Efecto de la introducción de genética Duroc y de la restricción de vitamina A en la dieta sobre parámetros productivos, expresión génica y calidad de la carne en el cerdo ibérico

Abstract

The Iberian pig is a swine breed characterized by high fat deposition rate and limited capacity for lean tissue accretion. Its meat has a high fat content and a characteristic fatty acid profile, main factors determining the high quality of Iberian pig products. In order to improve productive performance and muscle development, this breed has been traditionally crossed with the Duroc breed. However, a decrease in intramuscular fat (IMF) and monounsaturated fatty acids (MUFA) content, parameters closely linked to meat quality, has been reported in those crossbred pigs. Previous studies showed than genetics and nutrition among others, are key factors controlling IMF content and composition. Hence, the main goal of this Thesis was to contribute to the knowledge on genetic and molecular mechanisms associated with target phenotypic traits in Iberian pig, specially the intramuscular fat content and composition, and to study the effect of a nutritional strategy, specifically dietary vitamin A restriction, on these mechanisms. Two different experiments were designed to achieve these objectives. In the first one, the effects of age and genotype on muscle transcriptome were studied in pure and Duroc-crossbred Iberian pigs at two developmental stages (birth and four months of age). Several phenotypic parameters and Longissimus dorsi (LD, at both ages) and Biceps femoris (BF, at birth) transcriptome were assessed. The second experiment allowed the study of vitamin A supplementation (10,000 IU/kg feed) and restriction (0 IU/kg feed) on target traits and gene expression. Experimental diets administration started at two (early restriction group) or four (late restriction group) months of age and their effects were studied through the growing and fattening phases ...