Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2000
Publication Date: December 20, 2000
Citation: Christenson, R.K., Leymaster, K.A. 2000. Effects of selection for ovulation rate or uterine capacity on gravid uterine, farrowing, and weanining traits in swine [abstract]. Journal of Animal Science. 78 (Supplement 1):202. (Abstract #853) Technical Abstract: Eleven generations of selection for ovulation rate (OR) or uterine capacity (UC) increased (P < 0.01) OR (3.2 ova) or UC (1.1 pigs per uterine horn) in swine [Leymaster & Christenson, J. Anim. Sci. 78(Suppl. 1), 2000]. Our objective was to explore the effects of enhanced OR or UC on gravid uterine, farrowing, and weaning traits. Littermate control- (CO), OR-, or UC-line gilts were randomly assigned either to be unilaterally hysterectomized-ovariectomized, mated within line, and slaughtered at 105 days of gestation or to remain intact, mated within line, and farrowed. At slaughter, CO line (n = 80) means for gravid uterine horn, total fetal, total placental, and empty uterine weight were 10.6 +/- 0.4, 5.4 +/- 0.2, 1.31 +/- 0.05, and 1.87 +/- 0.05 kg, respectively. Gilts selected for OR (n = 78) or UC (n = 62) deviated from the CO gilts by -0.9 and 1.5**, -0.5 and 0.8**, -0.21** and 0.16**, and 0.04 and 0.15* kg, respectively (*P < 0.05, **P < 0.01). UC exceeded CO line gilts by 8 to 15% for these reproductive traits. At farrowing, CO line (n = 84) means for total number of pigs born, litter birth weight, number of pigs weaned, and litter weaning weight were 10.6 +/- 0.3 pigs, 13.6 +/- 0.3 kg, 8.9 +/- 0.3 pigs, and 40 +/- 1.3 kg, respectively. Gilts selected for OR (n = 66) or UC (n = 62) deviated from the CO gilts by 0.7 and 0.9* pigs, -0.3 and 0.8* kg, 0.1 and 0.3 pigs, and 0 and 1 kg, respectively (*P < 0.05). OR and UC line gilts produced 7 and 9% more pigs at birth than CO line gilts. Simultaneous increases in both OR and UC are necessary to produce substantial increases in litter size at birth and subsequent farrowing and weaning traits.