Design Of Breeding Programs Research Articles

231. Note: Optimum Experimental Designs for Realized Heritability Estimates

Estimates of heritability (i.e., the ratio of additive genetic variance in a population to total phenotypic variance), are necessary for the design and evaluation of breeding and selection programs. Such estimates are usually based on familial relationships within a population (Falconer [1960]; Robertson [1959]). Occasionally, however, especially when generation intervals are short, the heritability (h2) of a trait can be estimated from data obtained in the course of a selection experiment by means of the estimator h2 R/D (1) where R (the total response to k generations of selection) and D (the cumulative selection differential) are defined as follows. Let M, be the phenotypic mean of the entire population under selection in the jth

A note on heritability of live-weight-for-age in Israel-Friesian dairy bull calves and its genetic correlation with milk production

The design and evaluation of breeding programmes for live-weight-for-age (LFA) in dairy cattle requires estimates of the heritability and the additive genetic and residual components of variance for this trait, and also of its genetic correlation with milk production. A number of estimates of these parameters are available (summarised recently by Langelet, 1963; Mason, 1964; and Nichols and White, 1964). They are, however, generally based on rather limited data, on data from cows rather than bull-calves, or on data from dual purpose cattle. In this note estimates of the variance components and heritability for LFA in dairy cattle bull calves, and of the genetic correlation between bull calf LFA and milk production will be presented.