I think he was either a stallion or a gelding.
The feminine form of stallion is mare. Stallions are male horses, while mares are female horses.
A stallion will mate with as many mare's as are available.
Because the stallion is a male and the mare is a female.
Mare
The stallion's hooves can cut the mare's back, the mare may kick out at the stallion, the mare may even colapse under the stallion's weight.
Beauty was a male, Ginger a mare, Merrylegs was male also.
In most cases, the father of a foal does not play a role in raising or caring for the foal. The responsibility of caring for and raising the foal falls mainly on the mother (mare). The stallion typically continues with his normal activities within the herd or separately.
Mare
A mare.
Mare
Mare
Mare