Investigation on the frequency of alleles at the k locus and their effect on the growth of two lines of Plymouth Rock chickens.

The research was performed with the goal of establishing the frequency of alleles for fast or slow feathering at the K locus in two lines of White Plymouth Rock hens (maternal forms) -- lines L and K, as well as their influence on the birds' live weight during growth. The rate of feathering was determined at one day of age according to the length of the primary and secondary wing feathers. The birds' weight development was controlled through individual weighing at 2, 4, 6, 8, 10, and 12 weeks of age. In male chickens of the L and K lines, a higher frequency of the slow-feathering allele was found, respectively, 0.676 and 0.503 against 0.203 and 0.306 in females. Male and female chickens of the L line with a rapid-feathering genotype had higher live body weight than those with alternative genotype at ages of 2 to 12 weeks. There were no differences between the feathering genotypes for female chickens of the K line, whereas in males there was a tendency for higher live body weight with the rapid-feathering genotype. Slow-feathering chickens of both sexes of the same line were by 81.20 g (4.10%) lighter than rapid-feathering ones at the age of 12 weeks (p<0.05). The effect of slow- or rapid-feathering alleles was not identical for both sexes and the studied lines. [ABSTRACT FROM AUTHOR]