|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Technical Abstract: The goal was to identify chromosomal regions containing QTL that explain genetic variance of reproduction in pigs. A three-generation population was developed by crossing a control line (C) with a line selected for an index of ovulation rate and embryonic survival (I). Generation 10 differences between lines I and C were 6.7 ova, 3.3 fetuses, and -4.5% embryonic survival at 50 d of gestation and 3.1 fully formed pigs and 1.6 live pigs at birth. Phenotypic data on F2 females were analyzed for ovulation rate (n=428), age at puberty (n=295), litter size (n=362) and number of teats (n = 428). Litter size data included number of fully formed, live, stillborn, and mummified pigs. Grandparents, F1, and F2 animals were genotyped for 42 microsatellite markers distributed across chromosomes 1, 3, 4, 8, 13, and 15. Expected number of false-positive outcomes per genome-wide scan was calculated as presented by Lander and Kruglyak who recommended that a LOD score of 3 represents suggestive linkage with an expected number of false- positives of one per genome scan, and that a LOD score of 4.5 represents significant linkage with number of false-positives of 0.05 per genome scan. The LOD scores were calculated using least squares including effects of litter and replicate. Evidence for QTL influencing age at puberty was identified on chromosomes 1 (16 cM, LOD = 3.92 and 129 cM, LOD=3.12) and 8 (120 cM, LOD = 3.74) using the USDA-MARC linkage map. Evidence suggested a QTL for number of stillborns on chromosome 13 (104cM, LOD = 4.04). More markers are needed to better estimate locations and effects of these putative QTL. Because age at puberty is an economically important trait which is labor intensive to measure, selection for age at puberty using markers linked to QTL may be useful to the pig industry.