Abstract :
Attempting to achieve a balance between the supply of and requirements for the major
nutrients implies that demands for major nutrients can be adequately quantified, that the
nutritive value of the consumed diet can be described in similar terms and that the diet
actually consumed by the grazing sheep can be estimated, or at least predicted, from pasture
and animal conditions. Several systems exist for defining the nutrient requirements of sheep
and, whilst there are real differences between them, all are sufficiently accurate to allow
their use in ration formulation and in grazing animal management. Similarly, nutritive
value of feed components can be defined accurately. In grazing sheep, the major difficulty in
balancing the supply of consumed nutrients against nutrient requirements is the estimation
of diet composition and intake. Computer-based decision support tools are a useful aid to
overcoming this problem. It is suggested that since profit derives from animal production
per hectare and not per animal, the balancing of nutrient supply and requirements should
not be attempted on an individual-animal basis.
