22 Sep Nutritional requirements of sheep and cattle in spring

~ By Adrian Baker ~

Feeding cattle and sheep is always trickiest at the change of seasons. Autumn and spring involve not only dramatic changes in the forage base, but usually also changes in animal performance.

Nutritional management is reasonably straightforward when forage quality is pretty static: in summer, conserved forage remains constant and standing pasture and crop residues change gradually in quality and availability (assuming no rain); in winter, pasture and forage crops are consistently in a vegetative phase of growth.. At the change of season the situation is completely opposite and livestock have to adapt to dramatic change at a time when requirements are often at a peak for gestation, lactation or growth.

A useful philosophy for managing nutritional requirements is ‘complementary feeding’. This involves assessment of the available feed base (quality and quantity) and the requirements of the class of livestock to be fed. The idea is to then supply the nutrients that will best complement those already available to provide a balanced diet that meets requirements. In pasture based systems, energy is nearly always the first limiting nutrient. Protein is required for rumen microbes to reproduce (and be digested by the host) and it is the next limiting nutrient in summer. Energy and protein often need supplementation in summer and energy and fibre in autumn/winter.

One of the best ways to assess the adequacy of the diet is to be aware of accepted body condition targets, ensure they are met and monitor changes. Another useful tool is monitoring of dung.

It should be kept in mind that livestock take 7-14 days to adopt a novel feeding system and a further 14-21 days for the rumen to adapt to a change in feed base (especially critical is adaptation to grain based feeds). This means that supplementary feeding should begin well before it is required.