Comparative assessment of physico-chemical and fatty acid profiles of Moroccan Beldi and ROSS 308 chickens.

This study investigated the effects of genotype, rearing system, and slaughter age on meat quality by comparing Moroccan indigenous Beldi chickens with commercial ROSS 308 broilers, with the aim of identifying strategies for optimizing nutritional properties. A total of 400 birds (200 Beldi and 200 ROSS) were reared either in intensive (10 birds/m², commercial diet) or extensive rearing systems (4 birds/m², outdoor foraging). ROSS chickens reared intensively were slaughtered at 4, 5, and 6 weeks, whereas the other experimental groups were slaughtered at 12, 18, and 24 weeks. Physico-chemical composition (dry matter, crude protein, ash , and fat content, and fatty acid (FA) profile, pH, cooking loss, color, and tenderness) were analyzed. Each experimental group included 100 birds, which were further divided into two subgroups of 50 birds each, serving as biological replicates. Data were analyzed using a mixed linear model with repeated measures on muscles. Subgroup-level analyses showed no significant differences, allowing data to be pooled for group-level comparisons. Results showed that Beldi chickens exhibited higher dry matter (28.25 vs. 25.48 %; p < 0.001) and crude protein (24.20 vs. 18.86 % FM; p < 0.001), but lower fat content (1.77 ± 0.10 % vs. 1.92 ± 0.09 % FM; p < 0.001) than ROSS chickens. Particularly in the extensive system and at later slaughter ages, Beldi chickens exhibited higher pH values across both the breast and thigh and firmer meat with higher shear force values. Under the intensive system, chicken meat was characterized by higher tenderness, lightness (L*), and yellowness (b*), but reduced redness (a*) and cooking loss, compared to the extensive system. The fatty acid (FA) profile also varied according to these factors, with meat from Beldi chickens characterized as healthier with lower SFA and MUFA content, but higher PUFA content. Moreover, according to health indices, Beldi chickens were characterized by higher PUFA/SFA, desirable fatty acids (DFA), essential fatty acids (EFA), and LA/ALA, and a lower thrombogenic index (TI) than ROSS chickens. Meat from the extensive system was characterized by higher total SFA and MUFA and lower PUFA. In summary, Beldi chickens, particularly when reared under extensive systems, produced meat with enhanced nutritional quality, whereas ROSS broilers provided more tender meat. Tailoring rearing strategies to each genotype's strengths can help optimize meat quality and meet diverse consumer preferences.