Trans-vaginal oocyte retrieval and subsequent in vitro production of embryos from a cow involuntarily culled : case report

A Holstein cow of high genetic merit, in late lactation (205 days) and diagnosed with salpingitis (after 4 infertile services and veterinary consultation), was subjected to 1 trans-vaginal oocyte collection attempt, prior to slaughter.Of an estimated 10 follicles punctured, a total of 4 cumulus-oocyte complexes were retrieved. These were matured in vitro in a maturation medium for 24 hours. After 24 hours maturation, the oocytes were fertilised in vitro with Percoll-processed frozen / thawed imported semen, of the owner's choice. Fertilisation was achieved in a modified Tyrode's medium. At 18 hours post-insemination, the presumptive zygotes were transferred into culture in vitro in Charles Rosenkran's aminoacid medium and supplemented on Day 4 post-insemination with 10 % foetal calf serum. All in vitro procedures were conducted in 50 m medium droplets, under oil, in a humidified incubator at 38.5 oC in 5% CO2 in air. Three of the potential zygotes cleaved and, by Day 7 of culture, these had developed to the morula stage. The embryos were frozen in 1.5 M ethylene glycol and later transferred non-surgically to synchronised Holstein recipient heifers. One morula resulted in the only pregnancy and subsequent birth of a healthy heifer calf. An independent commercial company confirmed parentage through standard bloodtyping assays. The genetic salvage of oocytes, for in vitro production of embryos, has potential benefits to the producer.