Departamento de Produção Agrícola e Animal (DPAA), Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, P-1349-017 Lisboa Codex, Portugal.
J Sci Food Agric. 2010 Apr 30;90(6):949-55. doi: 10.1002/jsfa.3891.
Dry matter degradability (DMD) parameters (a, b and c in the Ørskov and McDonald model) are usually determined by the nylon bag technique. The aim of this study was to estimate DMD parameters of ruminant mixed diets, which are in general unavailable, through multiple linear regressions on their chemical composition (ash, crude protein, neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL)). The regressions were based on data from 77 feeds.
The prediction model for a was reduced to a simple linear regression on NDF (adjusted R(2) = 0.727, F test P < 0.001). A regression model for b was obtained with ADL as the sole predictor (adjusted R(2) = 0.691, P < 0.001). The model's upper asymptote (a + b) was predicted from ADL, NDF and ash (adjusted R(2) = 0.908, P < 0.001). Modelling c proved more difficult (adjusted R(2) with all five predictors = 0.481, P < 0.001).
Regressing model parameters on feed chemical composition is a promising method for estimating the degradability of mixed diets, providing an alternative to invasive and expensive laboratory techniques.
干物质降解率（DMD）参数（Ørskov 和 McDonald 模型中的 a、b 和 c）通常通过尼龙袋技术来确定。本研究的目的是通过对其化学成分（灰分、粗蛋白、中性洗涤剂纤维（NDF）、酸性洗涤剂纤维（ADF）和酸性洗涤剂木质素（ADL））进行多元线性回归，来估计反刍动物混合日粮的 DMD 参数，这些参数通常无法获得。该回归基于 77 种饲料的数据。
a 的预测模型简化为 NDF 的简单线性回归（调整 R²=0.727，F 检验 P<0.001）。仅用 ADL 获得了 b 的回归模型（调整 R²=0.691，P<0.001）。模型的上限（a+b）由 ADL、NDF 和灰分预测（调整 R²=0.908，P<0.001）。c 的建模更为困难（用所有五个预测因子的调整 R²=0.481，P<0.001）。
将模型参数回归到饲料化学成分是一种估计混合日粮降解率的有前途的方法，为侵入性和昂贵的实验室技术提供了替代方法。
