ABSTRACT
Canola meal (CM) is a potential alternative dietary protein source for indigenous chickens but its utility may be limited by anti-nutrients such as fibre and phytochemical compounds. This study, therefore, explores the effects of replacing soy-based feedstuffs (SB) with graded levels of CM on apparent nutrient digestibility, growth performance and haemo-biochemical parameters in Potchefstroom koekoek (PK) cockerels. Five isonitrogenous and isoenergetic diets were formulated by replacing 0 (CM), 3.75 (CM1), 6.25 (CM2), 8.75 (CM3) and 17.5% (CM4) of SB with CM. One hundred and seventy-five cockerels (342.6 ± 15.2 g live weight, 5 weeks old) were evenly distributed into 25 replicate pens to which experimental diets were randomly allocated. Feed intake, apparent nutrient digestibility, weight gain, feed conversion ratio and protein efficiency ratio (PER) were determined. Blood was collected for serum and haematological analysis at 16 weeks of age. There was a significant quadratic trend [y = 2.56 (± 0.067) + 0.04 (± 0.019)x - 0.002 (± 0.0010)x2] for average weight gain from which an optimum canola inclusion level was calculated to be 7.8%. Neutrophils linearly increased (P < 0.05) with CM levels, but there were no significant linear and quadratic trends for serum biochemical components with the exception of total calcium and triglycerides, which decreased linearly in response to incremental levels of CM. However, feed intake, feed utilisation efficiency, growth performance and serum biochemistry parameters were not affected by experimental diets. Based on weight gain response, it was concluded that replacing soy-based dietary ingredients with CM in poultry diets up to 7.8% does not result in adverse effects on diet utilisation, growth performance and health status of PK cockerels.