Growth responses of young Merino wethers to ad libitum feeding of oat grain mixed with either lupin seed or a urea solution

Abstract

Groups of 10 Merino weaners or hoggets were offered ad libitum 1 of 5 grain mixtures: oats alone (9.1% crude protein, CP), oats mixed with lupins (CP 12 or 15%), and oats sprayed with a urea solution to increase total nitrogen to an equivalent of 12 or 15% CP. In experiment 1, each grain mixture was fed with 10% milled cereal hay to sheep in pens for 98 days; in experiment 2 the sheep grazed wheat stubble for 84 days. In experiment 1, the liveweight gains of weaners and hoggets fed the lupin or urea mixtures were greater by 53-69% and 58-120¦/o, respectively, than the daily 9.4 and 54.1 g/head gained on oats alone (P< 0.05). In experiment 2, liveweight gains of sheep fed these mixtures were, with 1 exception, greater by 95-1 54% than the 69.0 and 58.3 g/head gained daily by sheep fed oats alone (P< 0.05). Addition of urea to oats at the higher level (15% CP) tended to depress intake and liveweight gain, compared with the 12% CP level, and the effect was greater among hoggets. Wool production paralleled feed intake and liveweight gain. It is concluded that the daily growth rates of 90 to 130 g/head resulting from treatment of oats with up to 1.5% urea can be similar to those from oat-lupin mixes of equivalent CP (daily 85-150 g/head).