The researchers used a full diallel cross to study genetic variability in chickens and determine the best breeding methods for improving productivity. They looked at general and specific combining ability, as well as maternal effects, in different strains and breeds of chickens. The study found that certain economic traits in pullets were influenced by both general genetic factors and specific interactions between parental strains. This information can help breeders make informed decisions about which crosses are most likely to produce desirable traits in their chickens.