In-vitro production of cattle embryos: problems with pregnancies and parturition.
Using complex media containing serum and somatic cells, pregnancy rates following transfer of single, day 7 advanced-stage blastocysts approached 60%, while pregnancy rates of morulae or day 8 blastocysts were substantially lower. Pregnancies resulting from in-vitro-derived embryos were characterized by the following features: sex ratio skewed in favour of males; increased spontaneous abortion rate throughout gestation; reduced intensity of labour in recipients; and increases in birth weights, dystocias, calf mortality, and fetal abnormalities. In an attempt to improve the normality of pregnancies, a field trial was conducted within the commercial in-vitro programme at Em Tran. Following fertilization in vitro, equal numbers of zygotes were put into a Ménézo's B2-buffalo rat liver cell (B2-BRL) coculture system with (S+) or without (S-) 10% serum for the first 72 h of in-vitro culture. On day 4, all embryos were moved to fresh medium and cultured to day 7 in B2-BRL with serum. The efficiency of blastocyst production from oocytes (19.6 versus 17.8%) and the pregnancy rate at 60 days (47.8 versus 47.1%) did not differ between S+ and S-. Likewise, there was no difference between S+ and S- in the percentage of male calves (53.9 versus 54.3%), abortions (13.1 versus 11.9%), percentage of live calves (78.8 versus 81.4%), or congenital abnormalities (4.3 versus 3.3%).
Hasler
J F
JF
Em Tran, Inc., Elizabethtown, PA 17022, USA. jfhasler@redrose.net
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods*; D008297:Male; D007744:Obstetric Labor Complications / Q000662:veterinary*; D018587:Oocyte Donation; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000662:veterinary*; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011270:Pregnancy, Animal; D012189:Retrospective Studies; D012744:Sex Ratio
D003470:Culture Media