Quality of meat from free range chickens as affected by outdoor enrichments and dietary supplementation with n-3 PUFA and antioxidants

This study aimed to evaluate the effects of outdoor enrichments and dietary supplementation with n-3 PUFA and antioxidants on quality and oxidative status of thigh meat belonging to free-range chickens. More in detail, 4 farms were considered: 2 having an outdoor area without pasture (NP) and 2 equipped with an outdoor space with grass and trees (GT). Birds (Hubbard RedJA57, males) belonging to each farm were fed either a control (C) or a supplemented diet with n-3 PUFA and antioxidants (S, 5% linseed, vitamin E, and selenium) and slaughtered at 56d of age. Thighs were collected to evaluate the main meat quality traits (pHu and colour) (n=120; 15/group) and oxidative status (TBARS, carbonyls, and free thiol groups) (n=64; 8/group). Analyses were performed at 0, 3, and 7 d of refrigerated storage (4°C) with the aim of assessing potential differences in the oxidative stability of thigh meat ascribable to the considered effects. A significant effect of the outdoor enrichment was found for the main quality parameters at the beginning of storage as higher pHu along with lower lightness were observed in GT in respect to NP (6.11 vs. 5.92; p<0.001 and 53.6 vs. 54.8; p<0.001, respectively). On the other hand, the dietary enrichment with n-3 PUFA and antioxidants exerted only marginal effects. As for the analyses performed during refrigerated storage, overall, supplementation with antioxidants in chicken fed a n-3 PUFA diet was not able prevent the development of oxidative reactions affecting the lipid and the protein fractions when the outdoor space was enriched. In fact, despite the storage time considered, the highest TBARS and carbonylation levels were measured in “GT-S” and “GT-C” groups, respectively. It is worth noting that enriched diet promoted the occurrence of oxidative modifications affecting the proteins in NP, as depicted by the significantly lower (p<0.05) free thiol groups content detected in “NP-S” group at all storage times. Overall, these findings evidenced that when dietary supplementation with n-3 PUFA is adopted as a strategy to improve the nutritional profile of chicken meat even if antioxidants are also added, their inclusion should be carefully implemented considering the rearing system adopted.