12 PRINCIPLES OF FEEDING FARM ANIMALS 



Crude Protein in Feedingstuffs. — In the ordinary analysis 

 of feedingstuffs, the proteins and the non-proteins are not 

 determined separately, but they are determined together 

 as crude protein. The chemical determination of crude 

 protein is based upon the fact already noted, that proteins 

 contain an average of 16 per cent of nitrogen. Thus to 

 determine the amount of crude protein in a feedingstuff, 

 the amount of total nitrogen in a weighed sample is found 

 and then multiplied by 6.25 to obtain the amount of crude 

 protein in the sample. (If 16 per cent of the weight of 

 protein consists of nitrogen, to find the weight of the total 

 protein, one multiplies the weight of the nitrogen by the 

 number of times 16 per cent is contained in 100 per cent, 

 or by 6.25.) The calculated weight of the crude protein, 

 divided by the weight of the sample and multiplied by 100, 

 gives the percentage of crude protein in the sample. 



Crude protein usually is the most expensive nutrient to 

 buy or produce and the one most often lacking in farm 

 rations, especially in the corn-belt, where corn is the prin- 

 cipal crop. Table 3 shows the average percentages of crude 

 protein in the different classes of ordinary feedingstuffs. 

 The packinghouse by-products, as dried blood, tankage, 

 and meat scraps, contain the largest amounts of crude 

 protein, — 24 to 84 per cent. Then follow in approximately 

 the order named, the various oil by-products, — 18 to 45 

 per cent ; leguminous seeds, — 20 to 36 per cent ; the oil- 

 bearing seeds, — 16 to 23 per cent ; the cereal by-products, 

 — 10 to 31 per cent ; and the legume hays, — 13 to 19 per 

 cent. The cereal grains are only medium in protein con- 

 tent, — 9 to 12 per cent. The non-leguminous hays, straws, 

 fodder, stover, fresh grasses, silage, and roots contain the 



