226 
Journal of Agricultural Research 
Vol. XXXI, No. 3 
yearling hens nor pullets is there any significant difference in the 
mean percentage male and female chick weight of egg weight. 
Table III .—Relationship between the mean percentage chick weight of egg weight 
in eggs producing males and the mean percentage chick weight of egg weight in 
eggs producing females, in each of four groups; and the relationship between the 
mean percentage chick weight of egg weight in eggs producing males and females, 
respectively, in each breed 
Group 
Number 
Mean 
percentage 
chick weight 
of egg weight 
in eggs from 
which males 
were hatched 
Number 
Mean 
percentage 
chick weight 
of egg weight 
in eggs from 
which females 
were hatched 
Difference 
Rhode Island Red yearlings. 
66 
66.33±0.19 
49 
65.65±0.21 
0.68=fcO. 28 
Rhode Island Red pullets_ 
59 
66.56± . 25 
54 
65.83db . 22 
. 73± . 33 
Difference_ 
. 23± . 31 
.18db . 30 
Barred Plymouth Rock yearlings._ 
63 
65.16d= . 23 
49 
64. 56± . 27 
. 60± .35 
Barred Plymouth Rock pullets_ 
123 
65.60± . 20 
106 
64.99± . 23 
. 61± . 30 
Difference_ 
. 44dz . 30 
. 43± . 35 
When the mean percentage chick weight of egg weight per sex 
between the yearling hens and pullets is considered, it is seen that in 
no case was there a significant difference. In every case, the mean per¬ 
centage was greater m the case of the pullets than in the case of the 
yearlings. This is accounted for in the fact that the mean weight of 
the pullet eggs was somewhat lower than the mean weight of the 
yearling-hen eggs. The results in Table III tend to show that pullet 
eggs having the same weight as yearling-hen eggs tend to produce 
chicks having as great a mean weight as the chicks from eggs laid by 
yearling hens. In other words, the weight of the chick seems to be 
determined, more or less, by the weight of the egg from which it was 
hatched. The mean weight of the chicks hatched from small eggs, 
whether they be from yearlings or pullets, seems to be reduced ac¬ 
cording to the extent that the small eggs are used in incubation. 
CONCLUSIONS 
There is no significant difference between the weight of yearling- 
hen eggs from which males are hatched and the weight of yearling- 
hen eggs from which females are hatched. 
There is no significant difference between the weight of pullet eggs 
from which males are hatched and the weight of pullet eggs from 
which females are hatched. 
There is no significant difference in the weight of male chicks and 
the weight of female chicks from eggs laid by yearling hens. 
There is no significant difference in the weight of male chicks and 
the weight of female chicks from eggs laid by pullets. 
There is no significant difference in the percentage chick weight 
(in either sex) of egg weight in yearling hens as compared with pullets. 
If pullet eggs have a significantly lower mean weight than yearling- 
hen eggs, the chicks hatched from pullet eggs will also tend to have a 
significantly lower mean weight than the chicks hatched from 
yearling-hen eggs. 
The separation of the sexes of chicks at hatching time on the basis 
of weight is unreliable. 
