| In ruminant diets,roughage usually accounts for 40%-70%or more,which is an important source of nutrition for ruminants.However,roughage is difficult to digest and has poor palatability.It is of great significance to process roughage to improve its palatability,so as to enhance the digestion and absorption capacity of ruminants to roughage and improve their meat quality.In this experiment,using cellulase and bacteria(Yeast,Bacillus and Lactobacillus)as treatment agents,buckwheat straw,straw and alfalfa hay were selected as roughage.The effects of enzyme bacteria mixed treatment of buckwheat straw,straw and alfalfa hay on their nutrient composition,fermentation quality and fiber structure,as well as on growth performance,slaughter performance,meat quality,blood biochemical indexes,rumen fermentation parameters and rumen bacteria of Tan sheep were studied in six experiments.In this way,we can systematically study the mechanism of this treatment on improving the utilization rate of roughage,in order to provide more methods for roughage treatment,improve the palatability of roughage,and provide technical means and theoretical basis for improving the growth performance and meat quality of Tan sheep.Experiment 1 Effects of enzyme bacteria mixed treatment of roughage on its nutrient composition and fermentation qualityThe experiment was divided into five groups,the control group was untreated buckwheat straw,straw and alfalfa hay,the experiment group ? was treated with cellulase alone(enzyme activity? 10000U g),the experiment group ? was treated with bacteria alone,and the experiment group ? was treated with mixed enzyme and bacteria(the ratio of enzyme to bacteria was 8:15),the experiment group IV was treated with mixed enzyme and bacteria(the ratio of enzyme to bacteria was 8:20),and the experiment group ? was treated with mixed enzyme and bacteria(the ratio of enzyme to bacteria was 8:25).After 30 days of fermentation,the nutritional components and fermentation quality were detected,with 3 replicates in each group.After 30 days of fermentation,the nutritional components and fermentation quality of buckwheat straw,straw and alfalfa hay were detected,with 3 replicates in each group.The results showed that the neutral detergent fiber and acid detergent fiber of buckwheat straw,straw and alfalfa hay with enzyme bacteria ratio of 8:20 were significantly lower than those of the control group(P<0.01),and the number of Yeast and Bacillus in buckwheat straw,straw and alfalfa hay fermented with the ratio of 8:20 was the most,the number of mold was the least,and the total number of colonies was in the middle,which inhibited the production of aflatoxin B1.The results showed that the optimal ratio of enzyme bacteria was 8:20.Experiment 2 Effects of enzyme bacteria mixed treatment of roughage on its fiber structureAccording to experiment 1,the fiber structure of each group was observed by scanning electron microscope after 30 days of fermentation.The samples of buckwheat straw,straw,alfalfa hay leaf and alfalfa hay stem were observed with scanning electron microscope(three replicates in each group).The results showed that the fiber structure of buckwheat straw,rice straw and alfalfa hay in each experimental group was destroyed compared with the control group.The order of damage degree from big to small is:Experiment group IV>Experiment group V>Experiment group III>Experiment group ?>Experiment group I>control group.The best ratio of enzyme to bacteria is 8:20,because it is the most destructive.Experiment 3 Effects of enzyme bacteria mixed treatment of roughage on rumen fermentation parameters and diversity of bacteria in Tan sheepForty 3-month-old Tan sheep with similar body weight and good health were randomly divided into 4 groups with 10 in each group.Control group ? was fed with basal diet+untreated buckwheat straw and alfalfa hay(the ratio of buckwheat straw to alfalfa was 20:80),and experimental group I was fed with basal diet+buckwheat straw and alfalfa hay(the ratio of buckwheat straw to alfalfa hay was 20:80)treated with cellulase(enzyme activity? 10000U/g)+bacteria(the ratio of enzyme to bacteria was 8:20).The control group II was fed with basal diet+untreated straw and alfalfa hay(the ratio of straw to alfalfa was 60:40),and the experimental group ? was fed with basal diet+rice straw and alfalfa hay(the ratio of straw to alfalfa hay was 60:40)treated with cellulase(enzyme activity? 10000U/g)+bacteria treatment(he ratio of enzyme to bacteria was 8:20).The pre-feeding period was 15 days and the normal feeding period was 60 days.1)On the end of feeding experiment,rumen fluid was collected from fasting oral cavity,and then sub packed and stored to determine rumen pH value,ammonia nitrogen concentration and volatile fatty acid concentration.The results showed that this treatment could significantly reduce the concentration of pentanoic acid in the rumen of Tan sheep(P<0.05),and improve the rumen pH value,ammonia nitrogen concentration and the concentration of volatile acids such as acetic acid,propionic acid,butyric acid,isobutyric acid and isovaleric acid to a certain extent,but the difference was not significant(P>0.05).2)DNA was extracted from rumen fluid for rumen bacterial diversity analysis.The results showed that this treatment increased the number of OTU and changed the