The influence of culture and transport on pretransfer development and posttransfer survival of sheep embryos

Sheep embryos were collected under sterile conditions in Dulbecco's Phosphate Buffered Saline (DPBS) + 10% Fetal Calf Serum (FCS) and cultured in DPBS + 20% FCS at 37 degrees C. They were classified according to their stage of development, from the lowest stage, 13 (less than a morula) to the highest stage, 20 (hatched blastocyst). Morphology was graded from 1 for excellent to 5 for degenerated. All embryos placed in the experiment had a development stage classification of 14 (morula) or higher and morphology classification of 1 to 3. Thirty-four embryos cultured in the laboratory for 24 h (Treatment B) and 32 embryos handled the same way except that they were transported for approximately 12 h (Treatment C) increased an average of 1.8 development classification scores and decreased -0.84 and -0.58 morphology classification scores for the two treatments, respectively. Twelve embryos in Treatment D (the same as Treatment C except that they were cultured in the laboratory for an additional 24 h) progressed 2.2 development classification scores during 48 h culture and did not change (-0.08) in the morphology classification score. The development estimates related to length of culture time but showed no affect of transport. Seventy-five percent of 20 embryos transferred in Treatment C and 42% of 12 embryos in Treatment D survived to parturition, demonstrating that the procedures used to transport and culture them for 24 and 48 h, respectively, maintained embryos capable of post transfer survival. Forty-one percent of the 22 embryos transferred in Treatment A (noncultured) and 20% of 20 embryos in Treatment B survived.