Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 1999
Publication Date: N/A
The objective was to estimate correlated responses of prepubertal uterine and ovarian traits to selection for either ovulation rate (OR) or uterine capacity (UC) in swine. Two replicates (A and B) were established for each OR, UC, and control (CO). OR at the estrus of conception was recorded on dams of the OR line. UC per uterine horn was measured as the number of fully-formed pigs born to dams of the UC line that were unilaterally hysterectomized-ovariectomized (UHO) prior to puberty. Boars and gilts from OR and UC dams with the highest records were selected for 11 generations in replicate A and 10 generations in replicate B. Then, intact replicate A gilts were mated within line to replicate B boars; correlated responses of litter size to selection for OR or UC were 2.0 or 1.5 pigs, respectively. UHO were performed at 164 d of age on random samples of 66 CO, 66 OR, and 65 UC gilts produced from crossing of replicates. The length of a uterine horn of each gilt was measured in situ (ISLGTH), excised (ELGTH), and hanging (HLGTH); CV ranged from 16 to 19%. Weights of the excised uterine horn (UWT) and ovary (OWT) were relatively more variable, with CV ranging from 28 to 36%. Gilts from selected and CO lines did not differ significantly for BW at surgery. Selection for OR increased (P < .01) ISLGTH (1.2 SD), ELGTH (1.1 SD), HLGTH (1.2 SD), and UWT (1.1 SD), but not OWT (.6 SD, P > .1). Effects of selection for UC on ISLGTH (.5 SD), ELGTH (.4 SD), HLGTH (.7 SD), UWT (.2 SD), and OWT (-.2 SD) were not detected (P > .05). This is the first swine selection experiment designed to evaluate conceptual interactions between OR and UC that affect fetal survival and litter size. Selection for increased OR at the estrus of conception in an annual production system enhanced prepubertal uterine development.