Abstract
The aim of the present study was to assess whether or not a modified Whitten's medium lacking glucose and supplemented with 0.4% (w/v) bovine serum albumin (BSA) can sustain the viability of early-stage pig embryos during long-term culture followed by transfer to recipient gilts. Embryo collection was surgically carried out on Days 2, 3 or 4 (Day 0 = onset of estrus) by midventral incision. The 2-cell and 4-cell embryos recovered were placed in 100-μl droplets of Whitten's medium under mineral oil in an incubator gassed with 5% CO2 in air at 38.5 C. During culture, the embryos were morphologically evaluated every 24 h. Two-cell embryos from Day 2 donors developed to blastocysts and expanded blastocysts beyond the 4-cell block (11/11, 100%). Four-cell embryos from Day 3 and Day 4 donors also developed to blastocysts at high rates (85% [41/48] and 100% [34/34] respectively). When the embryos from Day 3 donors were surgically transferred to 3 recipient gilts following in vitro culture for 108 or 120 h in modified Whitten's medium, 1 recipient, which received 10 expanded and 5 hatching blastocysts, became pregnant and farrowed three piglets (3/15=20%). Similarly, when the embryos from Day 4 donors were transferred to 2 recipients after culture for 72 h, 1 recipient which received 17 expanded and 1 hatching blastocysts became pregnant and farrowed 8 piglets (8/18 = 44%).
