Jan. 2, 1920 



Meat Scraps versus Soybean Proteins 



397 



The table may be summarized as follows : 



Lot No. 



Ration. 



Average 

 total feces 

 nitrogen. 



Increase 

 in waste. 



13 



1,5,9- 

 2, 6, 10 



3,7,11 

 4, 8, 12 



Basal 



Basal +5 parts protein. 

 Basal+io parts protein 

 Basal -j- 1 5 parts protein 

 Basal 4-20 parts protein 



Per cent. 

 2. 24 

 2.79 



3-57 

 3-95 

 4-59 



Per cent. 



24-5 



59-4 



76.3 



105.0 



The nitrogen soluble in N/jo hydrochloric acid was considered to be 

 ammonia, urea, and amino acid nitrogen. The nitrogen insoluble in 

 N/jo hydrochloric acid was considered to be uric acid and residual 

 nitrogen. 



The data in Table III indicate that in all lots receiving 5 parts of 

 protein in addition to the basal ration, the excreta contained an average 

 of 2.79 per cent nitrogen; in lots receiving 10 parts protein, they contained 

 an average of 3.57 per cent; in lots receiving 15 parts, they contained an 

 average of 3.95 per cent; in lots receiving 20 parts protein, they contained 

 an average of 4.59 per cent; whereas in the lot receiving the basal ration 

 only, they contained an average of 2.24 per cent nitrogen. This last 

 figure was taken as maintenance nitrogen excretion. Since the feces 

 in lots receiving 5 parts protein in addition to maintenance contained 

 2.79 per cent nitrogen, it was computed that the waste in excretion 

 was 24.5 per cent greater than when the basal ration alone was fed. 

 In the same manner 59.4 per cent more feces nitrogen was obtained for 

 lots receiving 10 parts protein, 76.3 pey cent more for lots receiving 15 

 parts, and 105 per cent more for lots receiving 20 parts. In brief, the 

 greatest gain in weight was made with the least necessary nitrogen loss 

 in feces when the basal ration was supplemented with 10 parts of protein. 



It will be noted in Table III that the ash content of the feces collected 

 when chicks were 4 weeks old and growth was most rapid was much 

 greater for all lots than that of the samples collected when the chicks 

 were 20 weeks old and growth was less rapid and maintenance require- 

 ments were greater. The excretion of nitrogen was very constant for 

 all lots receiving the same amount of protein; and since the protein 

 consumed increased by 5 parts in four successive rations, the average 

 increases over control lot 13 were 2.79, 3.57, 3.95, and 4.59 per cent, 

 respectively, for each addition of 5 parts of protein to the basal ration. 

 Thus it would appear that there was no economy in nitrogen excretion at 

 the point where the gain was most efficient (the addition of 10 parts 

 protein), though such an economy might have been expected. Table III 

 also shows that a 2-gm. sample of feces of any nitrogen content con- 

 tained nearly the same weight of N/io acid-soluble nitrogen (ammonia, 



