RDP相同NFC及硫水平不同的日粮对人工奶牛瘤胃发酵影响

The effect of non-fiber carbohydrate and sulfur in diets with same level of ruminally degradable protein on in vitro fermentation

文章研究的目的是瘤胃降解蛋白(RDP)相同,非结构性碳水化合物(NFC)及硫水平不同的日粮对人工奶牛瘤胃发酵的影响。试验选择3头健康的荷斯坦奶牛提供瘤胃液,试验采用双因素试验设计[3×4:NFC与RDP比值分别为3.35、4和4.8,硫(S)的水平分别为0.15%、0.20%、0.25%和0.30%],试验结果表明,不同NFC/RDP水平的日粮体外发酵,pH值(2 h除外)、产气量、丙酸、丁酸、菌体蛋白(MCP)差异显著(P<0.05);NH_3-N浓度在8、12 h和24 h差异显著(P<0.05);乙酸在2、4、8 h和12 h差异显著(P<0.05);干物质降解率(DMD)在2、4、8 h和24 h差异显著(P<0.05)。硫对pH值和NH_3-N浓度在12 h和24 h的影响显著(P<0.05),而且产气量、丙酸、丁酸和菌体蛋白含量也有明显的影响(P<0.05);但对乙酸浓度的影响不显著。总的来说,当NFC/RDP值为4时,瘤胃pH值、产气量、乙酸、微生物粗蛋白含量和干物质降解率(DMD)增加,但NH_3-N、丙酸和丁酸浓度降低,适当的补充硫(硫含量为0.25%),瘤胃pH值、产气量、丙酸、丁酸、MCP含量会增加,然而NH_3-N浓度降低,同时两者之间存在这交互作用。综合各项指标表明日粮NFC/RDP值为4、硫水平为0.25%的日粮可明显改善瘤胃内环境、促进瘤胃发酵提高饲料各成分的降解率。

The objective of this thesis was to investigate the effects of non-fiber carbohydrate （NFC） and sulfur （S） in diets with same level of ruminally degradable protein （RDP） on in vitro rumen fermentation. Three Holstein cows were chosen to provide rumen fluid tbr in vitro tureen fermentation. An experimental design with two factors （3×4： 3.35, 4 and 4.8 ratios of NFC to RDP, 0.15%, 0.20%, 0.25% and 0.30% S levels） were used. The results showed that the different NFC/RDP value influence on pH （except for 2 h）, gas production, propionate, butyrate, Microbial crude protein （MCP） were significant （P〈0.05）. NH3-N concentration was changed in 8 h, 12 h and 24 h（P〈0.05）; acetate was changed in 2 h, 4 h, 8 h and 12 h （P〈0.05）; dry matter degradation （DMD） were changed in 2 h, 4 h, 8 h and 24 h（P〈 0.05）. Of sulfur, influence on pH and NH3-N concentration（at 12 h and 24 h） were significant （P〈 0.05） and moreover significant effect on gas production, propionate, butyrate and microbial crude protein yield were observed（P〈0.05）; but there was nearly no significant change for tration. On the whole, when the RDP value was 4, values of pH, acetate, microbial crude protein acetate concenratio of NFC to gas production, yield were increased（P〈0.05）, but NH3-N, propionate and butyrate concentration were decreased; the proper sulfur supplement（level of 0.25%） increased pH, gas production, propionate, butyrate,bacteria protein, and however reduced NH3-N eoneentration; meanwhile interaction between the ratio and S existed. All in all, the treatment with NFC/RDP value was 4 and Ihe level of sulfur was 0.25% can improve rumen environment,promote the degradation of diet nutrition significantly.