AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

USES OF REPEATABILITY

• Repeatability estimate sets upper limits to heritability in broad sense. Since repeatability is easier to estimate than heritability we can reasonably guess the probable value of heritability from the estimate of repeatability.
• Repeatability estimates are used to predict future performance from past records. When the repeatability for a trait is high, selection for the trait on the basis of the first record itself would be effective in improving the over-all performance of the herd in the next year.
• Repeatability indicates gain in accuracy expected from multiple measurements. If repeatability is high multiple measurements are not going to improve the accuracy of selection. If repeatability is low then two or more measurements will improve the accuracy of selection because increase in number of measurements reduces V_Et or V_Es that appears in the phenotype variance (V_P), and thus the reduction of V_P represents the gain in accuracy.
• Used to estimate the future performance of animals or Most probable Producing Ability (MPPA). Lush suggested the formula for estimating MPPA using repeatability estimate to adjust the records of cows with varying number of records / observations to uniform basis for comparison during selection programme.

  
• Repeatability estimate also throw light on the nature of environmental variance affecting the trait.