Abstract

Oestradiol has been successfully used to synchronise oestrus and ovulation in anoestrous dairy cows first treated with progesterone for at least 5 days and then injected with oestradiol benzoate (ODB) during the following 24 to 48 h (Macmillan et al., 1994). The ovulatory effects are associ-ated with the ability of oestradiol to induce a surge of LH, especially during pro-oestrus. Although oestradiol has been injected in the period of pro-oestrus following an injection of prostaglandin F2α(PGF), this form of oestra-diol use has not been advocated even though the precision of synchrony is enhanced (Macmillan, K.L.; Burke, C.R.,1996).

KL, Macmillan, and VK Taufa

Proceedings of the New Zealand Society of Animal Production, Volume 57, , 238, 1997