3io 
Journal of Agricultural Research 
Vol. XXI, No. 5 
III. RELATION BETWEEN THE AMOUNT OF CHEMICAL CONSTITU¬ 
ENTS CONSUMED DURING THE FEEDING TRIALS AND THE 
AMOUNT STORED 
THE PROBLEM 
A pig’s value for meat production depends upon the amount of ma¬ 
terial stored in the body in relation to the amount of feed consumed. 
The problem may be stated as follows: A pig consumes during a feeding 
trial a certain amount of ash, fat, and protein. The problem is to 
calculate the relation between these two sets of quantities and state 
the results in common units, which are in this case pounds. The com¬ 
position of each pig at the beginning of a given trial was assumed to be 
the same as that of a control pig slaughtered when the trial started. 
The amount of ash, protein, and fat in each pig at the beginning of the 
trial was calculated by multiplying the figures for the composition of 
the control pig into the weights of the different pigs used in the trial. 
At the end of each trial the most representative pig in a lot was slaugh¬ 
tered. On the basis of the chemical composition and the weight of the 
emptied body, the pounds of ash, protein, and fat in each slaughtered 
pig were calculated. The differences between the pounds of protein, 
ash, and fat present in each pig at the beginning of the trial and the 
amounts at the end of the trial represent the amount stored. 
The amount and composition of each feed consumed by the pigs 
during the entire trial were carefully determined. From the figures on 
total amounts consumed and chemical composition, a calculation was 
made of the pounds of ash, protein, carbohydrates, and fat consumed 
by each pig during the trial. 
The detailed figures on the amount of the different chemical con¬ 
stituents from the several feeds consumed by the different pigs during 
the feeding trials are given in Table I. Table III gives the figures for 
composition and empty weights of the control pigs and the represen¬ 
tative pig slaughtered at the end of each trial. 
PROTEIN STORED IN RELATION TO PROTEIN CONSUMED 
Protein stored in the body can come only from the digestible protein 
in the feed. Not all the protein digested from the feed can be stored; 
a part must be used for maintenance. The digestible protein in the 
feed must be equal to the amount of protein needed for maintenance 
and the amount that is stored, plus such amounts as are in forms which 
can not be used for these two purposes. The amount of protein that 
can be used for storage and maintenance is limited. If more is fed 
than is needed for these two purposes it may be used for the production 
of heat and energy, or fat. A protein is made up of a number of amino 
acids. These acids must be present in the feed in the proportion re¬ 
quired by the needs of the body. The amount of protein that can be 
