不同粗饲料组合对晋南牛瘤胃体外发酵特性的研究

Effects of different roughage combinations on in vitro rumen fermentation characteristics of Jinnan cattle

旨在研究全株玉米青贮(WCS)、小麦秸秆(WS)和苜蓿青贮(AS)不同组合比例对晋南牛瘤胃体外发酵特性的影响,筛选不同饲料组合应用的最适比例。将全株玉米青贮、小麦秸秆、苜蓿青贮以不同比例组合(80∶10∶10,70∶10∶20,70∶20∶10,60∶10∶30,60∶20∶10,60∶30∶10,50∶10∶40,50∶20∶30,50∶30∶20,50∶40∶10,0∶100∶0,100∶0∶0,0∶0∶100)进行体外发酵试验,测定分析不同饲料组合对体外产气量(GP)、干物质降解率(IVDMD)、pH、氨态氮(NH3-N)、挥发性脂肪酸(VFA)的影响,计算各组合的单项组合效应值(SFAEI)和综合组合效应值(MFAEI)。结果表明,全株玉米青贮、小麦秸秆和苜蓿青贮的组合比例对GP的影响极显著(P<0.01)。随着全株玉米青贮比例增加,GP逐渐增加。各组体外发酵液pH保持为6.68~6.89(P<0.01)。NH3-N的变化范围为14.31~26.01 mg·100 mL^(-1)(P<0.01)。全株玉米青贮比例一定时,IVDMD随着苜蓿青贮比例增加而增加。不同比例组合的全株玉米青贮、小麦秸秆和苜蓿青贮体外发酵液中VFA浓度差异极显著(P<0.01)。60∶30∶10组乙酸和总挥发性脂肪酸(TVFA)浓度显著高于其他各组(P<0.05),其丙酸浓度也为最高(13.99 mmol·L^(-1))。各比例组合乙酸/丙酸在2.76~3.20,组间差异不显著(P>0.05)。不同组合的综合组合效应值均为正组合效应,70∶20∶10综合组合效应值(0.9343)最高。由此可见,全株玉米青贮、小麦秸秆和苜蓿青贮比例为70∶20∶10时,组合效应最佳。

The objective of this experiment was to study the effects of different roughage combinations of whole plant corn silage,wheat straw,and alfalfa silage on rumen in vitro fermentation characteristics of Jinnan cattle.Whole plant corn silage,wheat straw,and alfalfa silage were fermented in different ratios(80∶10∶10,70∶10∶20,70∶20∶10,60∶10∶30,60∶20∶10,60∶30∶10,50∶10∶40,50∶20∶30,50∶30∶20,50∶40∶10,0∶100∶0,100∶0∶0,0∶0∶100,respectively).Gas production(GP),in vitro dry matter degradation rate(IVDMD),pH,ammonia nitrogen(NH3-N),and volatile fatty acid(VFA)were measured,and the single factor associative effects index(SFAEI)and multiple factors associative effects index(MFAEI)of the different feedstuff ratios were calculated.It was found that GP differences among the different roughage combinations were extremely significant(P<0.01).The GP gradually increased with increase in the proportion of whole plant corn silage;the pH of each group was maintained at 6.68-6.89(P<0.01)and NH3-N was 14.31-26.01 mg·100 mL^(-1)(P<0.01).With the proportion of whole plant corn silage constant,IVDMD increased as the proportion of alfalfa silage was increased.Differences in rumen VFA levels among the different feedstuff ratios were also extremely significant(P<0.01).The concentration of acetic acid and total volatile fatty acid(TVFA)in the 60∶30∶10 formulation was significantly higher than in other formulations(P<0.05),and the concentration of propionic acid was also the highest(13.99 mmol·L^(-1))in this formulation.The ratio of acetic acid to propionic acid ranged from 2.76-3.20,and there was no significant difference between the formulations(P>0.05).The MFAEI of the various feed formulations was positive,and the MFAEI of the 70∶20∶10 formulation was the highest(0.9343).In conclusion,in this study,the largest associative effects occurred when the proportion of whole plant corn silage,wheat straw and alfalfa silage was,respectively,70∶20∶10.