Phenotypic Correlations of Certain Turkey Egg Parameters

Pedigreed eggs from turkey hens were cut in half lengthwise with a small high-speed drill with a circular saw attachment. The membranes were peeled out of the shells and placed in an Allo Kramer shear press. The shells and membranes were measured for thickness using a paper thickness gauge. All eggs were weighed and measured for specific gravity. Hatchability was calculated from other eggs laid by the same hen. Hatchability was higher with a membrane of lower weight, with a higher pressure per gram required to shear the membranes and with a thinner membrane at the larger end of the egg. The membranes averaged 0.060, 0.040, 0.049 and 0.049 mm. in thickness at the larger end, the small end and the two sides of the egg, respectively. The correlation of hatchability with specific gravity and the measured shell thickness on the sides of the egg approached significance and was negative. The shell thickness averaged 0.385, 0.415, 0.370 and 0.373 mm. at the larger end, the small end and the two sides of the egg, respectively. Eggs which had thinner shells at the site where the poult emerges from the shell were inclined to have higher hatchability. The membrane and shell thickness in different areas of the egg were not greatly variable as was shown by the high correlations among the different areas of shell thickness and membrane thickness. Repeatability of the parameters measured were in the medium high range.