Further Studies With Hens Producing a High Incidence of Non-Calcified or Partially Calcified Egg Shells

Abstract

Two experiments were conducted in which physical and chemical comparisons were made between hens producing a high or low percentage (40 and 4, respectively) of ultra-thin shell (UTS) or shell-less (SL) eggs to obtain information related to the cause of shell-less eggs. No difference was observed in the weight of the hen, egg, ovary or oviduct or in serum calcium or sodium between the UTS-SL hens and control hens. The hens producing a high incidence of shell-less and ultra-thin shell eggs (UTS-SL hens) consumed 2.6 grams less feed per hen per day, and the specific gravity of hard shell eggs was only slightly lower than that of controls. The mixed excreta of the UTS-SL hens contained significantly less sodium and potassium, and 15% more calcium than did the control hens. Tibia weight, breaking strength and ash was significantly greater in the UTS-SL hens. No difference was observed in calcium content of the isthmus and magnum but the uterus of the UTS-SL hens contained a significantly higher percent calcium than that of the control birds. Percent fat in the uterus was significantly increased. Percent fat was significantly increased in the liver (Exp. 1) of UTS-SL birds in Experiment 1 and numerically lower in Experiment 2.It was concluded that the inability of the UTS-SL hens to continuously produce eggs with normal shells is not due to a failure of the hen to absorb calcium from the digestive tract, transport it to the blood, bone or uterus but to the hens inability to utilize calcium at the actual site of egg shell formation or premature expulsion.