Egg Transfer in the Cow: Pregnancy Rate and Egg Survival

Abstract

data are available on pregnancy rates following the surgical transfer of fertilized cow eggs. Rowson et al. (1969) recorded a pregnancy rate of 91 % in a group of eleven heifers, each of which received either two or three fertilized eggs transferred to the uterine horn adjacent to the ovary carrying the corpus luteum. No incidence of twinning was recorded following these transfers. Rowson et al. (1971) reported a twinning rate of 50% following the transfer of one fertilized egg to each uterine horn in eighteen recipients. The total egg survival in this study was 61\m=.\1 %. When both the donor and recipient were in oestrus on the same day, however, the corresponding rates were 71\m=.\4% and 78\m=.\6%. The necessity for close synchronization to achieve high pregnancy rates was again shown by Rowson et al. (1972) when they reported a pregnancy rate of 91\m=.\1% following transfers where the donor and recipient came into oestrus on the same day. This pregnancy rate fell to just over 50% when the donors and recipients were out of phase by 1 day. Studies are in progress to determine some of the factors which affect the outcome following the surgical recovery of fertilized eggs from donor animals after superovulation and the transfer, both surgical and non-surgical, of one fertilized egg to each uterine horn in recipient animals. This communication deals with pregnancy rate and egg-survival, following surgical transfers in heifers.

Comparison of the fetal survival rate in heifers after the transfer of an embryo surgically to one uterine horn and non-surgically to the other

“…The pregnancy rate after a surgical transfer to the horn ipsilateral to the corpus luteum (Group 1 ) was similar to that reported by others (Rowson et al, 1969;Sreenan & Beehan, 1974). The non-surgical transfer of an embryo to the contralateral uterine horn did not therefore impair the pregnancy rate obtained with the surgically transferred embryos.…”

“…By contrast the fetal survival rate after surgical transfer has been high (Rowson, Moor & Lawson, 1969;Sreenan & Beehan, 1974). A within-animal com¬ parison of the two methods was therefore undertaken to elucidate the factors involved.…”

Embryo Transfer in Cattle

“…Work in Ireland, which reported high pregnancy rates after surgical transfer, also observed a greater proportion of pregnancies among the exactly synchronized cattle than in those out-of-phase by ±1 day (Sreenan and Beehan, 1974;Sreenan eta/., 1975). Although there had been a suggestion by Trounson et al (1976) that cattle out-of-phase by ±1 day might show higher pregnancy rates when the donor was in advance of the recipient, more extensive Canadian data did not support this , showing a 63% pregnancy rate in 1126 cattle at exact alignment, 60% in 334 recipients which had shown oestrus 1 day ahead of donors (-1 ) and 49% in 556 cattle exhibiting heat 1 day after their respective donors (+1).…”

“…It was later reported, however, that bovine follicular fluid would support limited cleavage of cattle eggs (Thibault, 1966;Sreenan, 1968) and shortly afterwards successfully employed Tissue Culture Medium (TCM) 199 as a recovery and transfer medium. Although TCM 199 was used in the early and mid-1970s by the Cambridge group, as well as by Betteridge and Mitchell (1974), Sreenan and Beehan (1974), Sreenan et a/. (1975) and many others, it was by no means regarded as an ideal medium.…”

Relationship between Plasma Progesterone Concentration and Number of Conceptuses and Their Growth in Superovulated Cattle

“…Elevated circulating P 4 levels in the immediate post-ovulation period advance the temporal changes in the uterine environment by altering endometrial gene expression [14,27]. Temporal synchrony between the embryo and uterus is critical for optimal conceptus survival in cattle [36,37] and sheep [38,39]. Therefore, excessively high plasma P 4 concentrations and large numbers of conceptuses might disturb the pattern of change in endometrial gene expression and result in asynchrony between the environment of the uterine endometrium and the developmental stage of the conceptuses.…”