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United States Department of Agriculture

Agricultural Research Service

Title: Prenatal Mortality Throughout Gestation in Lines of Pigs Selected for Either Ovulation Rate Or Uterine Capacity

Authors
item Freking, Bradley
item Leymaster, Kreg
item Christenson, Ronald
item Vallet, Jeffrey

Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: October 26, 2004
Publication Date: September 1, 2005
Citation: Freking, B.A., Leymaster, K.A., Christenson, R., Vallet, J.L. 2005. Prenatal mortality throughout gestation in lines of pigs selected for either ovulation rate or uterine capacity [abstract]. Midwestern Section of the American Society of Animal Science. 83(Suppl. 2):41. Paper No. 28.

Technical Abstract: Selection for 11 generations for either ovulation rate (OR) or uterine capacity (UC) resulted in 19.6% greater prenatal survival at term in UC compared to OR. Our objective was to characterize prenatal mortality throughout gestation in each line, including the unselected control line (CO). A sample of 50 gilts from each line for each of three farrowing seasons was subjected to unilateral-hysterectomy-ovariectomy surgery at approximately 160 d of age and mated within line at approximately 280-d age. Gilts were assigned within sire to be harvested at d 25, 45, 65, 85, or 105 of gestation. Ovulation rate and number of live fetuses were recorded for each pregnant gilt (n = 298). A mixed model analysis of variance was conducted. Fixed effects of farrowing group, line, gestation age, and two-way interactions were fitted. The random effect of sire (n = 88) of the gilt within farrowing group and line was used to test line differences. Ovulation rate of OR line gilts (18.3 ± 0.3) exceeded (P < 0.001) both the CO and UC line, 15.3 ± 0.3 and 14.1 ± 0.3, respectively. Line by gestation age interacted to affect number of live fetuses (P < 0.001). Least squares means for CO line were 10.7, 8.3, 7.9, 7.0, and 7.2 live fetuses for d 25, d 45, d 65, d 85, and d 105, respectively (average SE = 0.52). Corresponding means from the OR line were 13.6, 8.5, 8.1, 6.4, and 6.5 live fetuses, respectively (average SE = 0.49). UC line means were 10.3, 9.3, 8.4, 7.8, and 7.9 live fetuses, respectively (average SE = 0.53). In each line the number of live fetuses at d 25 was about 72% of ovulation rate. Mortality was highest in the OR line, intermediate in the CO, and lowest in the UC line to d 45. Losses continued to occur from d 45 to d 105 but line differences in number of fetuses at d 45 were maintained to d 105. Selection for uterine capacity has improved fetal survival during the critical time period between d 25 and d 45.

Last Modified: 9/22/2014