Progesterone and estradiol-17beta in the peripheral plasma of Brahman cows with single and twin pregnancies.
Peripheral plasma samples from Brahman cows with single and twin pregnancies were assayed for progesterone and estradiol-17beta throughout pregnancy. The twin pregnancies were obtained by transfer of Friesian embryos to inseminated single-ovulating Brahman cows. The twin-bearing cows had significantly higher levels of progesterone at 8 and 36 weeks of pregnancy. There were no differences in estradiol-17beta levels until the pre-parturient rise which occurred earlier in twin pregnancies. Intra-muscular injection of progesterone had no measurable effect on peripheral plasma levels of estradiol-17beta in Charolais cows 31 - 32 weeks pregnant.
Shelton
J N
JN
Department of Immunology John Curtin School of Medical Research Australian National University Canberra, Australia 2601.
Summers
P M
PM