Institute of Animal Science, University of Bonn, Endenicher Allee 15, 53115 Bonn, Germany.
Institute of Animal Science, University of Bonn, Endenicher Allee 15, 53115 Bonn, Germany.
Comp Biochem Physiol A Mol Integr Physiol. 2021 Jul;257:110972. doi: 10.1016/j.cbpa.2021.110972. Epub 2021 May 1.
On the one hand, oral processing - mastication - is considered a relatively inflexible component of mammalian feed acquisition that constrains instantaneous intake rates. On the other hand, experimental data shows that the level of feed intake affects faecal particle size and hence net chewing efficiency in ruminants, with larger particles occurring in the faeces at higher intakes. Here, we report the effect of an increased feed intake during maintenance (L1), late (200% of L1) and peak lactation (300% of L1) of a consistent diet (hay:concentrates 50:50) in eight domestic goats on various measures of digestive physiology including faecal mean particle size (MPS). Increasing intake led to an increased gut fill, a reduction in digesta retention times, and an increase in faecal MPS (from 0.57 to 0.72 mm). However, this was an effect of the large particle fraction (>2 mm) being disproportionately excreted at higher intakes; if MPS was assessed on the basis of particles below the typical escape threshold (≤1 mm), there was no difference between intake levels. These findings suggest that the effect of intake on the calculated net chewing efficiency in ruminants may rather be an effect of increased large particle escape from the forestomach than a reduced chewing intensity per bolus during ingestion or rumination.
一方面，口腔处理——咀嚼——被认为是哺乳动物获取饲料的一个相对固定的组成部分，限制了瞬时摄食率。另一方面，实验数据表明，采食量的水平会影响反刍动物的粪便颗粒大小，从而影响净咀嚼效率，在较高的采食量下，粪便中的颗粒较大。在这里，我们报告了在维持（L1）、后期（L1 的 200%）和高峰期（L1 的 300%）摄入一致饮食（干草：浓缩物 50:50）时，对八只家养山羊的各种消化生理措施的影响，包括粪便平均颗粒大小（MPS）。增加采食量导致肠道充盈增加，食糜停留时间减少，粪便 MPS 增加（从 0.57 增加到 0.72 毫米）。然而，这是由于高采食量时大颗粒（>2 毫米）不成比例地排出的结果；如果基于小于典型逃逸阈值（≤1 毫米）的颗粒来评估 MPS，则在不同的采食量水平之间没有差异。这些发现表明，采食量对反刍动物计算出的净咀嚼效率的影响可能是由于前胃中大颗粒的逃逸增加，而不是在摄入或反刍期间每口的咀嚼强度降低。
