Abstract

Strategies for adapting cattle from pasture to brassica diets were compared. Groups of 20 Friesian weaner bulls were offered three diets at a fixed daily allowance of 12% of liveweight as drymatter on offer, for a six week period during February and March 1994. Animals continuously grazing pasture and a Wairoa brassica crop were compared to a group receiving half their allowance as pasture and half as Wairoa brassica, in separate night and day breaks. Unfasted animal liveweights were measured each week for the duration of the trial. Utilisation and botanical compositions were estimated from quadrat harvests to ground level before and after grazing. Liveweight differences among treatments at the start (overall mean 178.9 kg) and at the finish of the trial (overall mean 207.4kg) were non statistically significant (P>0.09), although growth paths differed between treatments. Both groups receiving brassica initially lost weight, the effect being most pronounced after the first week when growth rates were -0.28 kgLW/day in brassica, 0.36 kgLW/day in pasture, and -0.77 kgLW/day in the mixed diet (P<0.05). During the final week of the trial growth rates were 1.12 kgLW/day, 1.86 kgLW/day and 1.44 kgLW/day for brassica, pasture and mixed diets respectively (P<0.05). Overall average growth rates did not differ significantly (P>0.10). Large areas of crop will be required to fully realise the benefits of short term rapid growth rates.

PW, Woods, JN Couchman, and HA Barlow

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 251-254, 1995