The influence of type and timing of protein supplementation on wool growth and protein synthesis in the skin of young Merino sheep

Abstract

There is limited evidence that the response in wool growth resulting from feeding protected protein supplements continues after the feeding has stopped. Feeding such proteins, alternated with traditional supplements, may increase wool growth as much as continuous feeding but at a lower cost. This experiment aimed to determine whether the response to protected protein continued after the sheep were switched to a cereal supplement. Over a 2-month experimental period, 56 weaners (5 months old, weighing 26 kg) were used in a 2 × 2 factorial experiment. Half were fed a diet containing 25% canola meal [partially protected protein with high concentrations of sulfur amino acids (SAA)] mixed with oaten hay, urea, and minerals. The other half were fed the same diet but with lupin seed (highly degradable protein with low concentrations of SAA) replacing the canola meal. Within each of the 2 dietary treatments and in each of 2 months, half of the weaners were fed the diet continuously, the other half were fed the diet for 2 weeks followed by 2 weeks of a barley, oats, hay, urea, and minerals diet. Another group of 8 weaners was fed the oats–barley diet continuously for 2 months. All sheep were fed to lose 35 g liveweight/day. Weaners fed canola meal grew 11% more wool during the experiment and had a higher rate of protein synthesis in the skin than weaners fed lupins. The response to canola meal of wool and skin was the same whether feeding was continuous or alternated with oats–barley, indicating that the benefits from feeding partially protected proteins continues after feeding has stopped.