L-CANAVANINE - A NATURAL FEED-INTAKE INHIBITOR FOR PIGS (ISOLATION, IDENTIFICATION AND SIGNIFICANCE)

A major feed-intake inhibitor for pigs is present in seeds of Vicia villosa spp dasycarpa Roth cv Namoi. When the seed is fed for 4 days at only 80 g kg-1 of the diet, it produces a steady diminution in daily feed intake to 25 % or less of their pre-treatment consumption (P < 0.001), after the first feeding. The inhibitor has been isolated and identified as L-canavanine. When analytically pure L-canavanine dihydrochloride is supplied at an equivalent dietary concentration (13.0 mmol kg-1) to that supplied by 80 g kg-1 of Namoi vetch seed, it successfully mimics the response. The response is only observed after the first meal. A review of published literature showed the diversity of animal species exhibiting a feed-inhibition response to canavanine-containing seeds. These reports suggest that this well-documented arginine analogue will be a useful molecule for the study of postingestion feed-intake regulation. An ambient temperature procedure for the large-scale isolation of L-canavanine dihydrochloride is described.