Reproduction remains a significant limiting factor to the achievement of economic goals on dairy farms. Dairy producers are making increasing use of management aids, such as estrus detection devices and estrus or ovulation control programs, to mitigate the impact of poor heat detection. While such management aids are useful, their success is dependent on the rate that animals return to a predictable estrus cycle. The objectives were: 1) to determine the prevalence of anestrus in Ontario dairy herds,2) to evaluate herd and cow level risk factors for anestrus and 3) to investigate the impact of a progesterone releasing intravaginal device (PRID) on days to first service, first service conception risk and days from calving to conception in animals atrisk of anestrus.
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