Use of Computerized Mate Selection Programs to Control Inbreeding of Holstein and Jersey Cattle in the Next Generation

Abstract

The expected role of computerized mate selection programs with regard to inbreeding and lifetime profitability of Holstein and Jersey cattle was examined using data from 25 large registered herds of each breed. Sire selection and mate allocation were carried out using linear programming with the following 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 similar to inbreeding from random matings, indicating that current inbreeding avoidance programs in these herds are ineffective. Inbreeding was reduced by 1.6 and 1.9% in Holsteins and Jerseys, respectively, when a mate allocation program was applied with service sires and usage levels fixed at the actual values. Benefits of mate selection programs increased when both sire selection and mate pair allocation were considered. Maximization of mean net merit 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 lifetime profit of $16.66 and $26.86 in Holsteins and Jerseys, respectively, relative to programs that ignored inbreeding. Maximization of mean expected lifetime profit after adjustment for inbreeding depression decreased inbreeding by 1.8 and 2.8% and increased lifetime profit by $37.37 and $59.77 in Holsteins and Jerseys, respectively. Inbreeding coefficients estimated with pedigree traced to 1985 were inadequate predictors of inbreeding coefficients estimated with pedigrees traced to 1960. Mate selection programs cannot function optimally unless extensive historical pedigree data are available, particularly for service sires. Computerized mate selection programs can 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 considered.

Genetic basis and inbreeding in the Brazilian Guzerat (Bos indicus) subpopulation selected for milk production

“…Although the Dairy Guzerat Breeding Program has been started recently (1994) and the sex ratio is increasing (Table 1), these results might be due to the introduction of sires of other origins and proposals, e.g. from the beef herds, into the herds by artificial insemination rather than the use of sires from the herd itself, in addition to the planned mating practice carried out in most herds (Weigel and Lin, 2000;Caballero and Toro, 2002;Colleau et al, 2004). Mating plans that minimize coancestry among pairs represents a robust tool to maximize N e (Caballero and Toro, 2002).…”

“…A simulation study based on Zebu MOET nucleus population parameters reported a trend of increasing inbreeding coefficients along selection generations due to the high frequency of mating among related animals (Peixoto et al, 2005). Weigel and Lin (2000) and Colleau et al (2004) stated that mating plans are an important tool to manage genetic variability. Furthermore, the effects of inbreeding depression may decrease animal fertility and survival, as well as the rate of genetic progress (Falconer and Mackay, 1996;Hill, 2000).…”

Approaches to the management of inbreeding and relationship in the German Holstein dairy cattle population

“…Weigel and Lin (2002) used the method of Meuwissen (1997) and constrained the level of inbreeding in the next generation and found that the optimal number of bull sires and bull dams decreased as the inbreeding constraint increased, particularly at low levels of inbreeding. Weigel and Lin (2000) compared the weighted mean lifetime net merit and the weighted mean adjusted lifetime net merit of the selected group. The weighted mean lifetime net merit after adjustment to zero using a cost factor of $23 per 1% inbreeding as proposed by Smith et al (1998) was highest at an intermediate level of inbreeding.…”

An economic impact of inbreeding in the purebred population of Pinzgau cattle in Slovakia on milk production traits

“…Kadlečík et al (2004) evaluated alternatives of breeding program in the Slovak Pinzgau population according to the achieved level of inbreeding. Effective tools dealing with and managing inbreeding in cattle populations providing a given genetic gain at a fixed inbreeding rate by optimizing long-term genetic contributions of ancestors were presented by Bijma and Wooliams (1999) or Weigel and Lin (2000). Long-term selection responses in dairy herds were also compared by Šafus and Přibyl (2005).…”