A meta-analysis of the effects of dietary canola / double low rapeseed meal on growth performance of weanling and growing-finishing pigs

A meta-analysis was conducted to quantify the effect of dietary inclusion rate of canola/rapeseed meal (CRM) on average daily gain (ADG), average daily feed intake (ADFI), and feed conversion in weanling and growing-finishing pigs. The dataset included 37 experiments with 3530 experimental units published from 1987 to 2019. The dietary inclusion rates of CRM ranged from 20 to 400 g/kg for weanling pigs and from 37.5 to 488.4 g/kg for growing-finishing pigs. The impact of feeding CRM was calculated using the Cohen's d (CD) to measure differences among control and experimental means, including the effect of pooled standard deviation of treatments. The overall effect size for ADG and feed conversion in weanling pigs showed no significant impact of CRM inclusion, and linear and quadric weighted regression analyses revealed no significant relationships between CRM inclusion and growth performance in weanling pigs. The ADFI for weanling pigs was significantly reduced by CRM inclusion. In growing-finishing pigs, there was a minor, but significant, reduction in the overall effect size for ADG and feed conversion by CRM feeding, while there was and a tendency towards negative effect on ADFI. There were no significant linear and quadratic relationships between CRM inclusion levels and growth performance in growing-finishing pigs. The data used in the present study suggest that increasing dietary inclusion of low glucosinolate CRM reduced ADFI for weanling, but not for growing-finishing pigs, and had minor or no effect on ADG and feed conversion. It is concluded that CRM can be included as a protein source in nutritionally balanced diets for growing-finishing pigs without adverse effects on growth performance.