Searchable, peer-reviewed, open-access proceedings from bioscience and biomedical conferences
Bioscientifica Proceedings (2019) 3 RDRRDR27 | DOI: 10.1530/biosciprocs.3.027

1CSIRO, Division of Animal Production, Private Mail Bag, Armidnle NSW 2350, Australia; 2NSW Agriculture, Agricultural and Research Advisory Station, PMB, Grafton, NSW 2460, Australia; 3Department of Agriculture, Pastoral and Veterinary Institute, Private Bag, Hamilton VIC 3300, Australia; 4Biotech Australia Pty Ltd. PO Box 20, East Roseville, NSW 2069, Australia; 5Prince Henry’s Institute of Medical Research, Clayton, VIC 3168, Australia; and 6Department of Physiology, University of New England, Armidale NSW 2351, Australia

Unlike in sheep, in which immunization against androstenedione causes mild and reasonably controlled increased ovulation rate, in similar studies cattle showed highly variable responses ranging from increased ovulation rate and fertility through to anovulation/anoestrus or superovulation. As a consequence, interest in manipulation of ovulation rate through this approach has declined and is now focused on immunological manipulation of endogenous inhibin following successful studies in sheep. Studies have concentrated on developing a prototype inhibin-based vaccine to be used for twinning in the Australian beef industry. The prototype vaccine (with recombinant ovine inhibin-α.3 fusion protein and Montanide:Marcol adjuvant) has proved to be very potent and control of the degree of ovarian stimulation has not been possible. The proportion of cattle with increased ovulation rate after inhibin immunization is affected by timing of booster vaccination within the ovarian cycle, time after vaccination, vaccine formulation and possibly genotype. Physiological studies show that cattle responding to the inhibin vaccine have increased plasma inhibin binding of native bovine inhibin, high plasma FSH concentrations, greater numbers of large (≥ 8 mm) follicles and fewer small (< 5 mm) follicles during the preovulatory wave of follicular development compared with control or non-responding animals. Significant correlations among the response parameters (i.e. inhibin binding, plasma FSH concentrations, number of large follicles and ovulation rate) have been demonstrated. The results indicate that greater understanding of the various processes of folliculogenesis will be necessary to achieve a controlled increase in ovulation rate in cattle.

© 1995 Journals of Reproduction and Fertility Ltd

Article tools

My recent searches

No recent searches.