Use of computerized mate selection programs to control inbreeding of Holstein and Jersey cattle in the next generation

The expected role of computerized mate selection programs with regard to in breeding and lifetime profitability of Holstein and Jersey cattle was exami ned using data from 25 large registered herds of each breed. Sire selection and mate allocation were carried out using linear programming with the fol lowing objectives: 1) minimum inbreeding, 2) maximum net merit subject to a fixed inbreeding threshold, and 3) maximum expected lifetime profit after adjustment for inbreeding depression. Inbreeding of actual matings was simi lar to inbreeding from random matings, indicating that current inbreeding a voidance programs in these herds are ineffective. Inbreeding was reduced by 1.6 and 1.9% in Holsteins and Jerseys, respectively, when a mate allocatio n program was applied with service sires and usage levels fixed at the actu al values. Benefits of mate selection programs increased when both sire sel ection and mate pair allocation were considered. Maximization of mean net m erit with inbreeding restricted to a fixed level (5% in Holsteins and 8% in Jerseys) led to decreases in inbreeding of 0.9 and 1.4% and increases in l ifetime profit of $16.66 and $26.86 in Holsteins and Jerseys, respectively, relative to programs that ignored inbreeding. Maximization of mean expecte d lifetime profit after adjustment for inbreeding depression decreased inbr eeding by 1.8 and 2.8% and increased lifetime profit by $37.37 and $59.77 i n Holsteins and Jerseys, respectively. Inbreeding coefficients estimated wi th pedigree traced to 1985 were inadequate predictors of inbreeding coeffic ients estimated with pedigrees traced to 1960. Mate selection programs cann ot function optimally unless extensive historical pedigree data are availab le, particularly for service sires. Computerized mate selection programs ca n reduce inbreeding in the next generation, which will lead to an increase in farm profitability. However, if genetic diversity is to be maintained in the long term, procedures for selecting parents of AI sires must also be c onsidered.