不同化学处理对小麦秸秆营养成分和体外发酵参数的影响OA

This experiment aimed to study the effects of single or combined treatments of urea,sodium hydroxide,and sodium bicarbonate on the nutrients and in vitro fermentation parameters of wheat straw.The addition amounts of urea and sodium hydroxide were both 0 and 3%of the dry matter(DM)of the straw,and the addition amount of sodium bicarbonate was 0 and 2%of the straw DM.Samples were collected after being sealed and treated at room temperature for 30 d to analyze the nutrients of the wheat straw.Using the rumen fluid from three healthy Simmental cross-bred beef cattle with permanent rumen fistulas as the donors,the in vitro dry matter digestibility,gas production,and fermentation parameters of the treated wheat straw after 48 h were determined by the in vitro gas production method.The results showed that:① individual,two-factor,and three-factor treatments with urea,NaOH,and NaHCO₃ all significantly affected the crude protein(CP)content in wheat straw(P<0.05).Urea,NaOH,and NaHCO₃ treatments significantly affected the neutral detergent fiber(NDF)content(P<0.05).NaOH treatment remarkably reduced the acid detergent fiber(ADF)and acid detergent lignin(ADL)contents(P<0.05),while NaHCO₃ treatment significantly affected the ADF content(P<0.05).However,there were no significant interactive effects among the treatment factors(P>0.05).② Both urea and NaOH treatments significantly affected the in vitro dry matter degradation rate(P<0.05).Addition-ally,urea and NaOH treatments notably enhanced the cumulative gas production during the in vitro fermenta-tion of wheat straw(P<0.05).Moreover,significant two-way and three-way interactive effects were observed among urea,NaOH,and NaHCO₃(P<0.05).③ Urea treatment significantly affected the concentrations of ammonia nitrogen(NH₃-N),acetic acid,propionic acid,and butyric acid(P<0.05).In contrast,NaOH and NaHCO₃ treatments had no significant impacts on the concentrations of NH₃-N,acetic acid,propionic acid,or butyric acid during the in vitro fermentation of wheat straw,and there were no significant interactive effects among the treatment factors(P>0.05).In conclusion,the 3%urea+3%NaOH+2%NaHCO3 combined treat-ment can significantly improve the nutritional value and in vitro fermentation characteristics of wheat straw.