Detection and characterization of quantitative trait loci for growth and reproduction traits in pigs

A genome scan was performed on F-2 animals of a cross between Meishan and Dutch commercial pigs. Phenotypic data were available for growth traits and ultrasonic backfat thickness on 942-1151 animals, and for litter size on 249 and 206 animals at first and second parity, respectively. QTL analyses were performed using interval mapping by regression under the line-cross approach complemented by tests for genomic imprinting and sex-specific QTL effects. For backfat thickness, the analyses revealed significant QTL on chromosomes 2, 7, 14, and X, with significant imprinting for chromosomes 2 and 14. Significant QTL were detected for the different growth traits on chromosomes 1, 4, 7, and S. Both the QTL on chromosome 4 and chromosome 8 showed maternal expression for a specific growth stage. The QTL analyses for litter size revealed one suggestive QTL for first parity and three suggestive QTL for the second parity. Analyses under a half-sib model did not reveal additional significant QTL, but confirmed several of the QTL detected under the line-cross models. This study provides confirmation of several QTL affecting growth and fat deposition in pigs and adds interesting new insight into their mode of expression. Furthermore, additional significant and suggestive QTL were identified. (C) 2001 Elsevier Science B.V. All rights reserved.