Mupangwa et al., 2003. Livest. Res. Rural Dev., 15 (5)

The rumen degradability of nitrogen from Cassia rotundifolia (Cassia), Lablab purpureus (Lablab) and Macroptilium atropurpureum (Siratro) was investigated by the in sacco technique using three rumen fistulated Friesian steers. The legumes were harvested at 8, 14 and 20 weeks of growth and either sun or oven dried before being incubated for 6, 12, 24, 48, 72, 96 and 120 h.

The quickly degradable nitrogen content of the legumes was different at similar stages of growth. Lablab, at 8 weeks of growth, had a higher content of quickly degradable nitrogen, irrespective of drying methods, compared to cassia and siratro which also differed. However, at 14 weeks of growth, sun dried cassia had quickly degradable nitrogen content higher than lablab and siratro. Oven drying reduced the quickly degradable nitrogen content of cassia compared to that of lablab and siratro. The rate of degradation of the slowly degradable nitrogen fraction was greater for siratro, than either cassia, or lablab. Oven drying reduced the rate of degradation at 8 weeks of growth but had no effect in forages harvested at 14 and 20 weeks of growth.

It was concluded that legumes provide variable amounts of degradable nitrogen that is dependent on species, stages of growth and drying treatments.