Reproductive measurements in Sinclair and NIH miniature pigs: a retrospective analysis

The data presented here represent a retrospective analysis of information gathered while collecting data for other studies on miniature pigs. Two different breeds of miniature pigs, NIH and Sinclair, were used in this study. The NIH females were gilts, while Sinclair females included both gilts and sows. The pigs were checked twice a day for estrus and were mated at 12 and 24 h after the onset of estrus. One- and 2-cell stage embryos were collected on Day 2; while 4-cell, 8-cell, compact morula and blastocyst stage embryos were collected on Days 2.7, 3.5, 4.3 and 6.0, respectively. The percentage of recovery of these embryos was dependent upon the surgeon (P = 0.002) and the stage of development (P = 0.018). The number of ovulations was higher (P < 0.04) in the Sinclair sows (10.4 +/- 0.60) than in the Sinclair gilts (8.9 +/- 0.67) and in the NIH gilts (8.3 +/- 0.67). When the NIH gilts were divided into swine leukocyte antigen (SLA) haplotypes, it was found that SLA(dd) gilts (8.5 +/- 0.43) had more ovulations (P = 0.02) than SLA(ad) gilts (6.8 +/- 0.57). Some animals were treated with Regumate to synchronize estrus. The Sinclair gilts (7.8 +/- 0.28) and NIH gilts (7.7 +/- 0.27) took more days (P < 0.07) to show estrus than the Sinclair sows (6.3 +/- 0.58) after the removal of Regumate. Four of the animals had reproductive tract abnormalities; more specifically, a blind uterine horn or oviduct that was not patent with the other horn. All 4 were NIH gilts with the SLA(dd) haplotype.