A lunar cycle in mare fertility

Author: Nicholas Kollerstrom
Abstract: An earlier article (Kollerstrom and Power, 2000) presented evidence that the full moon had an effect upon the fertility of thoroughbred mares (as used for breeding of racehorses).Here a further data-set from the same breeding station is here used to complement the original findings. These showed that there were peaks and troughs both in the likelihood of conception (‘fertility’) of the mares, and in the number of ‘coverings’ i.e. mating-pair events at the studfarm, at specific parts of the lunar month. The peak occurred around or just after the Full Moon. The data was taken from studbook records over fourteen consecutive years, 1986-1999 all from one single studfarm, in Newmarket UK. In all, 2318 mating-pair events are here examined. The results show that, while there is a dominant three-week rhythm in mare fertility that is endogenous, i.e. the estrus cycle, there is also a monthly, exogenous rhythm relating to the lunar cycle, which is significant for fertility and could be large enough to be of practical relevance. This article puts forward the evidence for this lunar-monthly effect.
Keywords: Thoroughbreds, mare fertility, conception, moon, lunar month
Publication: Correlation, journal of research in astrology
Issue: Vol 27 number 2
Dated: July 2011
Pages: 39-54

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