| The purpose of this study is to use single bacteria and mixed fungi to study the effects of different pretreatment times on the nutritional value of white tea by-products under solid-state fermentation conditions,and use in vitro and semi-in vitro tests to evaluate the effects of pretreatment products on gas production,Effects of rumen fermentation parameters and the degradation properties of nutrients in the rumen.It provides a reference for the development of white tea by-products as ruminant feed,and single/mixed fungi for improving the quality and efficiency of agricultural by-products as ruminant feed raw materials.The main research content and results are as follows.Experiment 1:Effect of pretreatment with white rot fungi on fibrous carbohydrates,other chemical components and quality index of white tea by-productsThe purpose of this experiment was to explore the morphological structure changes and nutritional value of pretreatment white by-products at different time points by using single and mixed fungi.Phanerochaete chrysosporium,Pleurotus otreatus and their co-cultivation P.chrysosporium+P.otreatus(Dual treatment group)were used to pretreat white tea by-products for 28 days under solid-state fermentation conditions.Observed by scanning electron microscope(SEM),the three fungal treatment groups all caused damage to the cell wall of white tea by-products.Among them,the P.chrysosporium treatment group had more holes,and the fracture surface was obvious.All fungal treatment groups resulted in a significant decrease in the crystallinity index of white tea by-products(P<0.01).The P.chrysosporium and Dual treatment groups significantly reduced the ADL content of white tea by-products at day 7(P<0.01).With the prolongation of pretreatment time,the three fungal treatment groups all significantly reduced the TET content of white tea by-products(P<0.01).In addition,crude protein content was significantly increased(P<0.01)in all fungal treatment groups.The feeding quality assessment indexes of RFV,RFQ,QI and GI were the highest when P.chrysosporium pretreated white tea by-products for 7 days.Experiment 2:Effect of white rot fungal pretreatment on in vitro rumen gas production,VFA and major microorganisms of white tea by-productsThe purpose of this experiment is to evaluate the feeding value of white tea by-products pretreated by white rot fungi at different time points by using in vitro fermentation experiments from a biological point of view.In terms of the measurement of gas production,the gas production of the three fungal treatment groups was significantly lower than that of the control group at 28 days(P<0.01).At 7 days,the total acid content was significantly lower in P.ostreatus and Dual treatment groups(P<0.05).The content of propionic acid in the P.chrysosporium treatment group was not significantly different from that of the control group on the 7th day,but the P.ostreatus and Dual treatment groups were significantly lower than the control group(P<0.05).The A/P ratios of the three treatment groups reached the highest on the 28th day,and the A/P ratios of the P.chrysosporium treatment group on the 7th day were significantly lower than those at other time points(P<0.01).However,the A/P of the P.chrysosporium-treated group at day 7 was significantly higher than that at other time points(P<0.01).The isobutyric acid content of P.ostreatus and Dual treatment groups showed a similar trend,and was significantly higher than other time points from the 7th day(P<0.01).The butyric acid content of the P.ostreatus and Dual treatment groups was significantly higher than that of the control group on the 7th day(P<0.05),but the P.chrysosporium treatment group was significantly lower than the control group(P<0.05),and it was the lowest on the 14th day,only 10.60 mmol/L.On day 7,the NH3-N content of the P.chrysosporium treatment group was significantly lower than that of the P.ostreatus and Dual treatment groups(P<0.05).On the 28th day,the NH3-N content of the three treatment groups was significantly higher than that of the control group(P<0.01),and there was no significant difference among the three treatment groups.The rumen microbial composition was significantly changed in all three treatment groups.R.Albus was similar to R.flavefaciens.At 7 days,the P.chrysosporium treatment group was significantly higher than the P.ostreatus and Dual treatment groups(P<0.05),and there was no significant difference between P.ostreatus and Dual treatment groups.As the time extended to the 28th day,there was no significant difference between P.chrysosporium and P.ostreatus,but both were significantly higher than the Dual treatment group(P<0.05).P.ruminicola,the three fungal treatment groups all had an increasing trend with the prolongation of pretreatment time(P<0.01).Experiment 3:Effects of white rot fungus pretreatment on rumen degradation of white tea by-products and intestinal digestibility of rumen undegraded proteinAccording to the test 1 and 2,the effect of pretreatment for 7 days is the best,so in the test 3,the by-products of white tea after 7 days of pretreatment with three kinds of fungi were selected for the nylon bag test.The purpose of this experiment was to explore the differences in the degradation rules of white tea by-products pretreated by white rot fungi in the rumen of dairy cows,and to provide a theoretical basis for a more comprehensive evaluation of the feeding value of white tea by-products treated with white rot fungi.The rapid degradation fraction of DM in the P.chrysosporium treatment group was the highest(P<0.01),echoing its DM degradation rate.The ED of each group formed a very significant difference,from high to low,P.chrysosporium 63.94%>P.ostreatus 59.78>Dual 56.24%>Control 51.65%(P<0.01).The effective degradation rate of CP in the three fungal treatment groups was significantly higher than that of Control(P<0.01),and the order from high to low was Dual>P.ostreatus>P.chrysosporium>Control.In terms of NDF degradation parameters,62.32%of the P.chrysosporium treatment group was significantly higher than that of other treatment groups(P<0.01),and there was no significant difference among Control,P.ostreatus and Dual.In terms of ADF degradation parameters,the effective degradation rate of 39.00 in the P.chrysosporium treatment group was significantly higher than that in other treatment groups(P<0.01).Conclusion:P.chrysosporium pretreatment for 7 days effectively increased the CP content of white tea by-products and decreased the ADL content of white tea by-products.In the subsequent in vitro and semi-in vitro tests,all indicators were compared with the by-products of the fungal treatment group and the untreated white tea.Therefore,it is recommended to use P.chrysosporium for pretreatment of white tea by-products,and the pretreatment time is 7 days. |
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