Mapping Genes for Fatness and Growth on Pig Chromosome 13: A Search in the Region Close to the Pig PIT1 Gene
Previous research has shown that the PIT1 gene in several pig populations and the chromosomal region near PIT1 in some pig populations has been significantly associated with fatness and growth on pig chromosome 13. To confirm these previous results and to clarify the role of the PIT1 gene in controlling pig fatness and growth, this research project was focused on studying the chromosomal region close to the PIT1 gene. The ISU Chinese x U.S. pig families were used and the traits analyzed were birth weight, 21-day weight, 42-day weight, longissimus muscle area, backfat thickness at several locations, meat color, marbling and firmness on the carcass, and growth rate for selected time periods. The total number of F2 pigs used ranged from 241 to 330. Significant evidence of a genetic marker for first rib backfat thickness was detected approximately 20 centimorgans (cM) from the PIT1 gene. Evidence of a genetic marker for birth weight was detected at the estimated PIT1 position. These results confirmed the previous published research on pig chromosome 13 for the birth weight but suggest that other genes in the region may be partly responsible for the earlier results on the backfat thickness.