Is pregnancy length in Martina Franca jennies influenced by lunar cycle?

In humans and animals there is a popular belief that spontaneous parturition, and therefore pregnancy length, could be influenced by the lunar cycle, but results from humans are often impaired by multiple variables of the studied population. In domestic animals those problems can be limited by studying restricted population, such as a single breed, reared under uniform conditions. The present study aimed to assess the possible influence of the lunar cycle on pregnancy length in Martina Franca jennies belonging to a single breeding farm. The retrospective study was performed on data collected from 96 Martina Franca healthy jennies with a normal singleton pregnancy course. The present study showed that, whit lunar cycle divided in 4 lunar phases, neither lunar phase at ovulation, nor lunar phase at foaling significantly influenced pregnancy length (371.8±6.45 days). Pregnancy length was not significantly influenced also by the month of the year in which ovulation and spontaneous foaling occurred, as well as by jennies’ age and foal’s sex. In conclusion, pregnancy length in Martina Franca jennies is very variable (335-395 days) but does not seem to be influenced by lunar phases at ovulation or at foaling, month of ovulation and foaling, and by jennies’ age and foal’s sex. Further studies are needed to clarify the reasons for this pregnancy length variability in Martina Franca donkey breed.