A Test of the Reciprocal Recurrent Selection Technique With Chicken Broilers

The reciprocal recurrent selection technique for improving combining ability was tested with two strains of chickens. Body weight of broilers was the criterion. Selection was based on the 10-week body weights of crossbred progeny but only selected individuals from the purebred strains were used as parents of succeeding generations. Random-bred control strains, in which no selection was practised, were also maintained and reproduced to assist in evaluating genetic change in the selected strains.Reciprocal recurrent selection brought about a progressive increase in the body weight of both purebred and crossbred broilers from the strains under selection. Broilers from the selected strains were 11.3 per cent heavier at 10 weeks of age than those from their unselected counterparts at the end of the experiment. Broilers from the control strains maintained a nearly constant weight. Purebred broilers from the selected strains increased in weight as the experiment progressed, at approximately the same rate as crossbreds from the same strains. Selection apparently resulted in an accumulation of genes having an additive favorable effect on body weight, but it failed to improve combining ability. Over-dominance and/or epistasis did not appear to be important factors in heterosis for body weight in these populations.