New concepts of feed evaluation for ruminants with emphasis on roughages and feed intake

A possible new feed evaluation system for roughages is discussed based on rumen microbial degradation. It is based on determination of the following characteristics of feeds. The soluble fraction (A) the insoluble but fermentable fraction (B) and the degradation rate of the insoluble but fermentable fraction (C). B and C is determined using nylon bag incubations from generating the formulae p=a+b(1-e(-ct)). Where p=degradation at time (t) and a, b and c are constants. The voluntary intake prediction from degradation characteristic appear to be more accurate than from metabolizable energy or TDN. From these values a feed potential index can be generated which can be used to assess the potential intake and thus potential animal production. It enables feed potential to be matched to animal potential or to develop appropriate animal production systems to match feed potential.