Assessment of the nutritive value of the seeds of some tropical legumes as feeds for ruminants

Samples of eight tropical legume seeds (Macroptilium lathyroides (Phasey bean), Centrosema pubescens (centro), Pueraria phaseoloides (Puero), Calopogonium mucunoides (Calopo), Leucaena leucocephala (Leucaena), Stylosanthes guanensis (Stylo), Macroptillium atropurpureum (siratro) and Clitoria ternatea (Blue pea) from Tanzania were evaluated using percent nitrogen (protein) content, in vitro gas production, dry matter (DM) degradability and defaunating ability. Clitoria ternatea seeds had the highest %N (7.07) while Centrosema pubescens had the lowest (3.52). The ranking of the seeds in terms of percent protein content was as follows: Clitoria ternatea>Pueraria phaseoloides> Calopogonium mucunoides>Stylosanthes guianensis> Macroptillium atropurpureum>Leucaena leucocephala> Macroptilium lathyroides> Centrosema pubescens. Species and PEG had significant effect on in vitro gas production. Centrosema pubescens produced significantly highest volume of gas (55ml) while .Stylosanthes guianensis produced the lowest volume of gas. (29ml).The ranking of the seeds in terms of gas production was: Centrosema pubescens >Macroptillium atropurpureum> Macroptilium lathyroides > Leucaena leucocephala >Pueraria phaseoloides > Calopogonium mucunoides > Clitoria ternatea > Stylosanthes guianensis.. There was increase in gas production on addition of PEG only in Stylosanthes guianensis (P<0.05). The seeds had high degradability. Leucaena leucocephala and Stylosanthes guanensis seeds were the least degraded while Centrosema pubescens was the most degraded. The ranking of the seeds based on nylon bag degradability was: Centrosema pubescens> Pueraria phaseoloides > Clitoria ternatea > Macroptilium lathyroides > Macroptillium atropurpureum> Calopogonium mucunoides > Leucaena leucocephala> Stylosanthes guianensis. There was a high positive correlation between in vitro gas production and nylon bag degradation (r=0.87). Only seeds of Calopogonium mucunoides and Clitoria ternatea.had defaunating activities. It is concluded that the seeds of tropical legumes have potential as feed supplements for ruminants as they have high digestibility and are rich in nitrogen. Clitoria ternatea and Calopogonium mucunoides appear to have potential as defaunating agents.