Chromosome analysis of early embryonic mortality in layer and broiler chickens.
1. Twenty-three lines of chickens, obtained from grandparent stocks of 4 Australian breeding companies, were analysed to determine the incidence of early embryonic mortality attributable to chromosome abnormalities. The lines included 10 layer strains, consisting of 6 White Leghorn, 2 New Hampshire and 2 Australorp lines, and 13 broiler lines. 2. A total of 10,730 eggs was examined after 3 d incubation; of these 9746 (90.8%) were fertile. Abortive embryonic development was observed in 1379 (14.1%) of the fertile eggs. This consisted of 952 (69.0%) dead and dying embryos, including 646 malformed and 427 (31.0%) membranes without embryos. 3. Early embryonic mortality was found to vary from 9.8 to 26.8% (average 16.4%) in broiler lines and from 8.0 to 27.9% (average 11.9%) in layer lines. 4. Among 898 abortive embryos analysed, 112 had abnormal chromosomes consisting of 27 haploids, 38 haploid-euploids, 24 triploids, 16 diploid-polyploids, 4 aneuploids, 2 tetraploids and 1 translocation. 5. In broilers and layers respectively, chromosome abnormalities were responsible for 4.4 to 28.1% (average 11.8%) and 7.4 to 25.0% (average 13.4%) of the early embryonic mortality. 6. The overall frequency of chromosome abnormalities in all fertile eggs varied from 0.7 to 3.7% for the broiler lines and 0.7 to 3.4% for the layer lines.
CSIRO Division of Animal Production, Poultry Genetics, North Ryde, NSW, Australia.
M H
MH
Thorne
R K
RK
Collins
B L
BL
Sheldon
D000818:Animals; D001947:Breeding; D002642:Chick Embryo / Q000002:abnormalities; D002678:Chimera; D002869:Chromosome Aberrations / Q000453:epidemiology / Q000401:mortality / Q000662:veterinary*; D025063:Chromosome Disorders; D005298:Fertility; D006238:Haploidy; D015994:Incidence; D007621:Karyotyping; D008677:Metaphase; D011003:Ploidies; D011201:Poultry Diseases / Q000453:epidemiology / Q000401:mortality*