Quantification of the effects of castration on carcass and meat quality of sheep by meta-analysis

• Economically important differences between intact rams and wethers were quantified.
• Rams present greater average daily gains and loin muscle areas.
• Wethers have greater dressing percentages and backfat thickness.
• Compared to wethers, meat from rams is less tender.

After an extensive literature search, meta-analytic techniques (fixed effect, random effects and hierarchical Bayesian models) were applied to numerically describe sizes and precision of effects caused by castration of intact rams on several performance, carcass and meat quality response variables. According to random effects models, rams presented greater (P < 0.05) average daily gain, loin muscle area (leaner carcasses) and instrumental meat tenderness (more tough), with lower feed conversion ratios, dressing percentages and backfat thickness (less carcass fat) compared to castrates. These results could be applied in further strategies on the use of castration in male sheep.