Characterization of Digitaria swazilandensis Stent and Brachiaria humidicola (Rendle) Schweickt swards during continuous grazing by zebu cattle in French Guiana

Abstract

A trial with two tropical forage grasses, Digitaria swazilandensis Stent and Brachiaria humidicola (Rendle) Schweickt, took place during 1989 and 1990, in order to test the continuous grazing system in French Guiana with zebu Brahman bulls. Herbage production (aerial dry matter) varied with rainfall; the leaf/stem ratio was higher during dry season, such as the leaf weight per surface unit. Concerning the descriptive parameters of the sward, D. swazilandensis had the same behaviour in dry season than a temperate grass, with a high correlation between leaf area index (LAI) and the sward height. This correlation was observed in dry and wet seasons with B. humidicola. This species was more productive and less sensitive to water deficiency than D. swazilandensis, but its nitrogen content was lower. However, the same animal performances were obtained with the two species. Investigations about continuous grazing during the dry season should be completed with stocking rate adjustements and the utilisation of forages reserves.