Prediction of Average Daughter Performance from Sire Proofs for Use in Linear Programming Sire Profit Models

Abstract

When linear programming is used to rank sires on daughter profits, coefficients of input are required for representative daughters of each sire. Within herd-year-season regressions of daughter's actual 305-day milk, fat percent, days open, 2-min milk yield adjusted for total yield, total milking time, and body weight at birth and first calving on sire's proofs for production, conformation, milking speed, and nonreturn rate were computed from progeny data from 71 Canadian Holstein-Friesian artificial insemination sires, to provide these coefficients. Coefficients of determination for prediction equations were .23 to .71. A production function was fitted for milk production and days open. First lactation 305-day milk was predicted from sire's milk rating and linear and quadratic terms of size ratings. Fat percent proof and its squared term predicted daughter's fat percent. Days open was predicted by milk and fat proofs. Milk yield in the first 2-min of milking, adjusted for milking yield, was predicted by proofs for milking speed and the quadratic term for fat percent. Total milking time was obtained from 2-min yield by regression (−.3837) of total milking time on 2-min yield. Daughter's body weight at first calving was predicted from sire's size proof, as was birth weight. Milk yield was curvilinearly associated with days open. Incidence of mastitis was derived indirectly from regression (.00172) on sire's milk proof for milk.