A selection index for dairy cows

Abstract
The rationale for a method of computing selection indices for dairy cows is outlined. It uses predicted transmitting abilities of sires from a best linear unbiased prediction or similar method of evaluation together with mean transmitting abilities (cow indices) of dams to estimate herd genetic levels. Indices for individual cows are computed using deviations from those of contemporaries in the herd of her sire's transmitting ability, her dam's index and her own production in each lactation.The method is being used in the UK, cow indices being expressed as transmitting abilities relative to the same fixed genetic base as for sire evaluation.