Lablab (Lablab purpureus) and lupin (Lupinus angustifolius) seeds as supplements for sheep fed low quality roughage

Abstract

The seeds of lablab (Lablab purpureus) and lupin (Lupinus angustifolius) were investigated as supplements for young sheep. In experiment 1, rumen-cannulated sheep were offered low quality roughage ad libitum alone or supplemented with about 5, 10 or 20 g/kg liveweight whole lupin or lablab seed. Rumen ammonia concentrations were increased by each level of both supplements, and the increases were greater with lupins than with lablab. The pH of rumen fluid was decreased by both supplements, particularly when the higher levels were fed. Dry matter of broken seeds of both legume species rapidly disappeared from synthetic fibre bags incubated in the rumen. Roughage dry matter disappearance from synthetic fibre bags decreased (P<0.05) when 20 g/kg liveweight lupins was fed, and this level of both supplements reduced (P<0.05) roughage intake. Total dry matter intake was increased more by lablab than by lupins, but dry matter and organic matter digestibility tended to be increased to a lesser extent by lablab. Overall, digestible organic matter intake and liveweight gain were increased to similar extents by both supplements. Wool growth was lower (P<0.05) with lablab than lupins, particularly at the highest level of supplementation, suggesting that availability of some amino acids was lower with lablab supplement. In experiment 2, rumen-cannulated sheep were fed low quality roughage ad libitum and supplemented with about 10 g/kg liveweight of either lupin or lablab seed. Lectins and protease inhibitors present in the lablab seed disappeared rapidly from synthetic fibre bags incubated in the rumen. In conclusion the nutritional value of lablab seed as a supplement for sheep fed low quality roughage was similar to that of lupin seed for liveweight gain, but was lower for wool growth.