Oct. is, 1924 Postnatal Growth of the Single-Comb White Leghorn 
365 
chickens were given the regular “ lay¬ 
ing mash/’ hopper fed. This mash 
consists of the following ingredients: 
6 lbs. corn meal, 4 lbs. ground oats, 
4 lbs. middlings, 2 lbs. bran, 2 lbs. 
alfalfa meal, 7 lbs. beef scraps, 
34 lb- charcoal, 1 per cent common salt, 
3 per cent bone meal. With this 
mash was given the usual allowance of 
grain. Throughout the experiment 
the chickens were fed by the Poultry 
Division, so that they might have the 
usual care and diet. 
Complete autopsies were made on 
100 normal chickens, 50 from Group 
environmental factors, variations in 
different breeds of fowls, etc. 
Weighings. —The chickens in Group 
1 were weighed once a week from June 
26, 1920, to March 4, 1921. The 
other three groups were weighed every 
day from day of hatching, or when 
they were removed from the incubator, 
until the 1st of October; then only 
three times per week until December 3, 
and once per week thereafter, until 
killed and autopsied. The weighings 
were always made in the morning 
before the chickens were fed or allowed 
the freedom of the yard or range. 
Fig. 1.—The two point-to-point curves show the average observed live weight per chicken for all groups 
combined. Up to the 56th day the line represents the average for both sexes; after this time the upper 
line represents the average for the males and the lower line that for the females. The six entries just be¬ 
yond the 300-day line are the six adults (of uncertain age) 
1, 15 from each of Groups 2 and 3, 
and 14 from Group 4. In addition to 
these 94 normal chicks at various 
ages, 6 older normal chickens (adults) 
were likewise autopsied for comparison. 
The number of birds used, is not 
sufficient to establish final conclusions 
on many points; but the results will at 
least indicate the general trend of the 
growth changes which occur in the 
single-comb White Leghorn from time 
of hatching to maturity. These re¬ 
sults will serve as a basis for further 
and more detailed study of various 
phases of the problem, such as the 
variations due to nutrition and other 
They were weighed on a pair of spring 
milk-scales, sensitive to a hundredth 
of a pound. The entire group, or as 
many as possible, were weighed at a 
time, and the average weight per 
chick (in grams) was determined. 
Autopsies— In selecting individuals 
for autopsy those which were most 
nearly in accord with the weights as 
given by Card and Kirkpatrick (2) 
at corresponding ages were selected at 
various periods. This makes the aver¬ 
age weight of the autopsied chickens 
higher than the average live weight 
of the entire lot at the corresponding 
points (fig. 1). 
