Body conformation and slaughter traits in males and females of two three way experimental hybrids of free range chickens

Abstract

Univariate and multivariate character­ization of male and female chickens belonging to two three-way experimental hybrids developed for producing free range chickens, in comparison with Campero INTA as the reference genotype, both in terms of a set of linear measurements recorded before slaughter as well as with four zoometric indices, revealed an at least partially independent genetic basis for shape and body size. The principal component multivariate analy­sis of carcass yield at slaughter plus breast, leg-thigh and abdominal fat proportions evinced the presence of sources of variation for breast and leg-thigh independent of body fat content as well as two sources of variation for breast percent­age, one independent and the other negatively associated with leg-thigh proportion. Although the multivariate analysis allowed characterizing the birds of each sex in terms of some particu­larities of potential selective significance not ap­parent when using a univariate approach, dif­ferences among genetic groups within sex were not remarkable from a productive point of view. Slow-growing type birds evaluated in this study showed a good breast muscle development -un­like the old-fashioned field chickens- maintain the typical sexual dimorphism of the species and exhibit their characteristic “pheasant type” phe­notype together with a variable plumage pigmen­tation different from pure white which identifies and distinguishes them from those hybrids usu­ally exploited by the commercial poultry indus­try. Regarding slaughter traits both experimental three-way crosses can be considered similar not only between them but also when compare with the reference genetic group