared with Group I,the feed costs in Group 25%,50%,75%,and 100% were reduced by 0.76%,1.49%,2.21%,and 2.99%,respectively;and the average profit per head increased by 35.91%,44.07% and 10.94%,respectively.In summary,the replacement of 100% soybean meal in diets with fermented mixed meals could improve the utilization efficiency of protein and had no significant negative impact on ADG,F/G and economic benefits,and the growth performance and economic benefit of beef cattle were higher when the replacement ratio was 75%.Trial 3: Effects of small peptide products supplementation in diets with fermented mixed meals on growth performance,nutrient apparent digestibility,rumen fermentation parameters and bacterial composition of beef cattle.In order to improve the feeding effect of fermented mixed meals,this study added different levels of small peptide products in diets which used fermented mixed meals to replace 100% soybean meal,and explored the optimal levels of small peptide products supplementation in diets with fermented mixed meals through the growth performance,nutrient apparent digestibility,rumen fermentation parameters and bacterial composition of beef cattle.Single factor trial design was adopted: twenty-eight healthy Simmental crossbred cattle?481.43±36.36 kg of initial weight?were randomly assigned to four treatments,each treatment had 7 replicates,with 1 cattle in each replicate,and were fed total mixed rations diet with small peptide products supplementation levels with 0,0.5%,1.0%,and 1.5% respectively.The pre-test period lasted for 25 days and the trial lasted for 60 days.The results showed as follows:?1?In terms of growth performance,with the increase of dietary small peptide products levels,the ADG presented a tendency quadratic curve?P=0.062?,and the F/G showed a quadratic curve?P<0.05?,Group ? had the highest ADG and the lowest F/G.?2?In terms of nutrients apparent digestibility,the apparent digestibility of OM had a quadratic curve with the increase of the levels of small peptide products?P<0.05?;and the apparent digestibility of CP of III group was significantly higher than that of 1.5% group?P<0.05?,and it showed a tendency of quadratic curve?P=0.087?.?3?In the terms of serum biochemical indicators,with the increase of dietary small peptide products levels,the activity of ALT,AST and the content of UN were increased in a quadratic curve?P<0.05?,and the content of T-CHO and GLU presented a tendency of difference?P=0.096,P=0.055?.?4?In terms of rumen fermentation parameters,with the increase of dietary small peptide products levels,the molar ratio of acetate and the value of acetate: propionate decreased first and then increased,showed a quadratic curve?P<0.05?,and the molar ratio of isovalerate decreased linearly?P<0.05?.?5?In terms of rumen flora composition,with the increase of dietary small peptide products levels,the Ace index and Chao index changed in a quadratic curve?P<0.05?.From the level of phylum for rumen bacterial flora,the dominant phylum in each group were Bacteroidetes,Firmicutes,and Proteobacteria,and with the increase of dietary small peptide products levels,the relative abundance of Firmicutes,Tenericutes and Saccharibacteria presented a tendency quadratic curve?P<0.10?;From the level of genus for rumen bacterial flora,the relative abundance of Prevotella₁ was over 25%,which was the dominant genus,and with the level of small peptide products increasing,the relative abundance of Prevotella₁ had a tendency quadratic curve?P=0.089?,the relative abundance of Rikenellaceae_RC9_gut_group showed a quadratic curve?P<0.05?,which was negatively correlation with propionate?r=-0.489,P=0.029?and valerate?r=-0.529,P=0.016?;the relative abundance of Christensenellaceae_R-7_group of 0.5% group was significantly higher than that of other groups?P<0.05?,and was positively correlation with acetate?r=0.678,P=0.001?,butyrate?r=0.481,P=0.032?and acetate: propionate?r=0.729,P<0.001?;the relative abundance of Ruminococcaceae_UCG-014 was significantly higher than the other groups?P<0.05?.?6?In terms of economic benefits,compared with Group I,the average profit per cattle of 0.5% and 1.0% groups increased by 8.86% and 27.07%,while Group1.5% decreased by 41.77%.In conclusion,under the conditions of this experiment,the addition 0.5% to 1.0% of small peptide products to dietary with fermented mixed meals significantly affected microbial richness in the rumen and the level of phylum and genus of microorganisms,affected the rumen fermentation parameters,and improved nutrient digestibility,finally improved the growth performance of beef cattle.