The Effects Of White Rot Fungus Pretreatment On Corn Straw Fiber Degradation And Feeding Value Of Sheep

This experiment explored the effect of corn straw of white rot fungi fermentation on absorption and utilization of sheep accrding to study different white rot fungi and fermentation time to the change of fiber degradation and nutrient composition.Experiment 1:The effect of white rot fungus fermentation corn straw on fiber structure,nutrient composition and enzyme activity.Experiment 2:The effect of white rot fungus fermentation corn straw on in vitro fermentation.Experiment 3:The effect of L.edodes fermented corn straw on growth performance,the nutrient digestibility and meat quality of sheep.The research results are as follows:Experiment one:There were 6 treatments in this test,namely the control group and 5 white rot fungus groups.Pleurotus ostreatusy Lentinus edodes,Hericium erinaceus,Pleurotus eryngii and Flammulina filiformis,were used to ferment corn stalks.The stems,leaves and sheaths of cron straw samples were collected at 0,21 and 35 days of fermentation for electron microscope scanning to analyze the changes of corn straw and the status of white rot fungus mycelium on the straw during the fermentation process.Samples of fermentation 0,14,21,28 and 35 days were used for nutrients and enzymes activity The experimental results show that:from the electron microscope scanning analysis,it could be concluded that different white rot fungi damage the fiber structure in corn straws roughly.With the extension of fermentation time,the fiber structure of corn straw was destroyed more seriously,which is more beneficial to cellulase Hydrolysis progresses.The damaged parts of straw were covered by mycelium preferentially,so the sheath and leaves of straw appeared cracks,and even break into fragments before the bark.White rot fungus fermentation could significantly increase the crude protein content(P=0.028),the ability of different strains to increase the crude protein content of straw follows the following sequence:P.ostreatus>L.edodes>F.filiformis>P.eryngii>L.erinaceus.It was more obvious that white rot fungi could significantly reduce the lignin content in the straw,but at the same time it would also significantly cause the loss of cellulose(P<0.001).In addition,the changes in enzyme activity in the five treatment groups were consistent.The activity of lignin degrading enzyme(lignin peroxidases,manganese perxidases and laccase)and cellulose degrading enzyme(carboxymenthel cellulas and filterpaper cellulose)increased with the extension of fermentation time,and the latter reached its maximum value on the 28th day of fermentation.Combined with the selectivity of white rot fungi,the ratio of lignin to cellulose loss,L.edodes and P.eryngii were superior to other white rot fungi in selecting lignin.Experiment two:Carry out the in vitro fermentation test on the basis of the design of test one.The experimental results show that:although the prolongation of fermentation time would reduce the in vitro dry matter digestibility,the concentration of total volatile fatty acids,total gas production and methane production of fermented corn straw(P<0.001),but compared with the control group,P.ostreatus,L.edodes,H.erinaceus and P.eryngii could improve the rumen fermentation capacity,especially L.edodes.On the 28th day of fermentation,the total gas production could reach the maximum.The in vitro dry matter digestibility increased before 21 days of fermentation and decreased significantly after 28 days of fermentation,and P.ostreatus reached its highest value(68.24%)at 21 days of fermentation among all strains.In addition,the prolonged fermentation time of white rot fungi would significantly reduce the methane production of corn straw in vitro fermentation,and all treatments have the most obvious reduction effect after 28 days of fermentation.Experiment three:16 Ujimqin sheeps were randomly divided into two treatments(control group and fungus group),each treatment was repeated 8 times,the control group was fed with ordinary air-dried corn straws,and the fungus group was fed with corn straws of L.edodes fermentated.The experiment period was 70 days,including the pre-feeding period of 14 days and the formal period of 56 days.Two 5-day metabolic experiments were conducted on the 4th and 8th weeks of the formal period,blood was collected for blood biochemical analysis and the body weight of sheep was recorded for calculation of average daily gain every two weeks.After the experiment,all the sheep were slaughtered,then,the longest back muscles and semimembranosus were collected to determinate meat quality and myosin heavy chain(MyHC)gene.The experimental results show that:L.edodes fermented corn straw could significantly increase the average daily gain(P<0.01),dry matter(P<0.01),crude protein(P<0.01),crude fat(P<0.01)and acid detergent fiber(P<0.01)apparent digestibility of sheep.Therefore,the total protein and albumin content in the product also increased.Moreover,although L.edodes fermentation has no effect on intermuscular fat and pH24,it could significantly increase the a*and b*,and reduce the L*of the longest back muscles and leg muscles(P<0.01).From the analysis of MyHC,it was found that L.edodes fermentation can increase the composition ratio of oxidized muscle fibers(MyHC-? and MyHC-??)in the longest back muscles and leg muscles,which helps to improve meat quality.In summary,due to L.edodes and P.eryngii have high selectivity for the degradation of lignin and cellulose,they could improve the nutritional value of corn straw,and also increase the rumen fermentation capacity.The animal experiment of feeding corn straw with L.edodes fermented sheep found that white rot fungus fermentation could help improve growth performance,the nutritional digestion and meat quality of sheep.