THE USE OF LIVEWEIGHT-GAIN TRIALS FOR PASTURE EVALUATION IN THE TROPICS

Two methods of measuring the liveweight gain of cattle on sown pastures are described in a 15 ac grazing trial. During the first 12 months of grazing, stocking rate was varied within and between pasture species. In the remaining 21 months, stocking rate was maintained at the same level between all pastures, but varied with the overall seasonal changes in grass availability. The relative merits of the two methods are discussed, and it is concluded that the trial using the same stocking rate on all species offered the more effective and practicable method of comparing pasture production differences of the order 30–50%.
The results showed significant improvements in liveweight gain in the latter 21 months of the experiment, resulting from the inclusion of a legume, Centrosema pubescens in a Hyparrhenia rufa sward, and from the use of Hyparrhenia rufa rather than Panicum maximum in association with Centrosema pubescens . The ability of unfertilized ley pastures to produce over 300 lb/ac of liveweight gain in favourable years was clearly demonstrated.