不同品种玉米秸秆体外发酵及养分瘤胃原位降解特性研究

In vitro fermentation and rumen in vivo nutrient degradation characteristics of maize stalks from different varieties

【目的】探究5个玉米品种完熟期秸秆体外发酵及营养成分瘤胃原位降解特性,为其在草食畜中的利用提供营养技术参数。【方法】选用普通玉米(科湘玉11号,CM)、高油玉米(高油115,HOM)、糯玉米(科湘糯玉1号,WM)、饲用玉米(沪青1号,FM)和甜玉米(科湘甜玉1号,SM)等5个玉米品种为试验材料,于抽穗后第50天(完熟期)采集秸秆样品,利用体外产气试验及瘤胃原位降解试验测定其体外发酵特性及干物质(DM)、粗蛋白(CP)和中性洗涤纤维(NDF)降解率,研究其瘤胃降解动力学参数变化规律。【结果】饲用玉米的产气速度(k)显著高于糯玉米和普通玉米(P<0.05);初始发酵速率(FRD 0)显著高于糯玉米(P<0.05),极显著高于普通玉米(P<0.01)。甜玉米的体外干物质消化率(DMD)显著高于糯玉米、普通玉米和高油玉米(P<0.05)。普通玉米秸秆发酵液中氨态氮浓度极显著高于其他4种玉米(P<0.01)。高油玉米秸秆体外发酵液中总挥发性脂肪酸(TVFA)浓度极显著高于除普通玉米外的其他3种玉米(P<0.01),而普通玉米则显著高于糯玉米和甜玉米(P<0.05)。甜玉米秸秆发酵液乙酸及高油玉米秸秆异丁酸物质的量比例显著高于饲用玉米;饲用玉米秸秆丁酸物质的量比例极显著高于其他4种秸秆。饲用玉米、高油玉米秸秆的干物质有效降解率均显著高于甜玉米(P<0.05);饲用玉米秸秆粗蛋白的有效降解率显著高于其他3个品种(P<0.001),普通玉米秸秆粗蛋白的有效降解率极显著高于糯玉米和高油玉米;饲用玉米和高油玉米秸秆中性洗涤纤维有效降解率分别显著和极显著高于甜玉米。【结论】不同玉米品种秸秆体外发酵及体内降解特性存在差异,饲用玉米和高油玉米等新型玉米品种秸秆具有与普通玉米相近甚至更高的营养消化率。

【Objective】The in vitro fermentation characteristics and rumen in situ degradation characteristics of nutrient components of five maize varieties at the full mature stage were explored to provide nutritional technical parameters for their utilization by herbivorous animals.【Method】Five maize varieties including conventional maize(Kexiangyu No.11,CM),high-oil maize(Gaoyou 115,HOM),waxy maize(Kexiang Nuoyu No.1,WM),feed maize(Huqing No.1,FM)and sweet maize(Kexiang Tianyu No.1,SM)were used in this experiment.The maize stalks were sampled on the 50th day after heading(full maturity),and all samples were analyzed for in vitro fermentation characteristics and in vivo degradability of dry matter(DM),crude protein(CP)and neutral detergent fiber(NDF)using in vitro gas production technology and rumen nylon bag technology.【Result】The gas production rate(k)of FM was significantly higher than that of WM and CM(P<0.05),and the initial fermentation rate(FRD 0)of FM was significantly higher than that of WM(P<0.05)and extremely significantly higher than that of CM(P<0.01).The in vitro dry matter digestibility(DMD)of SM was significantly higher than that of WM,CM and HOM(P<0.05).The concentration of ammonia nitrogen in the fermentation fluid of CM was significantly higher than that of other varieties(P<0.01).The total volatile fatty acid(TVFA)content in the in vitro fermentation fluid of HOM stalk was significantly higher than that of other varieties except CM(P<0.01),while CM was significantly higher than that of WM and SM(P<0.05).The proportion of acetic acid in the fermentation fluid of SM and the proportion of isobutyric acid in HOM were significantly higher than those of FM.The proportion of butyric acid in FM was significantly higher than that of other varieties.The effective degradability of DM(ED DM)of FM and HOM was significantly higher than that of SM(P<0.05).The effective degradability of crude protein(ED CP)of FM was extremely significantly higher(P<0.01)than other varieties except CM,and CM was significantly higher(P<0.01)than that of WM and HOM in ED CP.The effective degradability of NDF(ED NDF)of FM and HOM was significantly(P<0.05)and extremely significantly(P<0.01)higher than that of SM,respectively.【Conclusion】There were differences in in vitro fermentation and in vivo degradation characteristics of stalks among different maize varieties,and new maize varieties had similar or even higher nutrient digestibility than common maize varieties.