Effect of Substituting Soybean Meal with Cowpea (Vigna unguiculata WAL) Supplemented with Natural Plant Charcoals in Broiler Diet on Growth Performances and Carcass Characteristics

Abstract

A total of 280 unsexed broiler chicks, 21 days-old and weighing 580 g on average were randomly distributed into 28 experimental units of 10 birds each. Seven experimental diets containing respectively 0% (T0 control), 20% raw cowpeas (T1), 20% raw cowpeas + 0.2% of Canarium charcoal (T2), 20% raw cowpeas + 0.2% maize cob charcoal (T3), 20% cooked cowpeas (T4), 20% cooked cowpeas + 0.2% Canarium charcoal (T5) and 20% cooked cowpeas + 0.2% maize cob charcoal (T6) were each fed to 4 experimental units in a completely randomised design. The T3 and T6 rations containing respectively raw and cooked cowpeas supplemented with maize cob charcoal were the most consumed (P<0.05). Birds fed T1 with raw cowpea (1287g) and T2 fed with raw cowpea supplemented with Canarium charcoal (1280 g) recorded the lowest weight gain, with the control birds (1536 g) and birds fed T6 containing cooked cowpea supplemented with maize cob charcoal (1490 g) recording the highest body weight gain. Feed conversion ratio (FCR) was significantly poorer (P<0.05) for the birds fed raw cowpea supplemented with Canarium charcoal (3.23), those on the control diet without cowpea recorded the best FCR (2.74). There was no significant difference among treatment groups for carcass yield and the lowest (P<0.05) liver and pancreas relative weight recorded for the birds on the cooked cowpea supplemented with charcoals diets was not significantly different from that of control birds. The lowest gizzard relative weight was recorded with control birds as compared with all other groups. The intestine density (weight/length) was significantly lower (P<0.05) with raw cowpea supplemented with Canarium charcoal (0.19 g/cm), and the highest recorded with cooked cowpea (0.27 g/cm) and control diet (0.25 g/cm).