The Physi-chemical Treatment Of Corn Straw And Its Application In Hu Sheep Production

At present,animal husbandry of our country is in rapid development stage,the shortage of feed and food resource restricts the development of animal husbandry economy,Crop straw is a renewable resource,it has profound significance to develop and utilize straw.In this study,the physical and chemical treatment are combined to improve the nutrition value of straw and study its effect on rumen internal environment and production performance on sheep.The results are as follow,(1)The two-factor experiment dasign was adopted to study the effects of pressure(1.5,2.0,2.5 MPa)and Ca O levels(0%,2%,4%,6%,w/w)on straw composiotion.The result showed that different explosion pressure had no significant effect on cellulose content(P>0.05),but the hemicellulose was degraded significantly with the increase of pressure level(P<0.05).The lignin content of 2.5 MPa treatment group was significant lower than that in the other groups(P<0.05).6%Ca O level treatment significantly decreased the cellulose content of corn straw(P<0.05);however,the hemicellulose content in the groups with Ca O addition were higher than the group without Ca O addition(P<0.05).(2)Rumen fistulas were installed on five healthy 5-month-old Hu sheep with similar physical traits before experiment,two-factor experiment design was adopted to study the effects of pressure(1.5,2.0,2.5 MPa)and Ca O levels(0%,2%,4%,6%,w/w)on straw rumen degradation rate,each group had three repetitions.The results showed that 1.5 MPa pressure exploded treatment group was significantly higher than2.0 MPa and 2.5 MPa treatment group for NDF and ADF rumen degradation rate of corn straw(P<0.05).Effect of 4% Ca O addition group on corn straw NDF rumen degradation rate was significantly higher than the control group and 6% Ca O addition group(P<0.05).The difference of 2% Ca O addition and 4% Ca O addition group was not significant(P>0.05),and 2% and 4% was the optimal addition level.1.5 MPa with 2% Ca O treated corn straw and 1.5 MPa with 4% Ca O treated corn straw were carried out for rumen degradation rate of dynamic experiment.Results showed that adding 2% and 4% Ca O with explosion could significantly improve the rumen effective degradation rates of DM,NDF and ADF of straw.The NDF effectivedegradation rate of straw treated by 4%Ca O and 1.5 MPa explosion was significantly higher than 2%Ca O and 1.5 MPa pressure exploded treatment group(P < 0.05).1.5MPa explosion and 4%Ca O treatment is more advantageous for the degradation of straw in sheep rumen.(3)Four sheep with rumen fistula were selected for Latin square experiment to study the effect of different straw on sheep rumen environment.The experiment was divided into four groups,control group was fed with corn stover instead of 50% silage,the treatment group was fed with 20%,50% and 75% treated straw instead of silage,respectively.The results showed that the addition of treated straw instead of silage had no significant effect on the main biochemical indexes of sheep(P> 0.05).The activity of AST in 25% treated with straw instead of silage was significantly higher than that of 50% replacement group and control group(P<0.05).The rumen acetic acid level of sheep treated with 50% physicochemical treatment of straw instead of silage was significantly higher than that of other groups(P<0.05);Propionic acid content in three straw add group were significantly higher than that of control group(P< 0.05);the content of butyric acid in 50% treated straw instead of silage group was significantly higher than that in control group(P <0.05);the content of ammonia nitrogen in rumen fluid of sheep treated with 50% instead of silage was significantly higher than that of other groups(P<0.05).50% of the treatment straw instead of silage is more conducive for the formation of volatile fatty acids and ammonia nitrogen,it is the most appropriate level of substitution.The addition of different straws and levels did not have regular effects on the rumen microbial flora species.(4)A total of 48 healthy and physiologically similar Hu sheep were randomly divided into two treatments,each with 4 replicates and 6 sheep.The control group was fed with 20% untreated straw in the diet,the treatment group was fed with 20%treated straw in the diet.The results showed that in the early stage,the feed intake and average daily gain of the sheep in test group were significantly higher than those of the control group(P<0.05),and the feed conversion rate was significantly lower than that of the control group(P<0.05),showing good production performance.However,there was no significant difference in the main indexes of sheep production performance in the whole stage(P> 0.05);In the early stage of the test,digestibility of dry matter,organic matter,crude protein and calcium in the straw group was significantly higher than that in the experimental group(P<0.05).But in the late feeding period,except crude fat digestibility,nutritient digestibility in control groupwere significantly higher than experimental group(P< 0.05).Pretreated straw significantly increased the levels of T-GSH and GSH in sheep’s serum(P<0.05),and it also could improve sheep’s immunity and antioxidant capacity.Throughout the test period,treated straw significantly enhanced the number of lactic acid bacteria and aerobic bacteria in the gastrointestinal tract,and the treated straw was more beneficial for the gastrointestinal health of the sheep.