A strange creature with smooth pale gray skin and narrow legs with large hooves that only comes out of it’s burrow during a full moon. It’s eyes are very large and bulgy, they sit on the top of it’s head. It’s enormous flat hind feet leave intricate impressions on wheat fields when it dances (much to the confusion of Muggles). This is also believed to be a part of a Mooncalf mating ritual. Mooncalf dung that is harvested before the sun comes up makes a powerful fertilizer (FB).
The Mooncalves in Newt Scamander's case eat Mooncalf pellets (WFT). In turn, Mooncalves are a favorite prey of the Hodag (FB).
Historically, "mooncalf" refers mainly to a miscarried and usually deformed fetus of a cow or other animal. Occasionally, it was applied to similar human cases, as well. It refers to the belief that the cycle of the moon had adversely affected fetal development in these instances (source: Wikipedia). -BB