The Assessment of a Multifactorial Score for the Adaptability Evaluation of Six Poultry Genotypes to the Organic System

SIMPLE SUMMARY: The choice of a suitable poultry genotype for the organic system is still an open question. Currently, poultry genotypes are mainly classified on the basis of their daily weight gain (DWG). However, it is important to underline that the organic system is characterized by the presence of outdoor space; therefore, the grazing capacity of chicken and other intrinsic characteristics are crucial aspects. Indeed, although DWG is an important parameter, it is probably not the only factor that should be considered to determine the adaptability of poultry to this system, in which the genotype could also have an important role. Accordingly, this study defines an adaptability score (AS) using a multifactorial approach in order to consider simultaneously different variables such as behaviors, plumage conditions, and body lesions. Moreover, the specific effect of DWG and genotype on the AS were evaluated. This allowed us to conclude that the DWG and genotype are connected, but the chicken genotype is the driving force that should be considered in order to evaluate poultry’s adaptability to organic systems. ABSTRACT: This study aimed to develop an adaptability score (AS) for chicken strains, which includes behavioral, plumage conditions, and body lesion indicators through a multifactorial approach. A total of 600 male chickens from 6 poultry genotypes—Ranger Classic (R1), Ranger Gold (R2), Rowan Ranger (R3), Hubbard Red JA (A), CY Gen 5 × JA87 (CY), and M22 × JA87 (M)—were reared under organic conditions, fed ad libitum, and individually weighed weekly to calculate the daily weight gain (DWG). The behavioral observations consisted of the explorative attitude (EA), recorded at 21 days, and the behavioral patterns (BPs) recorded the week before the slaughter. The AS was established by a principal component analysis, and the AS of these genotypes was compared. Moreover, the effect of DWG and genotype on the AS was evaluated by univariable and multivariable regression models. Although the DWG and genotype were strictly dependent, genotype was the most important factor affecting the AS. In fact, its effect was significant both in univariable (p < 0.001) and multivariable models (p < 0.001). Conversely, the DWG was significant only in the univariable and lost significance when the effect of genotype was introduced in the model.