Genetic Evaluation of Age at First Calving Data First calving from January 1, 1997 to present

Genetic Evaluation of Age at First Calving

Data

• First calving from January 1, 1997 to present

• Calving ages between 540 and 1105 days

• The cows sire had to be at least 5 years old

• 8,193,513 first calvings

Model

• y = hys + a + e

• y = age at first calving

• hys = fixed effect of herd-year-season of birth

• a = random additive genetic effect

• e = random residual error

Summary Statistics ― Cows currently milking

Summary Statistics ― Active Bulls

Correlations

Correlations (Continued)

Variance Component Estimates

Genetic Trend

Genetic Trend

Low Active HO Bulls

High Active HO Bulls

High and Low Active HO Bulls with > 90% rel

Low Active JE Bulls

High Active JE Bulls

High and Low Active JE Bulls with > 90% rel