diversity of bacteria in Tan sheep rumen.At the level of gate,the proportion of Firmicutes in the rumen of Tan sheep was increased,and the number of Bacteroides,Kiritimatiellaeota and Cyanobacteria were reduced.At the genus level,this treatment increased the number of Prevotella,Kutella,Rumencocci NK4A214,Rumel bacillus and Sphingobacterium in the rumen of Tan sheep,and decreased the number of Christensen R7 genera.Experiment 4 Effects of enzyme bacteria mixed treatment of roughage on Functional genes and carbohydrate active enzymes of rumen bacteria in Tan SheepDNA was extracted from rumen fluid for metagenomic analysis.The results showed that this treatment had a certain effect on the functional genes and carbohydrate active enzymes of rumen bacteria in Tan sheep.The main functional enzymes in Tan sheep rumen are involved in metabolism,genetic information processing and environmental information processing.The number of genes in the three pathways of pyrimidine metabolism,amino sugar and nucleotide sugar metabolism,and glyoxylate and dicarboxylate metabolism in Tan sheep rumen were increased by this treatment(P<0.01).At the same time,GH,GT and CBM are the main CAZy in Tan sheep rumen.This treatment improved the activities of partial hemicellulose degrading enzymes and partial nonstructural carbohydrate enzymes in the rumen of Tan sheep,and promoted the digestion and absorption of roughage.Experiment 5 Effects of enzyme bacteria mixed treatment of roughage on growth performance and blood biochemical indexes of Tan sheepThe fasting vein blood was collected on the day of feeding test for blood biochemical index measurement,and then the weight of Tan sheep was taken.The results showed that the total weight gain and average daily weight gain of Tan sheep fed with enzyme bacteria mixed treatment of buckwheat straw,straw and alfalfa hay were significantly increased(P<0.01),and the feed to weight ratio was significantly decreased(P<0.01),which improved the economic benefits of Tan sheep breeding.At the same time,the content of serum total protein and serum globulin were significantly increased(P<0.05),and the content of serum urea was significantly decreased(P<0.01).Experiment 6 Effects of enzyme bacteria mixed treatment of roughage on Slaughtering performance and meat quality of Tan sheepAfter feeding experiment,5 sheep were slaughtered in each group.Their slaughter performance was tested.According to the regulations,their meat quality and nutritional composition of mutton were detected.The results showed that there were no significant differences in slaughter performance,meat quality and nutrient composition between the experimental groups and the control group(P>0.05).However,the carcass weight,slaughter rate,net meat weight and eye muscle area of experimental group ? were increased by 2.56%,2.23%,3.22%and 1.69%respectively compared with control group ?,and GR value was decreased by 8.43%compared with control group ?.The carcass weight,slaughter rate,net meat weight and eye muscle area of experimental group ? were increased by 2.95%,1.29%,2.20%and 2.58%respectively,and the GR value was decreased by 1.28%.This treatment can increase carcass weight,slaughter rate,eye muscle area and net meat weight of Tan sheep,and reduce GR value at the same time.Compared with control group ?,the water loss rate,shear force and drip loss of experiment group ? decreased by 7.25%,1.79%and 15.13%,and the cooked meat rate and meat color redness(a*)increased by 5.64%and 3.63%respectively.Compared with the control group?,the water loss rate,shear force and drip loss of experiment group ? were decreased by 4.23%,1.55%and 27.74%,respectively,and the cooked meat rate and meat color redness(a*)value of experiment group ? were increased by 6.02%and 2.86%respectively.The crude fat content of experimental group ? was 9.25%lower than that of control group ?,the crude protein content was 4.31%higher than that of control group ?,the crude fat content of experimental group ? was 3.06%lower than that of control group ?,and the crude protein content was 6.39%higher than that of control group ?.The results showed that this treatment could improve the meat performance and carcass lean percentage of Tan sheep,improve the meat color and quality,reduce the fat content and increase the protein content of Tan sheep.In conclusion,the application of enzyme bacteria mixed 8:20 to treat buckwheat straw,straw and alfalfa hay can significantly reduce the content of neutral detergent fiber and acid detergent fiber,improve the fermentation quality and destroy the fiber structure.Buckwheat straw,straw and alfalfa hay treated with enzyme bacteria can improve the weight gain,economic benefit,serum total protein content and globulin content of Tan sheep,reduce the serum urea content,improve the slaughter performance and meat quality,affect the rumen bacterial diversity and increase the number and proportion of fiber degrading bacteria in the rumen Gene abundance of functional genes and some carbohydrate enzymes.Therefore,in this experiment,the feeding effect of mixed treatment of buckwheat straw,straw and alfalfa hay with cellulase(enzyme activity?10000 U/g)and bacteria is better,which is beneficial to the healthy breeding of Tan sheep and can be popularized in production. |
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