Effect of heat treatment on antinutrients and precaecal crude protein digestibility in broilers of four tropical crop seeds

Four tropical crop seeds, namely Vigna unguiculata (Cowpea), Mucuna pruriens, Manihot esculenta and Centrosema pubescens were thermally processed for 1 h at 100 degrees C and analysed for their antinutritional factors (ANF). Four hundred and forty-eight 1-day-old broilers were used to determine the effect of heating the seeds on their precaecal crude protein (CP) digestibility. Total phenols, protein precipitable tannins and L-dopa were higher in the mucuna and centrosema seeds and diets than in the vigna and manihot seeds and diets. Phytic acid was of similar occurrence in all the raw seeds. Heat treatment resulted in reduction in all the ANF in the seeds. Precaecal CP digestibility, feed intake and growth rate were significantly (P < 0.01) increased in the heat-treated mucuna and centrosema diets. There was no significant effect on the digestibility of CP, feed intake and growth rate in birds on the vigna and manihot diets owing to heat treatment of the seeds. The results showed that heating improved the nutritive quality of mucuna and centrosema seeds but was not of significant advantage with vigna and manihot seeds when used at levels of up to 150 g kg(-1) in diets.