Effects of intraperitoneal injections of DL-methionine on the voluntary intake and wool growth of sheep fed sole diets of hay, silage and pasture differing in digestibility

Abstract

SUMMARYPenned Romney wether sheep were fed ad libitum diets of untreated silage and hay made from the same pasture (Expt 1), untreated silage (Expt 2), and high quality fresh pasture (Expt 3). Voluntary intake and wool growth were measured. In each experiment half of the sheep were given intraperitoneal injections three times per week which supplied the equivalent of 1·03 g DL-methionine/day.Relative to silage in Expt 1, hay increased voluntary dry matter intake, depressed apparent nitrogen digestibility and increased wool growth. Methionine supplementation increased voluntary intake and wool growth with animals fed on hay or silage in Expt 1 and with those fed on silage in Expt 2, but had no effect on either variate with the diet of fresh pasture.Wool sulphur content, measured in Expts 2 and 3, was increased by methionine supplementation, and it was calculated that 34 and 15% respectively of the sulphur administered as methionine was recovered in the wool.The effects produced by methionine supplementation in this work are compared with those produced from different forms of post-ruminal amino acid supplementation in sheep fed a variety of diets. Factorial estimates of the requirements for sulphur of sheep and cattle in different physiological states have been calculated, and are discussed in relation to results of trials involving supplementation with sulphur-containing amino acids.