不同纤维素与淀粉比率等氮纯化日粮瘤胃发酵挥发性脂肪酸产生量

本文采用持续动态瘤胃模拟装置 (RSI)研究了 6种不同纤维素和淀粉比率 (C S) ;0 .14、0 .4 4、0 .94、1.92、4 .75、15 .76等氮纯化日粮养分瘤胃发酵率及挥发性脂肪酸净产生量。结果显示 :随着日粮中C S的升高 ,72小时发酵后 ,纤维素发酵率由 75 .2 1%下降至 5 0 .2 9% ;对纯化日粮而言 ,有机物发酵率 (FOM OM ,% )在C S为 0 .4 4～ 4 .75时可以保持较高 (6 8%～ 72 % ) ;纯化日粮 72小时发酵后 ,净挥发性脂肪酸产生量 (VFA FOM ,mol g)与日粮可发酵纤维素和可发酵淀粉比率 (FC FS)间呈乘幂负相关 (VFA FOM ,mol g =4 .2 7) (FC FS) - 0 .1 41 6 ,r=- 0 .94 2 7) ,并在 3.4 0～ 5 .5 2之间浮动。表明 ,纯化日粮体外发酵养分发酵率及VFA产生量与日粮结构性碳水化合物与非结构性碳水化合物比率密切相关。

Effects of Cellulose to Starch Ratio in Substrate on in itro olatile Fatty Acids Yield with Equal-nitrogen Purified Substrate

An in vitro 72 hours fermentation using dynamic rumen fermentation simulation instrument(RSI)was conducted to study net total volatile fatty acid production of purified substrates with various ratios of cellulose to starch(0.14～15.76).It indicated that pure cellulose fermentability declined exponentially from 75.21% to 50.29% as cellulose to starch ratio(C/S)increased.Higher organic matter fermentabilities (FOM/OM,%)was found when C/S fluctuated between 0.44 and 4.75:FOM/OM,%=66.581.439(C/S)-0.1257(C/S)2;Net total volatile fatty acid production per fermented OM(VFA/FOM,mol/g)declined exponentially as the ratio of fermentable cellulose to fermentable starch (FC/FS)went up:VFA/FOM,mmol/g=4.2718(FC/FS){-0.1416},n=6,r=-0.9427.It was concluded that both OM fermentability and net volatile fatty acid production were closely related to the ratio of dietary structural carbohydrate to non-structural carbohydrate.