Predicting Optimal Time of Insemination in Cows that Show Visual Signs of Estrus by Estimating Onset of Estrus with Pedometers

¹ Institute for Animal Science and Health, PO Box 65, 8200 AB Lelystad, The Netherlands
² Animal Health Service, PO Box 9, 7400 AA Deventer, The Netherlands

An experiment was designed to estimate the optimal interval from the beginning of estrus to artificial insemination (AI). The data were analyzed by means of a mathematical model. The analysis was based on pedometer readings and results of rectal palpation at 42 to 49 d post-AI of 171 breedings in 121 cows. The chance of conception was highest between 6 and 17 h after increased pedometer activity; the estimated optimum was at 11.8 h. In this data file, the effects of disease, inseminator, time of AI (a.m. or p.m.), and bull did not contribute to the improvement of the model. The effects of disease were not significant because of the low incidence of any specific disease. Activity measurements can be used as a tool for AI strategy to improve conception in groups of healthy cows and heifers already showing visual signs of estrus.

Key Words: estrus • timing of insemination • pedometers

Submitted on June 18, 1996
Accepted on October 15, 1996