ABSTRACT

Accurate assessment of the nutritional value of feeds is essential in the formulation of diets and evaluation of different feeds. Gross energy is a poor indicator of the energy available to animals. Faecal energy is the most significant loss from gross energy, and accurate estimates of digestibility are required to produce more accurate measures such as metabolisable energy (ME) and metabolisable protein (MP). However, digestibility of forages is highly variable among or within forage types. As a result, tabulated digestibility coefficients of forages are of little value in diet formulation. This has led to the development of chemical and biological methods to determine forage digestibility. Accurate estimates of both digestibility and energy value of forages are needed for better ration formulation. The composition of feed concentrates is much less variable, and tabulated digestibility coefficients can therefore be used to estimate energy value concentrates. Concentrates

often comprises several ingredients and possible errors in estimated nutritive value and therefore have smaller effects on the nutritive value of the total diet.