Elwert C, Dove H, Rodehutscord M
1Institut für Agrar- und Ernährungswissenschaften, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany.
Animal. 2008 Jan;2(1):125-34. doi: 10.1017/S1751731107000900.
In a feeding trial with sheep, four animals each were fed one of the three roughages (perennial ryegrass (PR), meadow fescue (MF) and red clover (RC)) or one of the four different mixtures (g/day 250 : 250 : 250, 375 : 75 : 300, 525 : 187.5 : 37.5 and 75 : 525 : 150, respectively) of those three roughages, both with and without the inclusion of 100 g of beeswax-labelled barley. Further, four sheep received a pure lucerne diet to enlarge available data on single species faecal recoveries. All sheep except those fed single-component diets and the 250 : 250 : 250 roughage mix were administered intra-ruminal alkane controlled-release devices (CRD). The aim of the study was to investigate the effect of diet composition on faecal alkane recoveries, and to assess the accuracy of the alkane-based estimate of diet composition and intake based either upon a general set of faecal recoveries across diets or upon dietary recoveries and dietary samples more specifically attributable to individual dietary treatments. For each roughage component independently, the accuracy of diet composition estimates was assessed using linear regression across all diets. The estimates of the proportion of barley were analysed further using mean differences and mean prediction errors. Faecal alkane recovery increased with increasing chain length and was affected by diet composition. RC had a significantly higher faecal recovery for alkanes C25, C27, C29 and C31 than at least one of the other single-roughage diets. When considering mixed diets consisting of PR, MF, RC and barley, the composition of the roughage component significantly affected faecal recovery of all alkanes except C30 and C33. The inclusion of beeswax-labelled barley caused a decrease in faecal recovery of alkanes up to C29. This effect was attributable to the beeswax rather than the barley itself. By contrast, the decrease of faecal recovery of synthetic dosed alkanes from the CRD in diets containing barley, compared with the corresponding diets without barley, was attributable to the supplement itself. It was concluded that synthetic dosed alkanes behaved differently during gut transit from natural alkanes. The proportions of individual dietary components were estimated well over a wide range of proportions. Generally, the more information available, the more accurate the estimates achieved. However, a general set of faecal alkane recoveries and bulked samples of dietary components yielded estimates of diet composition sufficiently accurate for a large number of studies, especially in situations where groups of animals are of concern and not the individual animal.
在一项对绵羊的饲养试验中，将四只绵羊分为一组，分别喂食三种粗饲料（多年生黑麦草（PR）、草地羊茅（MF）和红三叶草（RC））中的一种，或者喂食这三种粗饲料的四种不同混合物（分别为每天250 : 250 : 250、375 : 75 : 300、525 : 187.5 : 37.5和75 : 525 : 150克），两种情况均添加或不添加100克蜂蜡标记的大麦。此外，四只绵羊喂食纯苜蓿日粮，以增加关于单一物种粪便回收率的可用数据。除了喂食单一组分日粮和250 : 250 : 250粗饲料混合物的绵羊外，所有绵羊都安装了瘤胃内烷烃控释装置（CRD）。该研究的目的是调查日粮组成对粪便烷烃回收率的影响，并评估基于烷烃的日粮组成和摄入量估计的准确性，该估计是基于一组通用的日粮粪便回收率，还是基于更具体归因于个别日粮处理的日粮回收率和日粮样本。对于每种粗饲料成分，通过对所有日粮进行线性回归来评估日粮组成估计的准确性。使用平均差异和平均预测误差进一步分析大麦比例的估计值。粪便烷烃回收率随链长增加而增加，并受日粮组成影响。RC的C25、C27、C29和C31烷烃的粪便回收率显著高于至少一种其他单一粗饲料日粮。当考虑由PR、MF、RC和大麦组成的混合日粮时，粗饲料成分的组成显著影响除C30和C33之外的所有烷烃的粪便回收率。添加蜂蜡标记的大麦导致C29及以下烷烃的粪便回收率下降。这种影响归因于蜂蜡而非大麦本身。相比之下，与不含大麦的相应日粮相比，含大麦日粮中CRD合成添加烷烃的粪便回收率下降归因于添加物本身。得出的结论是，合成添加的烷烃在肠道转运过程中的行为与天然烷烃不同。在很宽的比例范围内，单个日粮成分的比例估计得很好。一般来说，可用信息越多，估计就越准确。然而，一组通用的粪便烷烃回收率和日粮成分的混合样本得出的日粮组成估计对于大量研究来说足够准确，特别是在关注动物群体而非个体动物的情况下。
