Replacement Management in Cattle | Breeding Standards and Pregnancy Management

Rearing replacement heifers is part of herd survivability and represents 15–20% of total farm costs. Proper attention to the growth of heifers is paramount to producing heifers that achieve adequate stature and body weight before first breeding and calving. Timely entry of heifers into the milking herd by 2 years of age, or their first eligible calving season in seasonal pasture-based dairy enterprises, can be facilitated by applying synchronization of estrus and ovulation in addition to traditional detection of estrus by visual or other means. Because fertility is better in heifers than in lactating cows, artificial insemination of heifers with semen from the best available progeny-tested bulls is a wise investment to ensure genetic gain of economically important traits. Annual culling rates of 25–33% necessitate a supply of herd replacement heifers. Application of gender-biased semen to produce more female offspring is also warranted for increasing the replacement population. The main goal of a heifer replacement program is to develop heifers at minimal cost and in a timely manner to obtain heifers of desired size and body weight so that they attain puberty, establish pregnancy, calve easily, and achieve their maximum genetic lifetime milk production as cows.