Growth of young Merino sheep grazing cereal stubbles and supplemented ad libitum with oats, of different crude protein contents, sprayed with various amounts of urea

Abstract

In 2 experiments on cereal stubble, growth responses by Merino hoggets and Merino weaners to ad libitum supplementation with oat grain sprayed with a urea-ammonium sulfate solution were examined. In each experiment, 3 batches of oats of different crude protein(CP=7.8,9.3, 11.4 and 7.1, 10.1, 12.5% w/w) were treated with different amounts of urea (0.55-3.2% w/w) and the feed was offered to groups of 10 hoggets or 7 weaners for 70 days and 100 days respectively. The growth of Merino wether weaners grazing wheat stubble was significantly increased from 86 g/sheep.day to 116 g/sheep.day by adding urea to supplements of low protein (7%) oats. The intake of low protein oats sprayed with urea was decreased when urea was added at a level making up 3% of the supplement. Daily growth rates (132-152 g/sheep) of weaner sheep fed oats of 10% and 12.5% crude protein were not significantly different. The addition of urea to these oats did not produce significant additional growth responses. There was no effect on hogget daily growth rate (average = 160 g/sheep) of CP, of the base oat, or of treatment of the oat with a urea-ammonium sulfate mixture.