Synthesis and parameters of new populations of meat-type chickens.

Sire and dam populations of meat-type chickens were developed at the Animal Research Centre, Ottawa to provide unselected control populations suitable for modern broiler research, estimate genetic parameters of broiler traits, and initiate selection experiments. The populations were synthesized from 16 commercial broiler parent stocks (nine sire and seven dam stocks) during two generations of crossbreeding and one generation of random mating. The estimated genetic contribution per stock to the respective population ranged from 8.3 to 16.7% for autosomal genes, from 5.5 to 17.8% for genes on Z chromosomes, and from 0 to 25.0% for genes on W chromosomes. Genetic differences among the original stocks had not been fully diffused among individuals within the populations at the time parameters were estimated. Consequently, genetic parameter estimates are probably slightly biased. Estimated heritabilities of broiler traits in these populations were generally high, 0.39 to 0.63. Hence, rapid genetic change of these traits is possible. The genetic correlation between 28 to 49 day feed efficiency and corresponding weight gain was 0.69 and between feed efficiency and abdominal fat percentage was -0.68. Increasing body weight gain, improving feed efficiency and reducing abdominal fatness of broilers by selection appears feasible.