Effects Of Combined Use Of Sulfate And Nitrate On Rumen Fermentation,Nutrient Degradation And Gas Production In Liaoning Cashmere Goats

In this experiment,six healthy adult Liaoning velvet goats were used as rumen fluid donors to conduct in vitro rumen fluid fermentation tests to investigate the effects of combined sulfate and nitrate on rumen fermentation,fiber degradation and methane（CH₄）production in Liaoning velvet goats,and to focus on the changes of hydrogen sulfide（H₂S）levels in the rumen to provide a theoretical basis for subsequent studies related to CH₄emission in ruminants.The experiment was conducted in a 2×2 factorial design,with sodium sulfate（Na₂SO₄）added at 0.335%and 0.67%of the air-dry basis of the diet and potassium nitrate（KNO₃）added at 0.43%and 0.97%of the air-dry basis of the diet.Because the addition of KNO₃ will increase the nitrogen level of the diet,urea was added in the low KNO₃ addition group to balance the nitrogen level of the diet,so as to eliminate the influence of nitrogen level on this experiment.The test results showed that the addition of 0.97%KNO₃ to the diet increased the degradation rate of dry matter（DM）,neutral detergent fiber（NDF）,acid detergent fiber（ADF）,and the concentration of mycoprotein（MCP）,acetic acid,propionic acid,and butyric acid（P<0.01）at the beginning of fermentation for 4 h.However,the effect on these indicators was not significant at the end of fermentation for 48 h（P>0.05）.The addition of 0.335%Na₂SO₄ to the diet significantly increased the concentrations of acetic acid,propionic acid and butyric acid in the rumen throughout the in vitro fermentation process（P<0.01）,while the interaction of Na₂SO₄ and KNO₃ also had a significant effects on the concentrations of acetic acid,propionic acid and butyric acid in the rumen（P<0.01）.When 0.97%KNO₃ was added to the diet along with 0.335%Na₂SO₄,the highest concentrations of acetic acid,propionic acid and butyric acid were maintained in the rumen throughout the fermentation stage,with acetic acid and butyric acid concentrations being significantly higher（P<0.01）than the other three groups at 4h,24h and 48h,and propionic acid concentrations being significantly higher（P<0.01）than the other three groups at 4h and 8h.In contrast,the concentrations of CH₄ and H₂S in this group remained the lowest throughout the fermentation process,and the concentrations of CH₄ at 4h,8h and 24h were significantly lower than those in the other three groups（P<0.01）,and the concentrations of H₂S at 4h were significantly lower than those in the other three groups（P<0.01）.CH₄ concentration in the rumen was negatively correlated with acetic acid concentration and positively correlated with H₂S.In conclusion,the addition of KNO₃ at 0.97%and Na₂SO₄ at 0.335%was more favorable to the fermentation of feeds in the rumen of Liaoning goats,and it could effectively reduce the CH₄production and ensure that the H₂S concentration in the rumen would not be too high.