Origin, Selection and Current Status of the Utrerana Chicken Breed: A Review.

The conservation of threatened local livestock genetic resources involves characterising them to implement conservation strategies. The Utrerana is a Mediterranean-type chicken breed, included in the Official Catalogue of Livestock Breeds of Spain and in the Domestic Animal Diversity Information System (DAD-IS) of the Food and Agriculture Organization (FAO), native to south Spain created in 1926 by a farmer from Utrera (Seville province). It was selected for laying performance and with four plumage varieties (White, Black, Black-barred and Partridge), reaching average yields of 180 eggs per hen per year. It was widely used in commercial farming in the second quarter of the 20th century, being subsequently displaced in the second half of the 20th century by the spreading of the improved foreign breeds and lines. The Utrerana breed was reared from then on for its aesthetic values and in backyard systems, being endangered with a vulnerable local risk status (1822 birds in 2022 with an increasing trend) and having worsened its laying performance as selection for productivity ceased. The breed has received little attention from the research community. Therefore, this work aims to review the literature on the origin, selection, genetic and productive characterisation and status of the populations of the breed, as well as the conservation strategies. The Utrerana chicken is a polymorphic breed showing high genetic diversity, sexual dimorphism and morpho-functional differences among varieties. Currently, Utrerana hens start laying at 6 months of age, and a hen lays 94-121 high quality eggs (59-64 g) per year, showing seasonality. It is a slow-growing breed with mature weights of 2.4-2.6 kg for roosters and 1.9-2.0 g for hens. The Utrerana chicken breed is rustic and adapted to alternative farming systems. This review has identified research gaps to be filled, such as characterising the carcass and meat quality of the Utrerana chicken, and evidences the need to make efforts to promote the breed and expand its populations.