In this paper a method is outlined to derive marginal-income functions
and to calculate economic values for traits with an intermediate opti
mum such as meat-quality traits. A normal distribution of the quality
trait was assumed, but the method can be used for other distributions
as well. The parameters necessary to use this method are distribution
of the quality trait, population mean and the standard deviation of th
e quality trait, optimum range, and price differences between products
within and outside the optimum range. Especially, the optimum range f
or the quality trait and the price differences to be used have to be d
erived from consumer and processing research. Some alternative methods
that can be used for selection on quality traits, such as restricted
selection index, desired-gains index, and indices based on a quadratic
aggregate genotype, are discussed.