- Maturity in ruminants is weight and age dependent
- The onset of puberty in heifers depends on weight and rate of growth
- Exotic animals reached maturity earlier at 40% mature weight and indigenous at 60% mature weight
- Target weighs for the first service depend on breed, but should be higher than that at which the heifer achieves puberty and first estrus.
- A low age at first calving is desirable because it reduces land and forage requirements for replacement stock and reduces overall maintenance costs for young stock. It also leads to faster genetic improvement as a cow will have more calves in its lifetime.