Identification of a 16--17-day lethal factor in a chondrodystrophic stock of turkeys

Chondrodystrophy in turkeys is a lethal condition produced by an autosomal allele, ch. Mutants are characterized by very short and thick legs, shortened wings, globular head with parrot beak, and a protruding abdomen. Classification of ch/ch embryos may be accurately made at 12 days incubation, prior to which limited appendicular development precludes distinction from normal or heterozygous birds. Death caused by the mutant allele occurs between 24 and 28 days; some embryos are alive but unpipped at time of hatch. Analysis of the pattern of embryonic mortality for the stock carrying the ch allele revealed at 16--17-day lethal factor that appears to be independent of chondrodystrophy. Of 52 females mated to Ch/ch males, 41 were determined to be Ch/ch; 32 of these heterozygous females exhibited normal embryonic mortality patterns. Nine hens, in addition to being Ch/ch, displayed a significant increase in embryo death between 15 and 18 days, peaking sharply at 17 days. Of the 11 females determined to be Ch/Ch, five showed the same 15 to 18 day pattern of mortality observed for the nine Ch/ch females.