Genetic parameters for a simple predictor of the lifespan of Holstein-Friesian dairy cattle and its relationship to production

摘要: The herd life of dairy cows was approximated by a single lifespan value based on the geometric distribution and accounting for number lactations each cow had completed or, if still in herd, expected to complete. For which lactation n, but not time complete n + 1, probability survival from 1 2 etc. incorporated, utilizing average population probabilities.Formulae genetic variance lifespan, its heritability regression breeding phenotype, latter found be independent amount information included are derived checked simulation.From an analysis 25227 cows, with opportunity five lactations, 0·06 correlation three, four ranged 0·90 0·96, both incomplete information, showing that trait appears account adequately missing observations. Genetic correlations between first yield traits were around 0·50, whilst corresponding phenotypic approximately 0·13.