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Genetic Evaluation of A ge 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
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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
Variance Component Estimates HO Heritability = 0.027 JE Heritability = 0.028