Abstract
Simple SummaryBreed undefinition boosts the risk of irreversible breed loss due to its substitution by dominant breeds. Breed loss results detrimental for the fraction of the genetic pool which is linked to the value of livestock as perfectly adapted elements of domestic ecosystems among other desirable features. In turn, this ensures and maximizes population sustainability. The present study aimed to design a biometric characterization tool in autochthonous avian breeds and their varieties in Andalusia (south of Spain): Utrerana and Sureña breeds. For this, different quantitative and qualitative measurements were collected in 473 females and 135 roosters belonging to these breeds. Even though both genotypes belong to a common original trunk, discriminant canonical analysis (DCA) revealed clear differences between both breeds and within the varieties that they comprise. In particular, certain variables such as ocular ratio and phaneroptic characteristics, which may be intrinsically related to the capacity of the breeds to adapt to the environmental conditions in which they thrive, could allow breeders to develop breeding programs focused on the enhancement productive potential of individuals.This study aimed to develop a tool to perform the morphological characterization of Sureña and Utrerana breeds, two endangered autochthonous breeds ascribed to the Mediterranean trunk of Spanish autochthonous hens and their varieties (n = 608; 473 females and 135 males). Kruskal–Wallis H test reported sex dimorphism pieces of evidence (p < 0.05 at least). Multicollinearity analysis reported (variance inflation factor (VIF) >5 variables were discarded) white nails, ocular ratio, and back length (Wilks’ lambda values of 0.191, 0.357, and 0.429, respectively) to have the highest discriminant power in female morphological characterization. For males, ocular ratio and black/corneous and white beak colors (Wilks’ lambda values of 0.180, 0.210, and 0.349, respectively) displayed the greatest discriminant potential. The first two functions explained around 90% intergroup variability. A stepwise discriminant canonical analysis (DCA) was used to determine genotype clustering patterns. Interbreed and varieties proximity was evaluated through Mahalanobis distances. Despite the adaptability capacity to alternative production systems ascribed to both avian breeds, Sureña and Utrerana morphologically differ. Breed dimorphism may evidence differential adaptability mechanisms linked to their aptitude (dual purpose/egg production). The present tool may serve as a model for the first stages of breed protection to be applicable in other endangered avian breeds worldwide.
Highlights
In Spain, two hen trunks have historically been differentiated; the Atlantic trunk, generally comprising larger-format dual-purpose birds, with red earlobes and brownshelled eggs, and the Mediterranean trunk, consisting of lighter individuals, with white earlobes and of a white-shelled egg-laying morphotype [1]
The aforementioned features have been considered by breeders on a regular basis for breed ascription and animal classification. This segregation of the Atlantic and Mediterranean trunks would later be supported from a molecular perspective through the estimation of genetic distances using microsatellite markers [2]
Natural and human selection led to a high heterogeneity and variability of morphological characteristics in avian breeds [3,4]
Summary
In Spain, two hen trunks have historically been differentiated; the Atlantic trunk, generally comprising larger-format dual-purpose birds, with red earlobes and brownshelled eggs, and the Mediterranean trunk, consisting of lighter individuals, with white earlobes and of a white-shelled egg-laying morphotype [1]. The aforementioned features have been considered by breeders on a regular basis for breed ascription and animal classification This segregation of the Atlantic and Mediterranean trunks would later be supported from a molecular perspective through the estimation of genetic distances using microsatellite markers [2]. Natural and human selection led to a high heterogeneity and variability of morphological characteristics in avian breeds [3,4] Such high heterogeneity was promoted when breeding objectives (meat, eggs, or dual-purpose breeds) and, morphological characteristics started to differ and polarize among populations to adapt to environment requirements at the minimum biological cost. These differentiation processes determined breeds to base their adaptability strategies on their particular enhanced body features [5]
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