Powell Christopher D, Dhanoa Mewa S, Garber Anna, Murray Jo-Anne M D, López Secundino, Ellis Jennifer L, France James
Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada.
Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth SY23 3EB, UK.
Animals (Basel). 2020 Feb 17;10(2):308. doi: 10.3390/ani10020308.
Two models are proposed to describe atypical biphasic gas production profiles obtained from in vitro digestibility studies. The models are extensions of the standard Mitscherlich equation, comprising either two Mitscherlich terms or one Mitscherlich and one linear term. Two models that describe typical monophasic gas production curves, the standard Mitscherlich and the France model [a generalised Mitscherlich (root-) equation], were assessed for comparison. Models were fitted to 25 gas production profiles resulting from incubating feedstuffs with faecal from equines. Seventeen profiles displayed atypical biphasic patterns while the other eight displayed typical monophasic patterns. Models were evaluated using statistical measures of goodness-of-fit and by analysis of residuals. Good agreement was found between observed atypical profiles values and fitted values obtained with the two biphasic models, and both can revert to a simple Mitscherlich allowing them to describe typical monophasic profiles. The models contain kinetic fermentation parameters that can be used in conjunction with substrate degradability information and digesta passage rate to calculate extent of substrate degradation in the rumen or hindgut. Thus, models link the in vitro gas production technique to nutrient supply in the animal by providing information relating to digestion and nutritive value of feedstuffs.
提出了两种模型来描述体外消化率研究中获得的非典型双相产气曲线。这些模型是标准米氏方程的扩展，由两个米氏项或一个米氏项和一个线性项组成。评估了两种描述典型单相产气曲线的模型，即标准米氏模型和法国模型[广义米氏（根）方程]，以作比较。将模型拟合到25条产气曲线，这些曲线是通过将饲料与马粪便一起孵育得到的。17条曲线呈现非典型双相模式，而其他8条呈现典型单相模式。使用拟合优度的统计量度并通过残差分析对模型进行评估。观察到的非典型曲线值与用两种双相模型获得的拟合值之间存在良好的一致性，并且两者都可以还原为简单的米氏模型，从而能够描述典型的单相曲线。这些模型包含动力学发酵参数，可与底物降解性信息和消化物通过率结合使用，以计算瘤胃或后肠中底物的降解程度。因此，这些模型通过提供与饲料消化率和营养价值相关的信息，将体外产气技术与动物的营养供应联系起来。
