Factors limiting the intake by sheep of the tropical legume, Calopogonium mucunoides

Abstract

Sheep were studied to determine whether their low intake of organic matter (400-500 g/day OM) of calopo (Calopogonium mucunoides) was due to toxic properties of the plant, factors that affect its 'acceptability', or to the mineral status of the legume. Practical methods of increasing intake of the harvested plant were also investigated. The low intake by sheep of calopo was not due to its toxicity since supplementation with 500 g/day of ground calopo via the ruminal fistula did not depress voluntary consumption of lucerne hay more than when an equivalent amount of siratro was given. Treatment of the plant with the 'taste-modifiers' monosodium glutumate (2% dry matter fed) and molasses (5%), or with sodium hydroxide 4% w/w or its molar equivalent of potassium hydroxide was associated with an immediate and sustained increase in organic matter intake of about 40%. This intake is similar to that of other tropical forages with similar digestibilities. The taste or odours of the plant therefore appear to limit intake. The low sodium (0.03%) and marginal potassium (0.55%) content of calopo induced a deficiency of these elements in the animal which did not affect intake in the short term. Treatment with molasses had the advantage of supplying extra potassium and energy.