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While the use of canola meal (CM) as an alternative to soybean meal in broiler diets is welldocumented, there is no information on the utility of this valuable by-product for slow-growing indigenous chickens. This study was, therefore, conducted to evaluate the effects of partially replacing soybean products in a chicken grower diet with graded levels of CM on carcass characteristics, relative organ sizes and meat quality in Potchefstroom Koekoek (PK) cockerels. A total of 175 PK cockerels (342.6 ± 15.2 g body weight, 5 wk old) were randomly allocated to 25 pens. Five isonitrogenous and isoenergetic grower diets containing 0, 3.75, 6.25, 8.75, and 17.5% of CM were then randomly allocated to the pens (experimental units). After 12 wk of feeding, chickens were slaughtered to measure carcass traits, size of internal organs and meat quality traits. There were no effects of graded levels of CM on carcass weights. Wing weight increased quadratically [y = 6.27(±0.23) + 0.23 (±0.063) x–0.009 (±0.0003) x²; R² = 0.28] in response to incremental levels of dietary CM. Drumstick, vertebrae, liver, and small intestine weights linearly increased (P < 0.05) in response to incremental levels of dietary CM. Redness (a*), initial meat pH (pHo), and shear force linearly increased (P < 0.05) but lightness (L*) and water holding capacity decreased with an increase in CM inclusion levels. However, there were no significant linear and quadratic trends for yellowness (b*), ultimate pH (pHu), drip loss, and cooking loss in response to incremental levels of CM. There were also significant quadratic trends for mineral contents of the meat with the exception of iron (Fe). It can be concluded that inclusion of CM in place of soybean products had no negative impact on carcass traits, organ size and meat quality traits of indigenous PK chickens. [ABSTRACT FROM AUTHOR]

• Seaweeds are functional feed ingredients with putative growth-stimulating and meat quality-enhancing effects. • Effectiveness of exogenous fibrolytic enzyme pre-treatment in enhancing seaweed feed value was investigated. • Fibrolytic enzymes did not improve feed intake, physiological parameters, and meat quality in broiler chickens. Seaweeds are functional feed sources that contain biocompounds with growth-stimulating, antimicrobial and meat-enhancing properties. However, the presence of non-starch polysaccharides such as cellulose, hemicellulose, pectin and xylan may limit its utilization in broiler diets. Thus, this study evaluated the effects of pre-treating dietary green seaweed (Ulva sp.) with a fibrolytic enzyme mixture on physiological and meat quality parameters of Cobb 500 broiler chickens. Three hundred and thirty, two-week old male chicks (318.9 ± 16.12 g live weight) were evenly and randomly placed in 30 replicate pens (experimental units) to which five isonitrogenous and isoenergetic diets were randomly allotted. Experimental diets were commercial grower and finisher diets containing seaweed pre-treated with a fibrolytic enzyme mixture of cellulase, hemi-cellulase, arabanase, β -glucanase and xylanase, at the rate of 0 (EZ0), 2.0 (EZ20), 5.0 (EZ50), 7.5 (EZ75) and 12.0 g/kg (EZ120). Growth performance, blood indices, visceral organs, and carcass and meat quality parameters were determined. No week × diet interaction effect (P > 0.05) on average weekly feed intake (FI), body weight gain (BWG), and feed conversion efficiency (FCE) was observed. Neither linear nor quadratic trends (P > 0.05) were observed for overall FI, growth performance, haematological and serum biochemical parameters as well as visceral organ weights in response to incremental levels of fibrolytic enzyme pre-treatment of seaweed. However, there was a linear increase in hot [R2 = 0.176, P = 0.033] and cold [R2 = 0.164, P = 0.040] carcass weights in response to increased enzyme pre-treatment rates. Breast meat lightness measured immediately after slaughter (L * i) linearly decreased [R2 = 0.147, P = 0.022] as enzyme levels increased. Diets with enzyme-treated seaweed promoted higher (P< 0.05) carcass weights compared to the untreated seaweed-containing control diet. It was concluded that pre-treatment of seaweed meal with an exogenous fibrolytic enzyme mixture did not improve growth performance, blood parameters, and meat quality traits in broiler chickens. An optimum fibrolytic enzyme treatment level for seaweed could not be determined, suggesting a need to investigate levels beyond the maximum treatment level of 12 g/kg used in this study. [ABSTRACT FROM AUTHOR]