Effects of raw and treated jack beans(Canavalia ensiformis) and of canavanine on the short-term feed intake of chicks and pigs

Abstract

SUMMARYFour experiments were conducted in the Yucatán, Mexico, in 1991 and 1992 to study feed intake in 24 h trials with chicks and pigs fed diets containing either raw or treated jack beans or conventional diets with added canavanine.Feed intake of chicks in the first hour was markedly reduced and feed intake of pigs was severely reduced when raw jack beans (300 g/kg for chicks, 250 g/kg for pigs) were included in their diets. Feed intake of pigs diminished to a greater extent than that of chicks when treated beans (300 g/kg) were included in the diet. Short-term feed intake of chicks was not affected when canavanine (3·5 g/kg) was added to a sorghum-soyabean diet. However, pigs showed a large drop in feed intake when canavanine was added to a maize-soya diet at only 0·8 g/kg. It was concluded that in both species the anti-nutritional factors in jack beans cause a rapid reduction in feed intake which precedes a depression in growth rate. The initial feed intake depression in pigs could be partly attributed to canavanine remaining in the jack beans after treatment. In the chicks' case, however, rejection of a diet containing treated jack bean was due to anti-nutritional factor(s) other than residual canavanine.