Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: June 10, 1996
Publication Date: N/A
Technical Abstract: The objective was to develop selection indexes of uterine and ovarian traits to increase uterine capacity of swine. Data were from two lines being selected for increased litter size (uterine capacity, UC) of unilaterally hysterectomized-ovariectomized gilts. Genetic and phenotypic parameters were estimated for UC, uterine length (UL), uterine weight (UW), ,and ovarian weight (OW) of 1,328 gilts with a multiple-trait animal model using DFREML procedures. Heritabilities were: .09, .50, .49, and .60 for UC, UL, UW, and OW, respectively. Phenotypic correlations were: UC-UL, .16; UC-UW, .06; UC-OW, .09; UL-UW, .75; UL-OW, .05; and UW-OW, .10. Genetic correlations were: UC-UL, .64; UC-UW, .53; UC-OW, .46; UL-UW, .80; UL-OW, .05; and UW-OW, .07. Selection indexes were calculated for all possible combinations of traits. Predicted change in UC from one standard deviation of selection based on UC was .17 pigs. Response in UC was 53, 27, and 22% higher with indirect single trait selection based on UL, UW, and OW, respectively. The best two trait index included UL and OW, had a heritability of .53, and gave a 91% increase in UC response over direct selection. The best three trait index included UL, OW and UC, had a heritability of .52, and gave a 103% increase in UC response, but these values differed only slightly from the corresponding values of .53 and 91% for the index of UL, UW, and OW and the two trait index of UL and OW. The latter two indexes could be calculated before puberty, allowing more animals to be measured and greater selection intensity. The index of all four traits had a heritability of .53 and a 103% increase in UC response. Predicted genetic change in UC would be greater using indirect selection based on UL, UW, and OW than by direct selection on UC.