“…Many factors have been shown to influence eCG concentrations in mares’ blood, including mare size (8,60,61), mare parity (62), paternity of the conceptus (63), twin pregnancy (64), and conception at the first postpartum oestrus (65). More recent experiments, in which mare size, age, parity, and conceptus paternity were standardized, have also shown that both body condition and exercise have a significant influence on eCG concentrations in maternal blood(66).…”