SHAPE AND WEIGHT OF EGGS IN RELATION TO THEIR 
HATCHING QUALITY 1 
By M. A. Jull, Poultry Husbandman, and S. Haynes, Chief Scientific Assistant, 
Animal Husbandry Division, Bureau of Animal Industry, United States De¬ 
partment of Agriculture 
INTRODUCTION 
During recent years the annual replenishment of the chicken 
flocks of the country by means of artificial incubation has been ac¬ 
companied by excessive embryonic mortality. The problem of the 
hatchability of hen eggs is therefore an important one, inasmuch as 
there are a number of factors that may cause the death of a relatively 
large number of embryos in proportion to the total number of fertile 
eggs artificially incubated. Concerning the various factors possibly 
contributing toward this heavy embryonic mortality, the reader is 
referred to a resume contributed by Dunn. 2 There is need for much 
more investigational work concerning the effects of the various proc¬ 
esses of incubation on embryonic development and variations in 
respect to the inherent hatching quality of eggs. 
Concerning the inherent qualities that possibly affect hatchability 
Dunn has investigated the relationship between the weight and the 
hatching quality of White Leghorn eggs. Among other things, 
he found that for both pullets and hens, the largest eggs did not 
hatch as well as eggs near the average weight for the flock, and that 
there was no correlation between the mean weight of the eggs laid by 
an individual pullet or hen and the proportion of her fertile eggs 
which hatched. If the first result obtained by Dunn applies to other 
breeds and varieties of chickens as well as to other strains of White - 
Leghorns, then it becomes important to determine to what extent 
large eggs should be eliminated from the eggs saved for incubation. 
On the other hand, the second result noted by Dunn implies that 
the elimination of the eggs laid by individual birds whose mean egg 
weight is above the mean for the flock will not affect the proportion 
of fertile eggs hatching. This apparent paradoxical situation is ex¬ 
plained by the fact that Dunn also found that among the eggs of an 
individual fowl those which were above the mean weight for the 
individual did not hatch as well as those which were below the mean 
weight, regardless of the absolute mean egg weight. 
In order to ascertain the relationship between weight and hatching 
quality of eggs in Barred Plymouth Rocks and Rhode Island Reds, 
the writers have gone over the incubation records of a large number 
of birds, including pullets and hens, and have prepared the data as 
presented in the following tables. The relationship between shape 
1 Received for publication January 19,1920; issued December, 1925. 
2 Dunn, L. C. the relationship between the weight and the hatching quality of eggs. 
Conn. Storrs Agr. Exp. Sta. Bui. 109: 92-114. 1922. 
Journal of Agricultural Research, Vol. XXXI, No. 7 
Washington, D. C. Oct. 1,1925 
Key No. A-101 
( 685 ) 
