Sclerocarya birrea caffra nut meal as a substitute to soyabean meal: Effects on growth performance, feed intake and utilisation and viscera macromorphometry of blue-helmeted guinea fowl

Abstract

Imported soyabean meal (SBM) is the major dietary protein (DP) source for the sub-Saharan African poultry industry making poultry production costly. Therefore, alternative locally available DP sources are required. We evaluated the potential of locally available Marula nut meal (MNM) to substitute SBM in Guinea fowl (GF) diets by determining its effects on growth, feed intake (FI) and utilisation and viscera macromorphometry. Five grower diets wherein, on a CP basis, MNM substituted SBM at 0, 25, 50, 75 and 100% were formulated. Thirty-eight 4-week-old keets (n = 7 – 8), each individually housed in a cage, were randomly assigned to grower diets, and fed for 5 weeks and then transferred to corresponding finisher diets and fed for 3 weeks. Induction and weekly body mass, daily FI, and terminal body mass (TBM), body mass gain (BMG), average daily gain (ADG) and feed conversion ratio (FCR) were determined. On slaughter, viscera masses, small and large intestines lengths, tibiae and femora indices were determined. In week 2 of the grower phase GF fed diet 3 (50% MNM CP) had the highest weekly BMG and ADG (P < 0.05) and in week 5 GF fed diet 5 (100% MNM CP) had the highest FI (P < 0.05). Dietary MNM did not affect the GF's BMG, ADG, FI and FCR during weeks 1, 3 and 4 of the grower phase. In week 3 of the finisher phase GF fed diet 3 (50% MNM CP) had the highest (P < 0.05) FCR. Dietary MNM had no effect (P > 0.05) on the trial BMG, ADG and FI of the GF but GF reared on grower and finisher diets 3 (50% substitution of SBM CP) had the highest (P < 0.05) FCR. MNM had no effect on tibiae and femora masses, lengths, and mass: length ratios and viscera macromorphometry of the GF. We conclude that MNM can, on a CP basis, substitute SBM, in GF grower and finisher diets at 25%, 75% and 100% without compromising growth, FI and utilization and viscera of GF.