木薯渣与甜菜颗粒粕组合效应对奶牛瘤胃发酵特性的影响

本试验旨在通过体外产气法研究木薯渣与甜菜颗粒粕组合用作泌乳中后期奶牛饲料的可行性及适宜组合比例。试验设计7个处理:木薯渣分别以0%(对照组)、5%、10%、15%、20%、25%和30%与甜菜颗粒粕(风干物质基础)组合,使用AGRS-Ⅲ型微生物发酵产气系统进行体外瘤胃微生物发酵试验,监测体外培养3、6、12、24、48h后的发酵液pH、氨态氮(NH3-N)、微生物蛋白(MCP)含量和体外培养48h后干物质消失率(IVDMD)、累积产气量(GP)及挥发性脂肪酸(VFA)含量等指标。结果表明:体外培养48 h后,GP和底物的最大降解率(RmaxS)随木薯渣占比增加呈线性或二次增加(P<0.05);发酵液各VFA和TVFA含量均随木薯渣占比增加呈线性或二次降低(P<0.05);根据多项组合效应值,以0%组为对照时,5%组和10%组表现为正组合效应,其余组合均表现为负组合效应。在本试验条件下,当木薯渣与甜菜颗粒粕组合使用,且木薯渣为5%~10%较为适宜,但此结果仍需奶牛饲养试验进一步验证。

Effects of Different Proportions of Cassava Residue and Pelleted Beet Pulp on Rumen Fermentation Characteristics of Dairy Cows

The purpose of this experiment was to evaluate the feasibility and suitable ratio of the combination of cassava residue and pelleted beet pulp in dairy cow diets in the mid to late lactation period by in vitro gas test. A total of seven treatments in the experiment: cassava residue were combined with pelleted beet pulp(air-dry matter basis) at a ratio of 0%(control), 5%, 10%, 15%, 20%, 25% and 30%, using AGRS-Ⅲ-Type microbial fermentation gas production system for in vitro rumen microbial fermentation test, monitoring the pH, ammonia nitrogen(NH3-N), microbial protein(MCP) content of the fermentation broth when in vitro cultured for 3, 6, 12, 24, 48 h, dry matter disappearance rate(IVDMD), cumulative gas production(GP) and volatile fatty acid(VFA) were recorded after in vitro cultured for 48 h. The results showed that after 48 h of in vitro cultivation: the maximum degradation rate of GP and substrate(RmaxS) increased linearly or quadratically with the increase of the proportion of cassava residue(P<0.05);the content of each VFA and total VFA in the fermentation broth showed a linear or quadratic decrease(P<0.05) with the ratio of cassava residue increasing. Besides, the multiple combination effect values of 5% and 10% treatment compared with control showed a positive combination effect, and the remaining combinations all showed a negative combination effect. In summary, under this test condition, when cassava residue and pelleted beet pulp are used in combination, and it is suitable when the ratio of cassava residue is less than or equal to 10%.This result still needs further verification using dairy cows.