Genetic response to index selection for the improvement of egg production efficiency in layer-type chickens

Abstract

<p>Recording individual feed consumption in layer-type chickens is costly. For this reason, feed record information in most commercial breeding programs is omitted. The present study focuses on the evaluation of feed records to improve egg production efficiency in two populations of Leghorns. From four generations of index selection based on body weight, egg mass and feed consumption information, sexual maturity was delayed, egg size and daily egg mass output increased and feed efficiency (egg mass/feed consumption) improved. On the other hand, selection on an index containing information only on body weight and egg mass, increased body weight, egg weight, daily egg mass and feed consumption, but it failed to improve feed efficiency. The preliminary results, therefore, indicate that feed record information aids in improving the efficiency of feed utilization;The selection responses obtained in two different populations of Leghorns were frequently inconsistent for several traits. This may have been due to an incorrect choice of the economic value constant for body weight in the selection indexes used in the two initial generations of selection. A contributing factor might have been a poor choice of parameter estimates taken from the literature which were needed to solve the index normal equations. It is concluded that to establish superiority of an index containing feed record information, additional generations of the selection experiment would be required. Data of the latest generations available might then be used to obtain better estimates of parameters needed to solve the index equations.</p>