Studies on the Cause, Prevention and Artificial Creation of Pimpled Egg Shells

Abstract

Six experiments were conducted to determine the cause, prevention and artificial creation of pimpled egg shells as well as the relationship of the hen’s age to the incidence or severity of pimples. The results from these studies indicated that there were at least two major types of pimpled shells. In the first type, pimples were attached only to the exterior surface of the shell and were easily removed. The entire pimple was 30.68 ± 1.93% calcium. In the second type, pimples were attached to the egg at any point between the shell membranes and the exterior surface of the shell. By carefully removing the outer shell from the top of the second type of pimple, a cavity containing a brownish-white powder-like substance was observed. This material was 31.83 ± 0.45% calcium. The uterus and isthmus of birds laying pimpled eggs also contained material very similar to that found in the cavity of pimples. The material in the uterus and isthmus was 14.23 ± 0.37% and 24.03 ± 1.26% calcium, respectively. The introduction of 0.1N HCl into the uterus of hens producing eggs with pimples did not reduce the incidence or severity of egg shell pimpling; however, it was found that pimpled egg shells could be artificially created by the introduction of approximately 1.5 grams of CaCo3 into the uterus of hens. Holding hens out of production for approximately 2 1/2 weeks by feeding potassium iodide had no influence on the incidence of pimpling. Results also indicated that the degree of pimpling of egg shells from an individual hen remained fairly constant from day to day, but the severity of pimpling increased as the bird aged.