Lunar Effect on Thoroughbred Mare Fertility: An Analysis of 14 Years of Data, 1986-1999
Titel:
Lunar Effect on Thoroughbred Mare Fertility: An Analysis of 14 Years of Data, 1986-1999
Auteur:
Kollerstrom, N.
Verschenen in:
Biological rhythm research
Paginering:
Jaargang 35 (2004) nr. 4-5 pagina's 317-327
Jaar:
2004-10
Inhoud:
It became possible to access the yearly studbooks of a major UK Thoroughbred studfarm. By comparing these with subsequent published records of horse-breeding, one could compare the coverings between mares and stallions with the outcome as to whether or not a registered conception occurred. The coverings went on seven days a week with no interruption, over the breeding months of early spring and summer, and so offered an opportunity to test hypotheses concerning the lunar phase cycle. Since the studbooks began, vets have been able to detect the onset of estrus every three weeks, so that the covering dates give a fairly unerring record of mare estrus. Two logically distinct parameters were here tested: the extent to which the onset of estrus was related to the lunar month, and then whether the proportion of successful coverings varied with the lunar month. A total of 14 successive years of studbook data was recorded and tested in this manner, partly to average out irregularities in lunar angular speed resulting from the apogee-perigee cycle (linked to the 9-year apse cycle) and partly to be able to investigate whether the 18.6-year nutation cycle would affect the way in which the lunar-month cycle worked. This notion came from geomagnetic surveys, which have showed a sizeable modulation of the geomagnetic field with the synodic cycle, with the modulation of this by the lunar-node cycle. The notion of an influence of the synodic cycle being modulated by the 18-year nutation cycle is supported by the present enquiry. One could choose to view this as, effectively, a 9-year cycle, insofar as no distinction was here made between the two lunar nodes. The method employed five successive lunar-days (one-sixth of the lunar month) to investigate the peaks and troughs of the synodic cycle.
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