Selection for uterine capacity improves lifetime productivity of sows

Authors: Freking, Bradley - Brad; Lents, Clay; Vallet, Jeff

Submitted to: Animal Reproduction Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2016
Publication Date: 4/1/2016
Publication URL: http://handle.nal.usda.gov/10113/62078
Citation: Freking, B.A., Lents, C.A., Vallet, J.L. 2016. Selection for uterine capacity improves lifetime productivity of sows. Animal Reproduction Science. 167:16-21.

Interpretive Summary: Economic potential of the swine industry as well as animal wellbeing could be enhanced by improving uterine capacity, a component trait of litter size. Increased lifetime productivity of sows would be realized through improved prenatal survival. Selection in gilts for uterine capacity was conducted for 11 generations and the improved fetal survival resulted in increased number born alive with a similar average birth weight indicative of better developed piglets. It was our objective to establish the impact of direct selection for uterine capacity compared to a control line when gilts were able to express reproductive performance during later parities under a continuous flow farrowing system. These results indicated advantages of the uterine capacity line in improved fetal survival and reduced numbers of stillborn piglets, which resulted in increased number born alive with a similar average birth weight and increased total weaning weight from sows through four parities. The small differences between lines for numbers born and number weaned at each parity, combined with improved retention of sows in later parities resulted in significantly increased total weaning weight per sow through four parities for the uterine capacity line. Results of this study indicate that genetic and management strategies implemented that improve uterine capacity in gilts expected to be maintained as breeding replacements would reduce culling of sows and increase productivity during later parities of a sow’s reproductive lifetime. Results are also suggestive that selection for uterine capacity has the potential to improve piglet quality and health.

Technical Abstract: Selection for 11 generations for uterine capacity (UC) increased litter size in gilts by 1.6 more fully formed pigs at birth compared to an unselected control line (CO) despite averaging 1 less ova shed. Our objective was to quantify line-by-parity interactions and characterize litter performance traits of sows in each line at later parities. Gilts farrowed in contemporary groups of 19 litters and were maintained through four parities if successfully mated in that contemporary group. A total of 243 litters and 2,639 piglets were analyzed. Fixed effects of farrowing group, line, parity (1 to 4), and two-way interactions involving line were fitted. Sire (n = 57) of the sow within farrowing group and line was fitted as a random effect. No significant line-by-parity interactions were observed. Parity effects were detected (P < 0.01) for individual piglet birth weight, pre-weaning gain, and weaning weight. Parity effects were also detected (P < 0.05) for total number born, average and total litter birth weight, and average and total litter weaning weight. Selection line differences for litter traits were detected (P < 0.05) for number stillborn piglets and approached significance (P = 0.06) for number weaned. Retention in the herd was greater (P < 0.05) with an average of 2.33 parities for the UC line females compared to 1.87 parities for the CO line. This resulted in favorable cumulative lifetime productivity of the UC line for total number born, number born alive, litter birth weight, number weaned, and litter weaning weight.