饲料油菜不同添加比例对滩羊瘤胃体外发酵的影响

Effects of mixed silage containing corn straw and rape on the in vitro fermentation characteristics of rumen fluid from Tan sheep

本试验旨在研究不同比例的饲料油菜(Brassica napus)和玉米(Zea mays)秸秆混贮对滩羊体外发酵参数及营养物质降解率的影响。以水分含量较高的饲料油菜作为混贮水分调节因子,调制试验组混贮的水分含量为50%、55%、60%、65%和70%,同时调制玉米秸秆黄贮作为对照组。密封发酵60 d后取样,作为滩羊瘤胃体外发酵底物,每组3个重复,进行体外发酵试验,测定体外发酵的各项指标。结果表明:1)干物质降解率(dry matter digestibility,DMD)随着饲料油菜添加比例的增加而显著上升(P<0.05),其中对照组DMD最低,为48.01%,70%水分组DMD最高,为66.81%;中性洗涤纤维降解率(neutral detergent fiber digestibility,NDFD)在各组间无显著差异(P>0.05)。2)试验组滩羊体外发酵的产气量均显著高于对照组(P<0.05),但5个试验组之间无显著差异(P>0.05)。3)各组滩羊体外发酵液中pH值、氨态氮(NH3-N)浓度、总挥发性脂肪酸(total volatile fatty acids,TVFA)浓度、乙酸、丙酸、丁酸、异丁酸和异戊酸比例均无显著差异(P>0.05)。综上,70%水分组饲料油菜混贮的体外发酵效果较好,即饲料油菜与玉米秸秆混贮比例为79.45∶20.55。然而,在实际滩羊养殖中,饲料油菜混贮的比例还需进一步通过饲养试验确定。

The objective of this study was to evaluate the effects of dietary supplementation with rape on the in vitro fermentation of rumen fluid from Tan sheep.Rape,which has a high water content,was mixed with yellow corn straw in various ratios to produce silage containing 50%,55%,60%,65%,and 70%moisture;unmixed yellow corn straw was used as the control group.Samples underwent 60 days of in vitro fermentation in sealed containers containing rumen fluid from Tan sheep,with three repeats in each group,after which they were analyzed.The results showed that the dry matter digestibility(DMD)increased with the proportion of rape(P<0.05);the lowest DMD was 48.01%in the control group,and the highest DMD was 66.81%in the 70%moisture group.There was no significant difference in neutral detergent fiber digestibility between groups(P>0.05).Gas production was significantly higher in the experimental groups than in the control group(P<0.05),but there was no significant difference among the five experimental groups(P>0.05).There were no significant differences between groups in terms of pH value,ammonia–nitrogen(NH3-N)concentration,total volatile fatty acid concentration,or levels of acetic,propionic,butyric,isobutyric,or isovaleric acids(P>0.05).In conclusion,the silage mix with 70%moisture content(79.45∶20.55 ratio of rape to corn straw)had the best effects on in vitro fermentation.However,the ideal proportion of rape to be included in mixed silage for Tan sheep needs to be determined using feeding experiments.