Abstract

Groups of 10 Friesian bull calves averaging 142 kg were offered Winfred forage brassica (62% leaf) at allowances of 3, 6, 9, 12 or 15% of bodyweight (BW) for 6 weeks. Similarly, groups of 8 Friesian bull calves averaging 150 kg were offered Wairoa forage brassica (67% leaf) at allowances of 3, 5, 7, 9 and 12 % of bodyweight. Calves were weighted weekly and offered fresh allowances each week. The two experiments were conducted between January and March of the same year but were not run concurrently. There was a significant effect (P<0.01) of allowance on liveweight gain for calves offered Winfred, with calves on the lowest allowance (3% of BW) growing at 0.90 kg/day, compared to 1.20 kg/day for calves grazing the other four allowances. Calves grazing the low allowance (3% of BW) utilised 77% of the total crop, but only 43% of the stem. On the other hand, calves grazing the low allowance of Wairoa utilised 90% of the total crop and 72% of the stem without suffering a liveweight penalty. There was no effect of allowance of Wairoa on calf growth rate and overall, calves on Wairoa grew at an average of 1.03 kg/day. Choice of a leafy type of brassica maybe important if the objective is a high degree of utilisation coupled with good animal performance. Alternatively, on

PD, Muir, GJ Wallace, and MWA Slay

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 257-260, 1995