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Proximity sensors attached to ewes and rams at mating can predict date of lambing

Paul Shorten , Jacqueline Peers-Adams, Patricia Johnson, Cheryl O'Connor, Jenny Juengel

Abstract

Context. Determining the birth date of lambs is important as it is used in analysis for the generation of breeding values for lamb liveweight and lamb growth traits. Aims. We used proximity sensors to measure the daily interactions between 300 ewes and 3 rams over the mating period for 2 successive trial years to test the hypothesis that lambing date can be predicted for a typical New Zealand commercial mating system. Methods. The day that the ewe had the highest number interactions with the 3 rams was used to estimate the day of conception. Key Results. In both trial years 89% of ewes had a proximity sensor-based predicted lambing date ± 6 days of the measured lambing date. In the two trial years 81% and 78% of ewes had a predicted lambing date ± 3 days of the measured lambing date. This demonstrates that the performance of the proximity sensor-based method to predict lambing date was consistent between years. Conclusions. Proximity sensors therefore provide an indirect method to study mating behaviour that can be used to predict the birth date of lambs. Implications. This tool can be used by breeders to improve the breeding values of sires for lamb growth and liveweight when lambs are not tagged at birth and the management of ewes by grouping them together by gestational age.

AN24331  Accepted 10 January 2025

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