Nadeau E M, Buxton D R, Lindgren E, Lingvall P
Iowa State University, Ames 50011, USA.
J Dairy Sci. 1996 Dec;79(12):2207-16. doi: 10.3168/jds.S0022-0302(96)76597-9.
The objectives of this study were to determine the effects of cellulase (from Trichoderma longibrachiatum) combined with formic acid, applied before ensiling, on the subsequent concentration and composition of the cell wall and on the extent and rate of in situ cell-wall digestion of orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.). Treated and control forages of both plant species were ensiled for at least 60 d before being ruminally digested by two fistulated cows. Analyses of NDF, ADF, and acid detergent lignin were conducted sequentially on original and digested samples. Data were fitted with a first-order, nonlinear model to estimate extents and rates of digestion of potentially digestible NDF, cellulose, and hemicellulose. The concentration of indigestible residue and the discrete lag time before digestion were also determined for the cell-wall components. After ensiling, the mean NDF concentration of treated silages was 19% lower than that of control silages; the effect was greater for orchardgrass than for alfalfa. The extent of digestion of NDF, cellulose, and hemicellulose, respectively, was 33, 37, and 27% lower for treated silages than for control silages. Treatment effects on the extent of digestion varied between plant species. Cellulose from treated orchardgrass was digested 19% more slowly than cellulose from the control silage. Indigestible residue concentrations of NDF, cellulose, and hemicellulose, respectively, were 7, 8, and 7% lower in treated silages than in control silages. Thus, extensive cell-wall degradation by cellulase during ensiling resulted in less digestible cell-wall material for ruminal digestion but greater total cell-wall degradation, including that during ensiling and ruminal incubation, especially during early digestion in the rumen.
本研究的目的是确定在青贮前施用的纤维素酶（来自长枝木霉）与甲酸相结合，对随后细胞壁的浓度和组成以及果园草（鸭茅）和苜蓿（紫花苜蓿）原位细胞壁消化的程度和速率的影响。两种植物的处理和对照草料在被两头装有瘤胃瘘管的奶牛进行瘤胃消化之前，至少青贮60天。对原始样品和消化后的样品依次进行中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）和酸性洗涤木质素的分析。数据采用一阶非线性模型进行拟合，以估计潜在可消化NDF、纤维素和半纤维素的消化程度和速率。还测定了细胞壁成分的不可消化残渣浓度和消化前的离散滞后时间。青贮后，处理过的青贮料的平均NDF浓度比对照青贮料低19%；果园草的这种效果比苜蓿更明显。处理过的青贮料中NDF、纤维素和半纤维素的消化程度分别比对照青贮料低33%、37%和27%。处理对消化程度的影响因植物种类而异。处理过的果园草中的纤维素比对照青贮料中的纤维素消化速度慢19%。处理过的青贮料中NDF、纤维素和半纤维素的不可消化残渣浓度分别比对照青贮料低7%、8%和7%。因此，青贮期间纤维素酶对细胞壁的广泛降解导致瘤胃消化中可消化的细胞壁物质减少，但包括青贮期间和瘤胃培养期间，尤其是瘤胃早期消化期间在内的总细胞壁降解量更大。
