18 BrXLETIX 1052. U. S. DEPARTMENT OP AGPJCCXTUKE. 
broilers require feeds containing tissue-forming substances. For this 
reason the rations containing the protein concentrates undoubtedly 
proved valuable, a conclusion supported also by the data in Table 3. 
Experiments 17 to 26 in Table 3 were conducted on Leghorn broilers, 
using the ''house run'" 7 of birds in a co mm ercial feeding plant in San 
Francisco. Calif. Each lot comprised more than a thousand birds. 
Rations 17 to 20 produced very good results, particularly those con- 
taining sesame-seed meal and soy-bean meal. Here again the value 
of protein concentrates in rations for broilers is evident. 
With the exception of Xo. 6. all the rations fed the "springs'* 
(Table 4) were made up. for the most part, of corn, low-grade flour, 
standard wheat middlings, oat products,, and other feedstuff's com- 
monly used for poultry fleshing. These rations were uniformly suc- 
cessful. In view of the results secured with ration 6. containing 
peanut meal, which are better than those obtained from the five other 
rations, it would seem that springs also respond readily to a ration 
containing suitable protein concentrates. 
The results obtained in feeding hens differed from those obtained 
in feeding i mm ature birds. The gains made by the hens were small 
and erratic, because of the more variable physical condition in which 
they were received by the packer. A comparison of the results of the 
small-scale experiments on peanut meal, soy-bean meal, and meat 
scrap l Table 5) with those in which the control ration was fed shows 
that the addition of a protein concentrate does not improve the value 
of the control ration for hens. As further indicated by the battery 
experiments (Table 6^. hens under packing-house conditions gain 
about as much on corn meal or cheaper substitutes and buttermilk as 
on more expensive rations containing protein concentrates. 
EFFECT OF LENGTH OF FEEDING PERIOD ON DIFFERENT CLASSES OF BIRDS. 
In deciding the number of days that birds should be fed. the packer 
must consider the rate of growth of the different classes, the desired 
appearance of the dressed product, and the overhead expense of 
holding the birds. He is also influenced to a great extent by the 
market premium offered for certain weights of broilers and roasters. 
In addition, he should take into account the character of the gains 
produced. Broilers, springs, and roasters grow rapidly and may be 
expected to put on muscle and fat tissue during the feeding period, 
whereas hens put on a much larger proportion of fat. Exact infor- 
mation on this question has been obtained in a series of experiments, 
details of the results of which are reported in Tables 7 to 10. inclusive. 
Tables 17, 18, and 19 give a summary of these data. 
