Plasma Estrogen, Calcium, and Shell Quality in Two Strains of White Leghorns

Levels of plasma estrogens and total calcium were studied during the second laying year in two high performance strains (1 and 4) of White Leghorns approximately 6 to 8 hr after oviposition. Each strain had been divided into two groups, those that had laid eggs with high and those that had laid eggs with low specific gravity during the first laying year. Strain 1 had significantly (P<.01) greater levels of plasma estrone, estrone sulfate, and estradiol but not estradiol sulfate or total calcium than Strain 4. The high specific gravity group had higher levels of plasma calcium and only a tendency (P>.05) for higher plasma estrogen levels than the low specific gravity group.