Optimum selection procedures in animal breeding

Abstract

SUMMARY: A simple expression relating the standardized selection differential (i) to the intensity of selection (p) is given byi≏0·8+0·41 ln (R−1)where R equals 1/p. This linear expression may allow simpler solutions to some optimization problems in selection than does the conventional formula for selection differential on truncation of the normal curve.Using the expression, formulae for the maximum immediate response and optimum selection intensity in mass selection have been developed, taking account of the loss in performance through inbreeding. These formulae were used to study the effect on response of the total number of animals tested. The maximum response over a specified period of time, allowing for the loss in genetic variance from inbreeding, has also been considered. The optimum intensity of selection may then be well below that necessary for the maximum immediate response.