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A note on the effect of exposing gilts to a mature boar at 140 days of age

Published online by Cambridge University Press:  02 September 2010

J. S. Walton
Affiliation:
Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Abstract

Fifty-six Landrace ♂ x Yorkshire ♀ gilts were divided at 140 days of age into four groups in a 2 x 2 factorial design whereby they were exposed continually (BE) or not exposed (NE) to a mature boar and were or were not blood sampled twice weekly for progesterone determinations.

There was no effect of BE on the age at the first or second ovulation. Since detection of oestrus was only 70·80% accurate, BE apparently delayed the onset of first and second oestrus by 16 days (p = 0·06). Blood sampling advanced first oestrus by 15 days (F = 0·07) and second oestrus by 32 days (P = 0·001).

The results suggest that gilts are unlikely to be responsive to boar exposure at 140 days of age, that observations of oestrus alone may be a misleading end-point of the effect of boar exposure and that the use of blood sampling for the measurement of progesterone as an index of ovarian activity may attenuate the response to stimuli intended to advance puberty in the gilt.

Type
Research Article
Copyright
Copyright © British Society of Animal Science 1985

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References

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