Research on Qualitative Genes of Poultry in the United States Part 2

Abstract

Nebraska Agricultural Experiment Station, Lincoln, Nebraska 68503Aliniad et nl. (1971) caged dwarf and normal stocks individually in environmental chambers at 22'~' and 3O'C and fed dietary levels of 250 and 350 kilocalories metabolizable energy per 105 grams. The only difference notsd betwcen dwarf and normal stocks was a slight decrease in egg production of dwarf hei?s at the higher environmental teniperatu re.Mather and Ahmad (1971) after acclimation of dwarf and normal laying hens to 22'C for 21 days, abruptly increased the environmental temperature in the c1i:miber to W C for two hours. Both the rectal temperature and respiratory rate iricreased, but the relative increase was less for recta1 temperature rind more for respiratory rate in dwarf than in normal hens. Department of Zoology, University of Nebraska, l,incoln, Nebraska 68503Brumbaugh (1 968) studied the ultrastructural events occurring during melanin formation in the fowl. Melariir; precursors were apparently packed in Golgi vesicles. He then deposited nrelanin upon a premelansonx matrix. The pink-eye ( p k ) mutation rctirrded deposition of the melanin so that the niatrix structure was visible. Brunibaugh and Moore (1 069) deterinined the time of melanocyte tliRerentiation 32 33 in embryos and regenerating adult feathers for three alleles at the E pigment locus in the fowl. In both embryos and adult female breast feathers, extended black (E) melanocytes differentiated early and produced eumelanin. Recessive wheaten (ev) melanocytes differentiated later and synthesized pale phaeomelanin. Wild-type (e+) melanocytes produced a more intense phaeomelanin and differentiated at an intermediate time. Melanocytes in male breast feathers of each genotype differentiated early and produced eumelanin.The dominant white and silver mutants of the fowl were examined ultrastructurally and histochemically in comparison with wild-type pigmented genotypes (Brumbaugh, 197 1). Apparently, the differences in the three phenotypes are explained by differences between eumelanin formation and phaeomelanin synthesis. Brumbaugh et al. (1972) found a new autosomal recessive mutant designated lavender (lav) in domestic fowl. This pigment-diluting mutant is linked with rose comb (R) by 32.5 per cent. Research and Development Division, Hubbard Farms, Inc., Walpole, New Hampshire 03608 Carte and Smith (1969) mated rapid-feathering male chickens from a synthetic line to gold, slow-feathering Rhode Island Red females. The F1 males (SsKk) were backcrossed to the PI females (S-k-), and plumage colours of the slow-feathering female progeny were recorded. The 15 white and 838 gold progeny gave a crossover frequency of 1.8 per cent. New Hampshire Agricultural Experiment Station, Durham, New Hampshire 03824 W. M. Collins, W. R. Dunlop and A. C. Corbett are developing four sublines of New Hampshire Chickens. Each subline will have a different combination of two homozygous gene pairs controlling resistance and susceptibility to leukosis viruses. Collins et al. (1968b) measured egg yolk chol...