A thesis submitted in partial fulfilment of the requirement for the Degree of Master of Science

Thesis (M.Sc.) - Asian Institute of Technology, 1991

The early summer yield of six tropical grasses, Brachiaria mutica, Panicum maximum, Andropogon gayanus, Panicum coloratum, Brachiaria decumbens and Setaria sphacelata, was studied in the first year of their establishment in association with Centrosema pubescens. A 6*6 Latin Square design was use d to test the performance of the six grasses. Plots were harvested three times: 9 April, 27 May and 25 June 1991. The second and third harvest were used to estimate early summer yield. There were no significant differences among the cumulative yields of dry matter on an area basis although B.decumbens and P.coloratum stood out in the field due to their much higher plant population. Yields fell within the range 300-800 kg DM /ha. The statistical analysis for grass yields at all harvests were determined by high coefficient of variation (in the range 50-70 %) due to mainly low and variable plant populations. When the data were analysed on a per plant basis, values obtained for P.maximum and S.sphacelta were indicative of the observed vigour for their performance in the field . Statistically significant differences were measured in the nitrogen content of the grasses at the third harvest but in terms of ruminant animal production these differences are not relevant. Nitrogen contents fell within the range 1.00 to 1.25%; these levels are sufficient to maintain positive nitrogen balance in cattle during the early summer period. Legume contribution was not appreciable at the time of the study since only seven months time had elapsed since its establishment in the cool pa rt of the dry season. A full evaluation of the grasses requires at three season of measurement during which time population will increase and the legume component contribute nitrogen to the mixed sward.