Abstract
Although the Torbiscal line of Iberian pigs has been largely studied, some aspects of its history are not well known. In this paper, we used pedigree-based methods on a complete genealogy of 4,077 entries in order to get a comprehensive analysis of its four founder strains and to evaluate the expected genetic contribution of each ancestral strain to the successive generations of the composite Torbiscal line. Between-strain differences and specific heterotic effects on piglet weight at 50 days of age were estimated from records of 9,052 piglets born in 1,571 litters of a complete diallel cross among the four strains. Moreover, we assessed the genetic singularity of the current Torbiscal pigs by other three studies, based on whole genome SNP genotypes, focused on the measure of its genetic diversity and differentiation with respect to other domestic and wild pig populations. The STRUCTURE algorithm detected two uppermost levels of the whole population structure, corresponding to European and Asian ancestries. These results confirmed the exclusive European origin of the Torbiscal and other Iberian pigs and the admixed origin of the Duroc breed. Finally, the comparison of Torbiscal with a representative pool of Iberian pigs showed a maximum genetic differentiation in regions of chromosomes three and seven, including some genes related to the regulation of muscle development.
Highlights
From a publication on the seasonal influence on fecundity and litter performance in Iberian pigs (Dobao et al, 1983) until a recent study on the effects of breed, feeding status, and diet on adipogenic, lipogenic, and lipolytic gene expression in growing Iberian and Duroc pigs (Benitez et al, 2018), the research activity performed on the Torbiscal line has substantially contributed to increase the scientific knowledge of Iberian pigs
Miguel Odriozola, who was the founder of Torbiscal line, and devoted much of his brilliant career to the study of Iberian pigs, classified livestock populations in two classes according to their degree of artificialness
First degree populations of farm animals are those controlled by a large number of farmers, being genetically developed by adaptation to their particular environment and production system, without any standard racial or herd-book
Summary
From a publication on the seasonal influence on fecundity and litter performance in Iberian pigs (Dobao et al, 1983) until a recent study on the effects of breed, feeding status, and diet on adipogenic, lipogenic, and lipolytic gene expression in growing Iberian and Duroc pigs (Benitez et al, 2018), the research activity performed on the Torbiscal line has substantially contributed to increase the scientific knowledge of Iberian pigs. The composite origin of the Torbiscal line has been concisely described in some of the quoted papers, the relevance of this population justifies a more comprehensive genealogical and productive charac terization of its founder strains, its relatedness with these ones and its genetic singularity with respect to other pig populations, with the remain ing Iberian pigs. These are the objectives of the present study
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