Exposure to androgenised steers did not improve the fertility obtained in progesterone-based fixed-timed artificial insemination programs in extensively managed cows and heifers
R. UngerfeldDepartamento de Fisiología, Facultad de Veterinaria, Lasplaces 1550, Montevideo 11600, Uruguay. Email: rungerfeld@gmail.com
Animal Production Science 50(1) 68-71 https://doi.org/10.1071/AN09036
Submitted: 3 March 2009 Accepted: 22 September 2009 Published: 17 December 2009
Abstract
Biostimulation – the stimulation of females’ reproductive activity by the presence of males – has been used to stimulate postpartum rebreeding in cows, and to advance puberty in heifers. The objective of the present experiment was to determine whether previous exposure to androgenised steers improves conception rates after a progesterone-based fixed-timed artificial insemination program applied during spring. Three trials were carried out between October and January (spring–early summer) with a total of 903 Hereford and Hereford × Angus cows and heifers. All of the females were isolated from male contact (minimum distance = 4000 m) 3 months before the beginning of the experiments. While one group (EXP) in each trial was exposed to androgenised steers for 20 days, the other group (ISO) remained isolated from males (bulls, steers) during the experiment. In trial 1, 248 and 267 heifers were included in the EXP and ISO groups, respectively; in trial 2, 141 and 134 spring calving cows were used for the same treatments; and in trial 3, 53 and 60 autumn-calving cows were respectively included in the experimental groups. All animals were joined and a traditional progesterone-based fixed-timed artificial insemination program was applied to all of them. Pregnancy was determined 45–50 days after insemination with transrectal ultrasound. There were no differences between the EXP and ISO groups in any of the trials. The general conception rate was 54.6, 50.2 and 54.0% in trials 1, 2 and 3, respectively. Overall, it was concluded that exposition to androgenised steers does not improve the fertility obtained in progesterone-based fixed-timed artificial insemination programs in extensively managed cows and heifers.
Additional keywords: male effect, pheromones, socio-sexual stimulus.
Acknowledgements
I acknowledge Dr Sergio Kmaid, Dr Silvana González, and Ingeniero Agrónomo Alejandro Urchipía, for the field work. Financial support: Turcel (Soriano, Uruguay), Fundaciba (Montevideo, Uruguay).
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