Optimal use of nucleus and testing capacity in a pig breeding system with sire and dam lines

Abstract

In the short term, the total nucleus and testing facilities of a pig breeding organization are fixed, but distributions over sire and dam lines can be varied. The objective of this study was to optimize these distributions. The effects of alternative distributions of nucleus places for sows and testing capacity for boars on total selection response (i.e. sum of the response for reproduction traits in the dam lines and the arithmetic mean of dam and sire line responses for production traits) were studied with a semi-deterministic model. Parameters used in this model were derived from stochastic simulation studies. Annual number of breeding boars was 20 in sire lines and 40 in dam lines. Conclusions (for four-way crossbreeding systems) were as follows: (1) the optimum ratio of sow places for sire lines to sow places for dam lines was about 1:2; (2) the optimum ratio of boar testing capacity for sire lines to boar testing capacity for dam lines was about 1:1; (3) the optimum ratios depended on the total testing capacity relative to the total number of sow places in the nucleus. They were also sensitive to testing system (number of boars tested per litter). Culling rate of boars after test (for conformation or semen quality), crossbreeding system (three-way vs. four-way cross) and annual number of breeding boars had little influence.