Mixed Fungal Fermented Straw And Its Effects On Nutrient Digestion And Rumen Fermentation Of Sheep

In this experiment,corn stalks were used as research objectsand were fermented by using two mixed fungi of Phanerochaete chrysosporium and Trichoderma koningiopsis as fermenting fungi.The actual effects of the mixed fungal fermented straw,unfermented straw and mixed fungi fermentation straw in sheep production was compared.The effects of mixed fungal fermentation straw on rumen fermentation and apparent digestibility in sheep were discussed.It can provides a theoretical basis for the promotion and utilization of lignocellulose degrading fungi fermented straw feed in animal husbandry.The research content and results are as follows:(1)To determine the effect of mixed fungal fermentation on the degradation rate of corn stalk lignocellulose and the optimal fermentation conditions.Single factor experiment was used to study the effects of the proportion of fungi species(Trichoderma koningiopsis: Phanerochaete chrysosporium),inoculation amount,nutrient solution addition and fermentation days on the degradation rate of cellulose and lignin.On the basis of this experiment,the effects of various factors and their interactions on the degradation of cellulose and lignin were further evaluated by response surface method.The quadratic polynomial mathematical model of degradation of cellulose and lignin from corn straw by mixed fungus fermentation was established by using Design expert 8.0.6 software.The results show that optimum technological parameters of mixed fungus fermentation of corn straw were as follows: ratio of strain 1: 4.1,inoculation amount25.2%,nutrient solution 72.2%,and fermentation days 11 days.On this condition,the degradation rate of cellulose and lignin were reached 36.80% and 28.87%.(2)In order to explore the proportion of suitable mixed fungal fermented straw in the feeding experiment,the effects of different proportions of mixed fungal fermentation straws on the rumen fermentation parameters in vitro were studied by in vitro rumen fermentation.The results show that when the proportion of mixed fungal was 50%,75% and 100% in fermented straw,the in vitro fermentation achieved better effects;meanwhile,the gas production,NH3-N,acetic acid,propionic acid and total volatile fatty acetic(TVFA)concentrations were significantly higher(P<0.05)than unfermented straw.(3)The feeding experiment was carried out using a 3×3 Latin square test design.Six sheep with permanent rumen fistula were randomly divided into three treatments: unfermented straw group(Control,A),mixed fungal fermentation straw group(Test 1,B)and mixed fungi fermentation straw group(Test 2,C).Animals were fed unfermented corn stover,50% mixed fungal fermentation straw,and 50% mixed fungi fermentation straw,respectively.The trial was divided into three phases,each of which was 15 days,including a pre-test period of 10 days anda formal period of 5 days.The effects of apparent digestibility,blood biochemical parameters and rumen fermentation index in sheep fed different straw feeds were determined.The results are as follows: 1)the apparent digestibility of DM,CP,NDF and ADF in B and C group was significantly higher(P<0.05)than in A group;meanwhile,the apparent digestibility of ADF in B group was significantly higher(P<0.05)than that in C group.2)the content of blood urea nitrogen(BUN)in C group was significantly lower(P<0.05)than the A group;the content of glucose(GLU)in B and C group was significantly higher(P<0.05)than that of A group.3)The rumen NH3-N concentration of B group was significantly higher(P<0.05)than that of A group at3 h,and there was no significant difference between the C group and the other two groups(P>0.05).At 6 h,the content of TVFA in B group was significantly higher(P<0.05)than the other two groups,and there was no significant difference between the experimental group C and A(P>0.05);the ratio of acetic acid and propionic acid in C group was significantly lower(P<0.05)than the other two groups,and the difference between the B and A group was not significant(P>0.05).(4)The nylon bag method was used to determine the degradation rate of DM,NDF and ADF at different time points of unfermented straw and two kinds of fermented straw in rumen of sheep.The results showed that the degradation rate of DM at each time point of B and C group was significantly higher(P<0.05)than that of A group.The degradation rate of NDF at 48 and 72 h in B and C group was significantly higher(P<0.05)than that of A group.The degradation rate of ADF at 12,24,48,and 72 h in B and C group was significantly higher(P<0.05)than that in A group,and the degradation rate of ADF at 24,48,and 72 h in B group was significant higher(P<0.05)than C group.The degradation rate of DM in B and C group was significantly higher(P<0.05)than that in A group.The degradation rates of NDF and ADF in B group were significantly higher(P<0.05)than the other two groups.In conclusion,compared with the unfermented corn stover,the fermented corn stover supplemented with mixed fungi can contribute to rumen fermentation,promote digestion and metabolism,and improve the apparent digestibility of fibers and crude protein in sheep,as well as enhance the feeding effect.