Relationship between actual vs. targeted weight at first calving and milk production in first and second lactation

Abstract

First lactation milk production is affected by management dur­ing the raising period prior to first calving as well as during lactation. Genetics, feeding, breeding, health and other issues combine to determine the size and age at first calving. Com­monly stated goals for raising replacement heifers include a first calving age of approximately 23-24 months and 82-85% of expected mature body weight. The objective was to quantify the relationship between differences in actual vs. targeted weight at first calving and subsequent 305d milk production.