INFLUENCE OF THE SPECIFIC GRAVITY OF HENS' EGGS 
ON FERTILITY, HATCHING POWER, AND GROWTH 
OF CHICKS 1 
By F. E. Mussbhl, Professor of Poultry Husbandry, and D. L. HaebERSEEBEN, 
Student Assistant , Nebraska Agricultural Experiment Station 
Several interesting theories have been advanced as to the influence 
which the specific gravity of the hens* egg may have on its fertility, 
hatching power, and the subsequent growth of chicks hatched. Devices 
for the purpose of determining specific gravity of eggs are being dis¬ 
tributed, claims being made that the hatching power of eggs is directly 
related to their specific gravity. 
Experimental work for the purpose of studying the principles involved 
rather than for the purpose of investigating any particular device, were 
conducted at this station with the results as hereinafter stated. 
PLAN OF THE EXPERIMENT 
The eggs used for this experiment were produced by hens in pedigree 
breeding pens, use of the trap nest making it possible to watch unusual 
variations in size, specific gravity, and other characters. The following 
data were obtained on each of the eggs used in this experiment: Number 
of the hen laying the egg, weight of the egg to the nearest gram, specific 
gravity, record of fertility, death in shell if this occurred, and weight of 
chick if the egg hatched. On the second group of chicks hatched, data 
were also obtained on the weight of the chicks at 7 days, 21 days, and 
35 days of age. 
The specific gravity of all eggs was obtained by using a device which 
is sold commercially for this purpose. Actual specific gravity values 
were determined for each of the divisions on the graduated standard of 
this device and for the various weights of eggs. Translations were made 
so that our comparisons and groupings are made on a basis of actual 
specific gravity. 
Each of the 958 eggs used in this experiment was given a distinct 
number, and all chicks hatched were pedigreed separately. All eggs 
were hatched in the same kind of incubators, the same operator being 
responsible for all hatches. The chicks were brooded indoors for the 
first week and were then moved to a colony house heated with a coal- 
burning brooder stove. 
RELATION OF SPECIFIC GRAVITY TO EVIDENT FERTILITY 
The summary of our data as obtained from a study of 958 eggs indicates 
that there is no correlation between the specific gravity of the egg and 
evident fertility during incubation. Table I consists of a summary of 
these data. 
1 Accepted for publication Feb. 15, 19*2. 
Journal of Agricultural Research, 
Washington, D. C. 
acy 
Vol. XXfll, No. 9 
Mar. 3. 1923 
Key No. Nebr.-s 
(717) 
