HERD INVESTIGATION - A COMPARISON OF MILK-PRODUCTION DURING FIRST LACTATION

Raising replacement heifers is a major-expense. By reducing: the days necessary to feed a replacement heifer, dairy producers can lower the cash outlay needed for feed. On most dairy farms, heifers carve for th e first time when they are older than the recommended age because dair y producers underestimate the correct weight of animals and fail to fo llow a nutritional program that can achieve the recommended height and weight at an early age. We conducted a retrospective investigation th at compared (1) body height and condition to evaluate size at first br eeding and (2) first-lactation production of heifers calving between 2 2 and 33 months of age. Data included the predicted transmitting abili ty of the sire measured in milk pounds, use of bovine somatotropin, pe ak milk pounds, month of peak milk production, age at calving, and fir st-service conception rate. Statistical regressions of the mature equi valent and the actual 305-day production were established. Statistical data obtained from our investigation did not reveal any-disadvantages to calving heifers as early as 22 months of age. Therefore, Veterinar ians should evaluate the replacement programs of clients and determine whether improved rearing conditions would improve the economic return .