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Temporal variation in LH and testosterone responses of rams after the introduction of oestrous females during the breeding season

Temporal variation in LH and testosterone responses of rams after the introduction of oestrous... Summary. The response of sexually experienced Ile-de-France rams to the presentation of oestrous females in October at sunrise (Subgroup S) or at 11:00 h (Subgroup N) was studied and compared with unstimulated controls (Subgroup C). Animals (12 per group) were bled for 7 h at 20-min intervals, starting 3 h before stimulation by oestrous females (3 per group). Eight rams from Subgroup S showed an increase of LH pulse frequency and only 3 in Subgroup N (P < 0·03). In Subgroup S the introduction of females led to 2- and 3-fold increases in LH pulse frequency during the stimulation period compared with values in Subgroup C or before the stimulation period (3, 1·6 and 1 peaks/rams/6 h respectively; P < 0·05). The presence of females also led to an increase in mean testosterone concentrations, and small increases in basal and mean LH values. No differences were found in LH peak amplitudes. In Subgroup N only inconsistent evidence of increases in mean LH and testosterone values was found. No differences between Subgroups S and N in behavioural patterns during stimulation were detected. We conclude that the presence of females affects LH pulse frequency at sunrise but not at noon during the breeding season and this effect is at least partly independent of sexual behaviour. These results suggest a possible circadian variation in CNS sensitivity involving the hypothalamic regulation of LH secretion in response to the presence of oestrous females.Keywords: temporal variations; LH; testosterone; ram; female effect; teasing http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Reproduction Bioscientifica

Temporal variation in LH and testosterone responses of rams after the introduction of oestrous females during the breeding season

Reproduction , Volume 83 (1) – May 1, 1988

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References (37)

Publisher
Bioscientifica
Copyright
Copyright © 1988 The Authors. All Rights Reserved.
ISSN
1470-1626
eISSN
1741-7899
DOI
10.1530/jrf.0.0830201
Publisher site
See Article on Publisher Site

Abstract

Summary. The response of sexually experienced Ile-de-France rams to the presentation of oestrous females in October at sunrise (Subgroup S) or at 11:00 h (Subgroup N) was studied and compared with unstimulated controls (Subgroup C). Animals (12 per group) were bled for 7 h at 20-min intervals, starting 3 h before stimulation by oestrous females (3 per group). Eight rams from Subgroup S showed an increase of LH pulse frequency and only 3 in Subgroup N (P < 0·03). In Subgroup S the introduction of females led to 2- and 3-fold increases in LH pulse frequency during the stimulation period compared with values in Subgroup C or before the stimulation period (3, 1·6 and 1 peaks/rams/6 h respectively; P < 0·05). The presence of females also led to an increase in mean testosterone concentrations, and small increases in basal and mean LH values. No differences were found in LH peak amplitudes. In Subgroup N only inconsistent evidence of increases in mean LH and testosterone values was found. No differences between Subgroups S and N in behavioural patterns during stimulation were detected. We conclude that the presence of females affects LH pulse frequency at sunrise but not at noon during the breeding season and this effect is at least partly independent of sexual behaviour. These results suggest a possible circadian variation in CNS sensitivity involving the hypothalamic regulation of LH secretion in response to the presence of oestrous females.Keywords: temporal variations; LH; testosterone; ram; female effect; teasing

Journal

ReproductionBioscientifica

Published: May 1, 1988

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