Bisection of bovine morulae and blastocysts from superovulated Danish dairy cows.
Sixtyfour compacted morulae and blastocysts were bisected with a microscalpel. The majority of the demi-embryos (n = 122) were reinserted into separate zona pellucidae (ZP) before non-surgical transfer to 113 synchronized recipients, as singles (n = 98) (DE-S) or in pairs (n = 30) (DE-P). Thirty non-manipulated embryos (E) were transferred during the same period and served as controls. Pregnancies were diagnosed by rectal palpation 4-7 weeks after transfer. The pregnancy rates for DE-S, DE-P and E were 32%, 53% and 40%, respectively (P greater than 0.05). A substantial number of abortions were recorded between 50 and 250 days of pregnancy among the recipients with DE-S. The fetal survival rate for DE-S was reduced to 21% and significantly lower (p less than 0.05) than the survival rates of DE-P (43%) and E (40%). The quality of DE and the presence of ZP did not significantly influence the results. No conclusive reasons for the fetal loss could be found but different possibilities are discussed.
Holm
P
P
Department of Research in Cattle and Sheep, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
Greve
T
T
Bak
A
A
Schmidt
M
M
D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D002417:Cattle / Q000196:embryology*; D005260:Female; D005298:Fertility; D009028:Morula / Q000502:physiology*; D011247:Pregnancy; D014427:Twins