Incidence of silent ovulation in dairy cows during post partum period
Isobe, N.; Yoshimura, T.; Yoshida, C.; Nakao, T.
Deutsche Tierärztliche Wochenschrift 111(1): 35-38
2004
ISSN/ISBN: 0341-6593 PMID: 14983753 Document Number: 583896
This study was undertaken to determine the incidence of silent ovulation in high-producing dairy cows, by monitoring ovarian cyclicity based on practical milk progesterone assay which was established in this study. The direct milk progesterone enzyme linked immunosorbent assay (ELISA) was developed using anti-progesterone-3(E)-carboxymethyloxime-BSA antibody as the antibody and horse radish peroxidase labelled progesterone as the tracer. High sensitivity (26 pg/ml, 0.65 pg/well), recovery rates (83-97%), reproducibility (CV of intra-assay 4.8-11.5%; CV of inter-assay 14.3-19.1%), and correlation between milk progesterone concentrations measured by the direct ELISA and the values obtained by the ELISA after extraction proved the reliability of the assay. In the second experiment, the incidence of silent ovulation was investigated based on the milk progesterone concentrations in 32 dairy cows within 70 days post partum. The incidences of silent ovulation at the 1st, 2nd, 3rd, and 4th ovulations postpartum were 83, 46, 13, and 0%, respectively. The most commonly observed patterns of sequential occurrence of silent ovulation in cows ovulating 2, 3, or 4 times within 70 days postpartum were silent-oestrus (50%), silent-silent-oestrus (60%), and silent-silent-oestrus-oestrus (67%), respectively. These results suggested that the present ELISA was a reliable and practically applicable method for determination of progesterone in milk. Moreover, high-producing dairy cows show a high incidence of silent ovulation at the first post partum ovulation as well as the second ovulation, which then decreases with the increasing frequency of ovulation.