The Association of Lunar Phases on Calving in Montbéliarde Dairy Cows in the Franche-Comté Region, France

The Moon is at the centre of many popular beliefs including that the number of births increases during Full Moon days, followed by many breeders to anticipate calving periods. However, it has been rarely explored in dairy cattle farming. This retrospective study was conducted to evaluate the association of lunar cycles on calving distribution, with particular focus on a potential increase during full-moon nights. Data from 383,926 calvings of Montbéliard breed that occurred between March 2022, and January 2025, mostly in Franche-Comté (98.2%), France were analyzed. Statistical analysis was performed using the Generalized Linear Mixed Model (GLMM). Results revealed significant association of the lunar cycle on calving distribution, it was observed a higher calving probability than the average (p < 0.001, +15%) during the New Moon, and a lower calving probability than the average during the First Quarter and Full Moon phases (p < 0.001 for both and -1.5% and -11%, respectively) in all groups, primiparous, multiparous, male and female. The observed patterns may have practical implications for veterinarians and breeders, particularly in ensuring adequate colostrum intake, thereby supporting improved management of parturition periods.