Effect of allowance and the rate of adaptation of weaned calves to two brassica types

P.D. Muir, G.J. Wallace, M.W.A. Slay

AgResearch, Poukawa Research Station, P.O. Box 8144, Havelock North, New Zealand

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

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 ėstemmyî brassicas, calves should not be forced into a ėclean upî role on brassicas if the objective is to maximise liveweight gains.

The period of adjustment to brassicas appeared to take four weeks. Over the first four weeks, calves grazing Winfred grew at 1.06 kg per day and calves grazing Wairoa grew at 0.54 kg per day. Over the final two weeks, the pattern reversed and calves grew at 1.50 and 1.94 kg per day on Winfred and Wairoa respectively. Rate of adaptation to brassica may be important consideration if short term grazing/finishing periods are desired.

Keywords: NZSAPAB; allowance; calves; brassicas; Winfred; Wairau

Download abstract in text format
Last Updated 25-01-1997