Meta-analysis of the effect of dietary inclusion of copper on production performance in swine

Background. Copper is a trace element that is involved in various metabolic reactions (cellular respiration, hemoglobin formation and the development of connective tissue), acting with bacteriostatic and bactericidal properties. It can be toxic and excessively excreted into the environment when used at high doses. There are many studies with different levels of inclusion and times of dietary copper supplementation with variable results, generating uncertainty among nutritionists. Objective. To measure the effect of dietary copper inclusion on productive performance in pigs through the use of meta-analysis. Methodology. 24 analyzes were run from 28 scientific articles that included a total of 3908 animals. Under the random effects model, effect size, heterogeneity, meta-regressions and publication bias were determined. Results. The results showed that copper supplementation improved average daily weight gain (+30.61 g/day, p<0.00001), average daily feed intake (+18.726 g/day, p=0.0001), feed conversion (-0.10009 kg/kg, p=0.00003) and feed efficiency (+0.00597 kg/kg, p=0.0052). High values of heterogeneity (>80%) were found in most of the variables evaluated, so meta-regressions were performed with the moderators: duration and level of supplementation, dietary level of crude protein, zinc, vitamins A and E, and number of repetitions. Implications: Optimizing rations with these data maximizes swine performance and mitigates the environmental impact of copper excretion. Conclusion. It was concluded that dietary copper supplementation improved productive performance in pigs and these results are affected by other dietary nutrients.