Effects of alternative protein and energy sources on the metabolism and performance of straw fed, pregnant and lactating ewes

Abstract

Fishmeal is a suitable protein source for pregnant and lactating ewes, providing high levels of undegradable protein (UDP) with a high biological value (Sheehan and Hanrahan, 1989). Vegetable protein sources supply a lower proportion of UDP and lack in supply of essential amino acids, but the quality can be improved by heat / chemical treatment and by adding amino acids. It has also been shown that concentrates can be partially replaced by supplementary feed blocks based on soluble sugars and urea with no adverse effects on production and simplifying the feeding regime (Chapple et al, 1996). The objective of the current experiment was to compare the effects of feeding barley based concentrates containing either fishmeal or a protected vegetable protein as the main protein source and the partial replacement of concentrates with a supplementary feed based on soluble sugars and urea (blocks) on the performance and metabolism of pregnant and lactating ewes.