Does a heifer still mate when pregnant?

Yes, a heifer can still mate while pregnant. This condition, known as superfetation, occurs when a female animal becomes pregnant while already carrying a pregnancy from a previous conception. Superfetation can occur in heifers and other species, including sheep, goats, and rabbits.

In superfetation, a new pregnancy is initiated while the corpus luteum from the previous ovulation is still present. This means the heifer has multiple corpora lutea in one ovary. The new conception typically occurs within a few days or weeks of the first pregnancy.

The mechanism that allows for superfetation in heifers is not fully understood, but it is thought to be related to hormonal factors. In some cases, superfetation can occur when a heifer experiences anovulatory cycles or has multiple ovulations during a single estrous cycle.

Heifers that are pregnant with twins or more can also undergo superfetation, resulting in multiple pregnancies with different gestation lengths and developmental stages.

Superfetation can pose risks and challenges for the heifer and her offspring. The additional pregnancy can strain the heifer's resources and nutrient requirements, leading to potential health complications for both the mother and the existing pregnancy. Managing superfetation may require modifications to nutrition and care for the heifer to ensure the successful development and health of all pregnancies.