Embryonic loss in sows with repeated propensity for small litter size.

Information is lacking as to the timing and cause of sows that repeatedly have low litter size over several parities. Sows evaluated for the present study had at least two parities either small <or=7 (SL) or normal >or=12 (NL) litter size. Following breeding of sows with contemporary boars, reproductive tracts were obtained on day 30 of gestation. There was no difference (p > 0.10) between SL and NL sows in the number of CL, embryo weight or placental length. The total number of embryos and embryonic survival tended to be lower (p < 0.10) in SL sows compared with NL sows, but there were 5.1 less viable embryos (p < 0.03) in SL. Results indicate that time of conceptus loss in SL sows was variable throughout gestation.