Why heifer maturity matters

“The Peter Pan Problem”

Abstract

Evaluation of dairy farm records from across the United States revealed an interesting, yet not surprising, pattern: heifer immaturity appears to have a significant and lasting adverse impact on future milk production. This impact manifests primarily in the first and second lactations, but may persist beyond the third lactation. Initial observations used the age of calving as a proxy for maturity. Further review of a large number of dairy herd records revealed key observations: 1) average annual herd milk production approximates Week 10 milk of first-lactation animals; 2) there is a fixed relationship (difference of 30 lb; 13.6 kg) between lactation 1 and 2 at Week 5 milk; and 3) age at calving impacts lactation 1-3. By implication, it is imperative that the heifer raising enterprise utilize objective parameters, such as body weight, to manage the process so that the heifers attain desired maturity at calving to achieve maximum lifetime milk production.