368 
Journal o f Agricultural Research 
Vo 1. XXIX, No. 8 
raised cockerels and slightly heavier 
than the hen-raised males. At the end 
of the twenty-eighth week, when their 
experiment was concluded, the Minne¬ 
sota cockerels averaged 1,802.38 gm.; 
the hen-hatched and hen-reared cock¬ 
erels from the Kentucky Station aver¬ 
aged 1,748.1 gm.; and the artificially 
hatched and reared averaged 1,594.6 
gm. 
At hatching, the average weight for 
the series of this investigation is 36.59 
gm.; for the Connecticut chicks, 36.70 
gm.; and for the Kentucky series 41.5 
gm. for the hen-hatched and 41.6 gm. 
for the artificially hatched. 
not been kept continually before it. 
When milk and a constant supply of 
mash were supplied, Group 1 began to 
improve. The greater freedom of the 
range was given to this group alone, 
yet it lagged behind the other groups 
and the first egg was laid by this group 
at 189 days, and by Group 3 at 166 
days. Thus Group 3 began laying at 
an age of 23 days younger than Group 1. 
The chart in Figure 2 gives only the first 
21 days of the curve of Figure 1, plotted 
on a larger scale. The formula from 
which this curve was drawn is: F = [0.1 
(Z+1) 1 - 03 -0.104Z — 0.026]453.59, in 
which Y represents the gross body 
Fig. 2.—Average weight in grams of all chicks for the first 21 days. This curve is plotted on a larger scale 
to show the postnatal decrease in body weight 
There is a difference in the growth of 
the chicks in the four groups here dis¬ 
cussed. At the time of removal from 
the incubator their average weights 
were: Group2, 34.47 gm.; Group3,36.29 
gm.; and Group 4, 39.01 gm. Group 1 
was not weighed until the chicks were 
28 days old, and at that time the 
respective weights were: Group 1, 87.8 
gm.; Group 2, 136.1 gm.; Group 3, 
129.3 gm.; and Group 4, 113.4 gm. 
Group 4, it should be remembered, 
was hatched late in the summer, and 
although it was hen-reared, which has 
been shown to be better than artificial 
brooding, this did not compensate for 
the unfavorable weather conditions. 
Group 1, up to this time (28 days) had 
been given no milk, and dry mash had 
weight of the individual chick and X 
represents the age in days. 
The computed weight drops to 33.5 
gm. on the first day, while the observed 
average was 35.2 gm.; so a correction 
of about 1.7 gm. must be made in 
computing the weight of the one-day- 
old chick. The numerical averages for 
the chicks were: Day of hatching, 36.43 
gm.; first day, 35.2 gm.; second day, 
36.24 gm.; third day, 34.5 gm.; fourth 
day, 39.2 gm. 
This curve shows the characteristic 
postnatal decrease in. weight, which is 
found in so many animals and which 
Minot (15, 16) found to persist in the 
chick until “by the fourth or fifth day 
they appear to entirely recover.” It 
will be seen that the average weight of 
