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The Nature of Reproductive Failures in Repeat-Breeder Sows¹

University of Wisconsin

Abstract

Data are presented on 63 females that had been bred at a to 4 different heat periods without conceiving. Repeat breeding was due to a failure of fertilization in 53.4 percent of the gilts and 32.6 percent of the sows. Accountable failure of fertilization due to bilateral tubal abnormalities, bilateral missing segments, or bilateral cystic follicles comprised 50.0 percent of the gilts and 15.8 percent of the sows. Unaccountable failure of fertilization (no gross barriers present) made up 3.4 percent of the gilts and 16.8 percent of the sows. Embryonic death was responsible for repeat breeding in 23.9 percent of the gilts and 67.4 percent of the sows. Thus, the major cause of repeat breeding in gilts appeared to be a failure of fertilization due to genital abnormalities, while in sows it was primarily because of embryonic death. Animals with normal embryos 25 days after one additional breeding included 22.7 percent of the gilts and none of the sows.

¹ Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. From the Departments of Animal Husbandry and Genetics, Paper No. 397 from the Department of Genetics.