Abstract
Factors affecting the relationship between the in vivo and in vitro digestibility of forage crops in Uganda were examined. The in vitro technique was used to estimate the dry matter digestibility of a range of grasses and legumes harvested at regular intervals during the rainy season at Kabanyolo. There were shown to be marked effects of Ca wily, genus, species and variety, and of time of harvest, on dry matter digestibility. Grasses characteristic of the natural grasslands of Uganda, e.g. Themeda, Hyparrhenia, Cymbopogon, were found to have lower digestibilities at most stages of growth than 'improved' or 'planted' types, e.g. Chloris, Setaria, Brachiaria Panicum, and to have a lesser rate of decline in dry matter digestibility with advancing maturation. The digestibility of the improved fertilized grasses, and the changes in digestibility, were similar to those observed for temperate species. The legumes had a generally lower dry matter digestibility during the early stages of growth and a lower rate of decline in digestibility with time. Species with differences in in vitro digestibility among the grasses were of sufficient magnitude to recommend the use of the in vitro technique as a selection index for forage quality.
