Role of male novelty and familiarity in male-induced LH secretion in female sheep
T. Jorre de St Jorre A B , P. A. R. Hawken A B and G. B. Martin A B C
+ Author Affiliations
- Author Affiliations
A School of Animal Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
B UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
C Corresponding author. Email: graeme.martin@uwa.edu.au
Reproduction, Fertility and Development 24(4) 523-530 https://doi.org/10.1071/RD11085
Submitted: 7 April 2011 Accepted: 25 July 2011 Published: 16 November 2011
Abstract
Ewes supposedly need to be separated from rams before male stimuli can increase gonadotrophin secretion and induce ovulation. In the present study, we investigated the LH response of ewes to ‘novel’ and ‘familiar’ rams after varying periods of separation. In Experiment 1, ewes (n = 8 per treatment) were separated from familiar rams for 15 min or 1 month and then exposed to either familiar rams, novel rams or novel wethers. After 15 min or 1 month of separation, exposure to novel rams increased pulsatile LH secretion (P < 0.05) and induced an LH surge in all ewes whereas exposure to familiar rams or novel wethers had no effect on LH secretion (P > 0.1). After 1 month of separation, re-exposure to the same familiar rams increased pulsatile LH secretion (P < 0.05) in six of eight ewes, but only induced an LH surge in two of eight ewes. In Experiment 2, familiar rams were removed and returned after 15 min, 1 day or 17 days (n = 5 per treatment). None of these treatments affected LH secretion. We conclude that separation of ewes from rams is a prerequisite for familiar rams to increase LH secretion, but is not necessary if the rams are novel.
Additional keywords: luteinising hormone, male effect, ram effect.
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