Meta-regression of the relationship between dietary 18C n-3 concentration and enrichment of n-3 fatty acids in liver and breast muscle of broiler chickens

The long-chain n-3 fatty acids (FA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have human health benefits, and many experiments have investigated the ability of plant n-3 sources to enrich n-3 FA in broiler meat. A meta-regression was conducted to evaluate the relationship between dietary 18-carbon n-3 FA content and the deposition of EPA, docosapentaenoic acid (DPA), and DHA in broiler breast and liver tissue. Bivariate regression of total diet 18-carbon n-3 and tissue FA profile was modeled with the random effect of experiment and the partial R² was calculated. Increasing 18C n-3 FA in the diet quadratically increased the log₁₀ concentration of all n-3 FA in breast tissue. The strongest relationship was found for breast alpha-linolenic (partial R² = 0.55), followed by EPA, DPA, and DHA (partial R² = 0.20, 0.14, and 0.05). Liver enrichment of EPA, DPA, and DHA (all partial R² > 0.43) and EPA + DHA (partial R² = 0.55) was quadratically related to dietary 18C n-3 FA, while liver EPA + DPA + DHA (partial R² = 0.43) was linearly related to dietary 18C n-3 FA. In both breast and liver, the plateau in tissue enrichment was more apparent for DHA than EPA, with DPA being intermediate. A linear plateau model fit the data with a break point for enriching EPA and DHA in breast muscle at 22.4 and 17.9 g/kg of 18C n-3 FA in the diet, respectively. Enrichment of long-chain n-3 FA in broiler chickens was saturable, with little justification for feeding beyond approximately 20 g/kg 18C n-3 FA.