This study investigated effects of dietary supplementation with graded levels of DL-methionine and phytase enzyme on performance and carcass characteristics of broilers fed diets containing high levels of marula (Sclerocarya birrea A. Rich.) seed cake (MSC), an alternative locally available feedstuff. Two hundred and seventy 28-day-old broilers were ad libitum fed treatment diets in a 3 x 3 factorial design involving 2 concurrently run experiments (Exp. 1 and 2; 135 birds each) in which each had 3 MSC levels (0, 200 and 300 g/kg) and 3 levels of ameliorant (DL-methionine or phytase) for 16 days. Each treatment had 3 replicate pens of 5 birds. Dietary MSC decreased body weight gain (BWG; P < 0.01), feed conversion efficiency (FCE; P < 0.05) and weights of live birds at slaughter (P < 0.01), heart (P < 0.05), neck (P < 0.05) and feet (P < 0.01) in DL-methionine supplemented broilers. Also, it decreased BWG (P < 0.01), feed intake (FI; P = 0.05) and weights of live birds at slaughter (P < 0.001) in phytase supplemented birds. There was no significant ameliorative effect (P > 0.05) of DL-methionine, phytase, MSC x DL-methionine and MSC x phytase interactions on all performance parameters and carcass characteristics, except for the tendency of phytase to decrease gizzard weight (P = 0.054) and a significant MSC x phytase interaction (P < 0.05) for this parameter. MSC increased weights of the gizzard (P < 0.001) and intestine (P = 0.001) in DL-methionine supplemented broilers and weights of the gizzard (P < 0.001), neck (P < 0.01) and feet (P < 0.01) in phytase supplemented birds. In conclusion, MSC deleteriously affected broiler performance and carcass characteristics which could not be ameliorated through DL-methionine or phytase supplementation

Keywords: marula (Sclerocarya birrea) seed cake, anti-nutritional factors, DL-methionine, phytase enzyme, broiler chicken, feed intake, body weight gain, feed conversion efficiency, carcass characteristics