Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 1998
Publication Date: N/A
Interpretive Summary: One of the major determining factors in the price of market hogs today is backfat depth; thus, identification of regions of the genome affecting this trait could be very useful to the swine industry. With the development of a comprehensive genomic map for the pig genome, scans to detect economically important genomic regions can be initiated. Identification of regions controlling backfat was one of the objectives of the swine mapping program at MARC. We are reporting the detection of three genomic regions located on chromosomes 1, 7 and X affecting backfat identified with a genome wide scan in a reciprocal backcross population of Meishan and White composite pigs. The differences between the most extreme genotypes for each region was nearly 6 mm of average backfat. Evidence for other regions affecting backfat was also detected. The detected regions need to be tested in commercially relevant populations of swine to determine if they will be useful. These findings are quite significant and have advanced our understanding of the inheritance of quantitative characters. In addition, these results may advance our understanding of genetics of fat deposition and could be useful to scientists studying the genetics of obesity in humans. Further studies are necessary to determine what other traits are affected by the genes located in the identified regions and how they interact with other genes.
Technical Abstract: One of the major determining factors in the price of market hogs today is backfat depth. Therefore, identification of regions of the genome affecting this trait could be very useful to the swine industry. A large resource population (n=540) was developed by backcrossing F1 Meishan-White composite females to either Meishan or White composite boars. A genomic scan was conducted by genotyping all animals with microsatellite markers spaced at approximately 20 cM intervals across the entire porcine genome. Breed of origin for all chromosomal segments was determined using multipoint linkage procedures and a least-squares regression analysis conducted. Nominal p- values were converted to a genome wide level of significance to adjust for the numerous tests conducted. Traits analyzed were backfat depths at the first rib (FRIB), tenth rib (10th), last rib (LRIB), last lumbar (LLUM) vertebrae and an average of FRIB, LRIB and LLUM (AVBF) and weight of leaf fat (LEAF). Significant QTL were detected on chromosomes 1, 7 and X. Suggestive evidence for QTL was present on chromosomes 2, 5, 8, 9, 10, 13, 14, 15 and 17. Genotypic means for the loci detected indicated a predominantly additive mode of inheritance. The Meishan alleles produced fatter pigs for all loci except those on chromosomes 7, 10 & 15. Additional research needs to be conducted to refine the estimated position of each QTL and its effect and determine epistatic interactions. These loci need to be evaluated in other germplasms to determine if allelic variation at the QTL exists in other breeds.