Fordicidia April 15

, the month of April (Aprilis) was generally concerned with female or ambiguously gendered deities, opening with the Feast of Venus on the Kalends. Several other festivals linked to farm life took place in April: Parilia, shepherds' festival, on April 21; Robigalia on April 25, to protect crops from downy mildew; and Vinalia, one of the two wine festivals in the calendar, at the end of the month.

Among these, the Fordicidia and Robigalia are likely to have been of the greatest antiquity. William Warde Fowler, whose early 20th-century work on Roman festivals remains a standard reference, asserted that the Fordicidia was "without doubt one of the oldest sacrificial rites in Roman religion."

The Fordicidia was named after the Fordae cows; a forda cow is one that carries an unborn calf; as on that day several pregnant cows were sacrificed officially and publicly in the curies, the festival was called the Fordicidia de fordae caedendae, “the pregnant cows which had to be slaughtered”.

The forms horda and Hordicalia are also found. Like many other aspects of Roman law and religion, the institution of the Fordicidia has been attributed to Numa Pompilius, the second Sabine king of Rome. The rustic god Faunus instructed Numa in a dream that a sacrifice to Tellus would alleviate the harsh agricultural conditions facing Rome, but the oracular message required interpretation: "By the death of cattle, king, Tellus must be appeased: two cows, which A single heifer gives two lives (animae) for the rites." Numa solved the riddle by instituting the sacrifice of a pregnant cow.

As with other rituals in which public worship was mirrored by private worship, or vice versa, one sacrifice was performed in the name of the state, in this case at the Capitol, and one in each of the thirty curias, the divisions most oldest in the city. made by Romulus from the three original tribes. It was the first of two festivals involving the curiae, the other being the Fornacalia of February 17, which differed in that there was no state ritual corresponding to the local ceremonies and its movable date was fixed annually by the curio maximus.

In the state sacrifice for the Fordicidia, the unborn calf was torn from its mother's womb by the attendants of the Virgo Vestalis Maxima, or Vestal Maxima, and burned. Her ashes were preserved by the Vestal Virgins and used as one of the ingredients of the ritual substance suffimen, along with the dried blood of the horse from October of the previous year and the stalks from which the beans had been harvested. 

The suffimen was sprinkled on the bonfires of Parilia, the festival dedicated to the purification of shepherds and their sheep, and later also celebrated as the "birthday" of the city. The sacrifice at the Fordicidia and the preparation of the suffimen constituted the first public ceremony of the year in which the Vestal Virgins played an active role.