Effect of Slaughtering Age in Different Commercial Chicken Genotypes Reared According to the Organic System: 1. Welfare, Carcass and Meat Traits

Abstract

The carcass and meat quality of three different commercial chicken genotypes reared according to the organic system and slaughtered at two different ages (70 and 81 days) were compared. The used genotypes were Naked Neck (CN1), Kabir (KR4) and Ross 308 (R). All animals were raised in the facilities of a big Italian company, in production units of 3000 birds. Before slaughtering, plumage conditions, foot pad dermatitis as well as qualitative traits of carcasses, such as skin damage and the presence of breast blisters, were registered (n=50). Naked Neck birds showed the best plumage conditions at both ages; the other genotypes had similar body conditions showing a dramatically worsening at the end of rearing cycle (81 days), mainly at breast level. The carcass conformation showed differences mainly for the CN1 genotype, which was more slender with higher proportions of head, neck and legs; thus, ready-to-cook-carcass yield was lower. The meat of CN1 chickens showed lower levels of lipids, pH and brightness values, but higher index of redness. Ross 308 genotype showed a bad welfare status even at 70 days, confirming that the rearing of this strain should not be permitted in organic systems. In conclusion, this study indicates that genotype deeply affects performance, welfare and qualitative characteristics of meat. Regarding the slaughtering age, although the inconsistency of European Commission rules which authorise the reduction of slaughtering age in less mature strains, at 70 days chickens show higher feed efficiency and thinness of carcass and meat.

Feed efficiency, growth performance, and carcass characteristics of a fast- and a slower-growing broiler hybrid fed low- or high-protein organic diets

“…As expected from hybrid standards, the fast-growing Ross birds demonstrated higher daily weight gain than the slow-growing Rowan Ranger birds, resulting in higher body weight at slaughter and higher carcass weight. These results confirm previous findings on growth performance in fast-and slowgrowing hybrid birds (Castellini et al 2002;Fanatico et al 2005;Dal Bosco et al 2014). For the fast-growing hybrid Ross, the average growth rate was lower then what is described in the performance objectives in the ROSS manual (Aviagen 2014), possibly because of the lower protein quality in organic diets compared to the conventional diets used in the ROSS manual performance evaluation.…”

Comparison of qualitative and quantitative properties of the wings, necks and offal of chicken broilers from organic and conventional production systems

“…However, Somsen et al cantly different *P < 0.05, **P < 0.01 (2004) reported that the average yield of chicken giblets was 4.36% at an average live weight prior to slaughtering of 1898 g in the case of conventional broilers. Dal Bosco et al (2014) affirmed rapid muscular-skeletal development in fast-growing birds as well as excessive development of the cardiovascular system in slow-growing chickens; in line with these observations, OC showed higher heart percentages than CC. The gizzards of OC were heavier and yielded more due to differences in feeding (access to grassy paddock) which could include various kinds of forage, insects, worms and sand particles.…”

Adaptation to organic rearing system of eight different chicken genotypes: behaviour, welfare and performance

“…On the basis of our previous studies (Castellini et al 2002a(Castellini et al , 2002bDal Bosco et al 2014a, 2014b and commercial information, the genotypes were sub-categorised with regard to their growth rate: slow (GR < 24 g/d; A, L, CL), medium (25 < GR 40 g/d; G, RM, K, NN) or fast-growing (GR > 41 g/d; R).…”