When do first-time calving heifers start to lactate?

The process by which a mammal begins to produce milk is known as lactation. In first-time calving heifers (also called primiparous heifers), lactation typically begins a few days before or after the heifer gives birth (parturition). The exact timing of lactation onset in heifers can vary depending on several factors, including genetics, breed, health status, and environmental conditions.

Generally speaking, first-time calving heifers start to lactate within a few days of parturition. This process is triggered by hormonal changes that occur during late pregnancy and around the time of birth. The most significant hormones involved in lactation are estrogen, progesterone, oxytocin, and prolactin.

Estrogen and progesterone levels decrease significantly after the heifer gives birth, while oxytocin and prolactin levels increase. These hormonal changes signal the mammary glands to start producing milk.

However, it's worth noting that lactation may not be fully established immediately after parturition. It may take several days for the milk production to reach its peak. During the first few days, heifers may produce colostrum, which is the thick, yellowish-white substance rich in antibodies and nutrients that provides essential nutrition to the newborn calf.

Farmers and livestock producers closely monitor the onset of lactation in first-time calving heifers to ensure they have a successful and productive lactation period. Proper nutrition, management, and healthcare support are crucial for promoting optimal milk production and the health of both the heifer and her calf.