| Cottonseed meal feed is rich in protein but contains toxic substance-free gossypol.Tarim wapitideer have certain tolerance to toxic plants.The in vitrodigestion tests of Tarim wapitideer and sheep withdifferent free gossypol contents and in vivodigestion tests of Tarim wapitideer and sheep with the same free gossypol content were conducted.The rumen fermentation parameters,blood biochemical indexes and rumen microbialdiversity of Tarim wapitideer and sheep weredetermined.In order to explore rumen microorganisms of Tarim wapitideer,and provide scientific basis for exploring the tolerance mechanism of Tarim wapitideer to free gossypol.This experiment includes the following two aspects :Experiment 1 : Effects ofdifferent free gossypol addition levels on rumen in vitro fermentation parameters of Tarim wapitideer and sheepIn this study,the rumen fluid of Tarim wapiti and sheep was inoculated withdifferent concentrations of free gossypol for in vitro fermentation.The aim of this study was to compare the tolerance of Tarim wapitideer and sheep to free gossypol.0mg/kg,125mg/kg,250mg/kg,500mg/kg,750mg/kg and 1 000mg/kg free gossypol were added for in vitro fermentation of sheep,and 0mg/kg,250mg/kg,500mg/kg,750mg/kg,1 000mg/kg and 1250mg/kg free gossypol were added for in vitro fermentation of Tarim wapitideer.Gas production,pH,ammonia nitrogen,volatile fatty acids,dry matterdegradation rate and crude proteindegradation rate weredetermined.The results showed that with the increase of free gossypol addition,the gas production,pH,volatile fatty acids,dry matterdegradation rate and crude proteindegradation rate of Tarim wapitideer and sheep at each time point showed adownward trend.When free gossypol concentration was higher than 250mg/kg,the gas production,pH,volatile fatty acids,dry matterdegradation rate and crude proteindegradation rate of sheep at each time point was significantly lower than that of the control group(P<0.05).Ammonia nitrogen showed an upward trend,and the ammonia nitrogen content at each time point of 250mg/kg was significantly higher than that of the control group(P<0.05).The gas production,pH,volatile fatty acids,dry matterdegradation rate and crude proteindegradation rate of Tarim wapitideer at each time point when free gossypol content was greater than 500mg/kg was significantly lower than that in the control group(P<0.05).Ammonia nitrogen showed an upward trend,and the ammonia nitrogen content at each time point of 500mg/kg was significantly higher than that of the control group(P<0.05).In this in vitro fermentation test,the gossypol additions that had an effect on the in vitro fermentation parameters of Tarim wapitideer and sheep were 500mg/kg and 250mg/kg.Experiment 2 : Effects of free gossypol on rumen microbial fermentation and blood biochemical indexes of Tarim wapitideer and sheepIn this study,the effects of feed with the same free gossypol concentration on rumen fermentation,blood biochemical indexes and rumen microbialdiversity of Tarim wapitideer and sheep were compared to analyze the reasons why Tarim wapitideer were more tolerant to free gossypol than sheep.According to Experiment 1,the free gossypol content in thediet of the feeding experiment wasdetermined to be 500mg/kg,and the feeding experiment was conducted on the Tarim wapitideer and sheep.The pre-feeding period was 20d,and the normal feeding period was 30d.ruminal fluid and blood were collected at 2h after morning feeding on the before feeding period,the 15 thday of normal feeding period and the 30 thday of normal feeding period.The results showed that there were no significantdifferences in pHvalue,the volatile fatty acids in rumen fluid of Tarim wapitideer fed with 500mg/kg free gossypol atbefore feeding period,15d of normal feeding period and 30d of normal feeding period(P>0.05).The contents of ammonia nitrogen,microbial crude protein and free gossypol in rumen fluid showed an upward trend and thedifferences were significant indifferent periods(P<0.05).There was no significantdifference in the total antioxidant capacity,Glutamic-oxaloacetic transaminase,Aspartate aminotransferase,Alanine aminotransferase and free gossypol content in the blood of the Tarim wapitideer(P>0.05).The contents of reduced glutathione and catalase in 500mg/kg free gossypol treatment group were significantly higher than those in control group(P<0.05).The MDA content in each period showed adownward trend,and thedifference was significant(P<0.05).The contents of Aspartate aminotransferase and Alanine aminotransferase in rumen fluid of sheep atdifferent stages increased significantly(P<0.05),while the contents of neutral protease and endo-β-1,4-glucanase in 500mg/kg free gossypol treatment group were significantly higher than those in sheep(P<0.05).There was no significantdifference in the number of protozoa between the 500mg/kg free gossypol treatment group and the 500mg/kg free gossypol treatment group at 15d and 30d(P>0.05),but they were significantly higher than the control group(P<0.05);only the Simpson index of bacteria in the Tarim wapitideer group was significantly lower than that in the 500mg/kg free gossypol treatment group for 30days(P<0.05).The relative abundance of Bacteroidetes in Tarim wapitideer fed with 500mg/kg free gossypol for 30days was significantly lower than that in sheep(P<0.05),while the relative abundance of Firmicutes,Patescibacteria,Tenericutes,Mortierellomycota,Chloromycota,Glomeromycota,Rikenellacea e＿RC9＿gut＿group and Aspergillus in Tarim wapitideer were significantly higher than those in sheep(P<0.05).Through thedetermination of glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase 500mg/kg free gossypol feeding 30daysdid not causedamage to the body of Tarim reddeer,causeddamage to the sheep body.The neutral protease and endo-β-1,4-glucanase in rumen fluid had significant effects on gossypol,and gossypol had significant effects on the scientific research bacteria and Aspergillus in rumen.In summary,through in vitro fermentation,it was found that with the increase of free gossypol content,gas production,pH value,dry matterdegradation rate,proteindegradation rate and volatile fatty acid content all showed adownward trend,and ammonia nitrogen showed an upward trend.The content of free gossypol that had an effect on the in vitro fermentation parameters of Taliban and sheep was 500mg/kg and 250mg/kg,respectively.Feeding test found that 500mg/kg free gossypol feeding sheep and Tarim reddeer 30d causeddamage to sheep body,did not causedamage to Tarim reddeer body.The increase in the activities of fiber enzymes and proteases and the relative abundance of Aspergillus indicated that the tolerance of Tarimdeer to free gossypol increased the activities of fiber enzymes and proteases and the relative abundance of Aspergillus. |
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