INFLUENCE OF DIETARY FABA BEANS AND CASSAVA ON PERFORMANCE, ENERGY AND NITROGEN DIGESTIBILITY AND THYROID ACTIVITY OF GROWING PIGS

Abstract

Nutritional value of ground unprocessed faba beans (FB) was studied with 120 growing pigs from 4 wk of age to market weight of 84 kg. Fifteen diets were fed utilizing FB as a partial or total replacement for soybean meal (SBM) in a barley-based diet containing 0, 20 and 40% cassava during the first 9-wk starting phase. During this phase, average daily feed intake (ADF), average daily gain (ADG) and efficiency of feed conversion (EFC) were not significantly altered by partial replacement of SBM by FB (up to 21% of the diet). Supplementation of these diets with L-lysine and DL-methionine did not significantly improve performance. Total replacement of SBM by FB, even when supplemented with lysine and methionine produced significantly lower (P < 0.01) ADF, ADG and EFC although amino acid supplementation significantly improved these diets. Cassava inclusion at up to 40% of the diet did not significantly reduce ADF, ADG or EFC and had no significant effects on blood thyroxine or triiodothyronine levels. Digestibility of energy and nitrogen tended to be reduced as FB levels increased, but the lowered digestibilities could account for only a small proportion of reduced performance. During the finishing phase, partial or total replacement of SBM by FB had no significant effects on EFC. FB diets produced significantly (P < 0.01) lower ADF and ADG. The results suggest that FB supplemented with adequate lysine and methionine may be fed as partial replacement (up to 21% of the diet) for SBM to weanling pigs from 6 kg liveweight.