Symposium review: An abundance of replacement heifers: What is the economic impact of raising more than are needed?

Historically, most dairy producers raised every heifer born, to ensure a supply of future replacements. However, advancements in transition and reproductive management, coupled with widespread use of sex-sorted semen in dairy heifers and cows, have led to an oversupply of dairy replacement heifers in the United States. With current market values for prepartum heifers at 1, 300 and estimated raising costs ranging from 1, 700 to 2, 400, dairies that continue to produce quantities of heifers in excess of anticipated needs with plans of selling the extras on the open market are likely to experience significant economic loss. Adult cow herd turnover is the key driver behind the number of heifers needed to calve; however, mortality, disease, fertility, and elective culling losses throughout the heifer-raising period determine the total number of heifers that must be retained and raised to meet anticipated needs. A convenience sample of 50 US dairy herds revealed an average heifer inventory of 102% of total milking and dry cows. In this data set, the mean annualized adult herd turnover was 39%. With a mean stillbirth risk of 5. 7% in calving heifers, a culling risk of 10. 2% by 13 mo of age, a reproductive failure risk of 6. 8% in breeding heifers, and an additional culling risk of 6. 4% in pregnant heifers, only 74% of calving events with a heifer birth yielded a heifer that entered the lactating herd. Much of this heifer removal was elective, and making the correct culling decisions at the appropriate time yields the best return for the herd. To demonstrate how a herd might approach the elective culling issue, a records-based exercise with 2 large Holstein herds was performed to estimate the cost versus benefit of 3 different elective culling approaches, using a combination of genetic potential and growth performance as the selective criteria. However, the culling of heifers results in economic losses, because the revenue received is less than the cost incurred during raising. Selective culling of heifers soon after weaning yielded the best results in both herds, but despite the predicted improvement in lactation performance of the retained group, the cost associated with removal was greater than the benefit predicted. Culling a group early and then culling a second group just before calving yielded the largest loss. Moving forward, herds should breed more carefully to produce better-quality heifers from more superior dams and sires and consider the use of beef semen in inferior animals. However, to reduce the risk of not producing an adequate supply of replacement heifers, dairies should add an additional buffer to their anticipated needs. Using the assumptions within this project, having 10% extra calving events with a heifer birth would allow the annualized adult herd turnover to rise from 39 to 43% in case economic conditions or health status of the herd should change. If these heifers are not needed, the selection criteria outline could be used to help identify more valuable animals to retain.