Calves & Heifers

It is well-known that acquiring and absorbing adequate amounts of colostral immunoglobulins are essential to the health of the neonate, since calves are born almost void of any circulating antibodies. Colostrum is defined as the first milk harvested from the cow immediately after calving.

Physiology of the preruminant calf
Water makes up 85.8 percent of the bodyweight (BW) of a neonatal calf. Prior to birth, the developing fetus is surrounded by amniotic fluid that is 92 percent water. In the uterus, the developing calf is supplied with water by diffusion from maternal plasma, and at birth the calf is at its greatest water content, having developed in a water-based media where water has borne the nutrients required to allow rapid growth and development.

A lot of work and care is required to develop newborn calves into productive, lactating cows. When managed properly, replacement heifers should grow at a rate that allows them to calve at 24 months of age or less. However, a recent report indicated the average age of Holsteins at first calving was 26.9 months, so there are opportunities for improvement. Also, the mortality rate on many farms is higher than desired, reducing the number of potential replacement heifers.