End of Project ReportReproductive efficiency is a major factor affecting production and
economic efficiency of beef herds. For herds using artificial insemination
(AI) heat detection rate and calving rate are the two major determinants
of compactness of calving and ultimately the calving-to-calving interval.
Heat detection is a time consuming repetitive chore that must be carried
out up to 5-times each day for as long as AI is used. Heat detection rate,
usually measured as submission rate, is hugely variable from herd-toherd
but for most herds only between 40% and 70% of cows that exhibit
heat are actually detected by the stockman. Despite an increased
understanding of the endocrine control of the oestrous cycle the goal of
fixed-time insemination is not yet consistently achievable in either cows
or heifers treated at different stages of the oestrous cycle and in different
physiological states. The overall objective of the this project was to
develop an improved cost effective hormonal method to control the time
of ovulation to allow beef cows be bred by AI without the need for heat
detection. A total of 3 studies were carried out and the results are
summarised in this report.Department of Agriculture, Food and the Marin
