燕麦与苜蓿不同比例组合对驴盲肠体外发酵的影响

研究燕麦干草与苜蓿不同比例组合对驴盲肠液体外发酵的影响,旨在为肉驴养殖中粗饲料的科学利用提供理论依据。将燕麦干草和苜蓿按干物质比为80∶20、60∶40、40∶60和20∶80分为Ⅰ、Ⅱ、Ⅲ、Ⅳ组,通过体外产气法与人工瘤胃持续发酵法培养2、4、8、12和24 h,各时间点3个重复,发酵终止后测定发酵参数和饲草养分降解率,通过24 h时发酵参数的加权估算值计算饲草组合效应值。结果表明:1)燕麦与苜蓿不同比例组合影响了其养分降解率,随着苜蓿比例的增加,干物质(DM)和酸性洗涤纤维(ADF)降解率增大,Ⅳ组显著高于Ⅰ组(P<0.05),各组中性洗涤纤维(NDF)降解率差异不显著(P>0.05)。2)随着苜蓿含量的增加,pH逐渐升高,Ⅳ组显著高于Ⅰ组(P<0.05);各时间点产气量(GP)均为Ⅱ组显著高于其余3组(P<0.05),且24 h时Ⅳ组显著高于Ⅰ和Ⅲ组(P<0.05);从发酵12 h开始Ⅲ、Ⅳ组氨态氮(NH_3-N)浓度显著高于Ⅰ、Ⅱ组(P<0.05);24 h时Ⅱ组微生物蛋白(MCP)浓度显著高于Ⅲ组(P<0.05),与Ⅰ、Ⅳ组无显著差异(P>0.05);燕麦与苜蓿不同比例组合对挥发性脂肪酸(VFA)有显著影响,24 h时Ⅰ和Ⅳ组丙酸浓度显著高于Ⅱ和Ⅲ组(P<0.05),而Ⅰ、Ⅱ组总VFA(TVFA)含量显著高于Ⅲ、Ⅳ组(P<0.05)。3)发酵24 h后Ⅰ、Ⅱ和Ⅳ组均产生正组合效应,且Ⅳ组效应值最大,而Ⅲ组产生负组合效应。综上所述:燕麦与苜蓿按20∶80组合时能提高DM、NDF和ADF降解率,且多项组合效应值更高;燕麦与苜蓿饲喂驴以20∶80组合效果较好。

Effect of different proportions of oat hay and alfalfa on in vitro fermentation in simulated donkey ceca

This study investigated the effects of mixing oat hay and alfalfa in different proportions, on in vitro fermentation rate when incubated with donkey cecum fluid, so as to provide a theoretical basis to determine the optimal use of roughage in donkey breeding. Oat hay and alfalfa were mixed in ratios of 80:20, 60:40, 40:60, 20:80, denoted as treatment groups Ⅰ, Ⅱ, Ⅲ, and Ⅳ respectively. Each mixture was cultured for 2, 4, 8, 12 and 24 hours using continuous fermentation in an artificial rumen, and in vitro gas production measured. There were 3 replicates at each time point. After termination of fermentation, fermentation parameters and nutrient degradation rate of forage were determined. The results showed: 1) With increased alfalfa proportion in the ration, the dry matter (DM) and acid detergent fiber (ADF) degradation rates increased gradually, and were significantly higher for group Ⅳ than for group Ⅰ (P<0.05); there was no significant difference in the degradation of neutral detergent fiber (NDF) (P>0.05). 2) With increase in alfalfa content, the pH increased gradually, and group Ⅳ was significantly higher than group Ⅰ (P<0.05); The gas production (GP) of group Ⅱ was significantly higher than that of the other three groups at each time point (P<0.05). 3) The concentration of NH₃-N in groups Ⅲ and Ⅳ was significantly higher than for groups Ⅰ and Ⅱ from 12 hours (P<0.05). At 24 h, the concentration of microbial protein in group Ⅱ was significantly higher than in group Ⅲ (P<0.05), and there was no significant difference between groups Ⅰ, Ⅱ and Ⅲ (P>0.05). 4) The combination of oat hay and alfalfa had significant effects on volatile fatty acids (VFA), the concentration of propionic acid in groups Ⅰ and Ⅳ was significantly higher than that in groups Ⅱ and Ⅲ at 24 h (P<0.05), while the total VFA content in groups Ⅰ and Ⅱ was significantly higher than that in group Ⅲ and Ⅳ (P<0.05). 5) After 24 h of fermentation, a positive interaction effect was observed in groups Ⅰ, Ⅱ and Ⅳ, with the interaction being largest in group Ⅳ. Conversely, a negative interaction effect was observed in group Ⅲ. We concluded that the optimal proportion of oat hay and alfalfa was 20:80 (group Ⅳ), as the degradation rate of DM, NDF and ADF was improved, and a higher interaction effect occurred.