EXPERIMENT STATION BULLETINS. 223 



having also a chemical composition very similar to that of the dry lean 

 muscle of lean meat and called casein. Now the class of substances in- 

 cluding diy lean meat, the albumen of the white of eggs, the casein of 

 cheese is called ji^'otein. The chemist finds that this protein, derived 

 from our usual cattle feeds, contains not far from 16 pounds of nitrogen 

 per hundred weight, or, in other words, has 16% nitrogen. If, then, we 

 remember that 16 multiplied by 6.25 makes a hundred we can see that 

 it is possible to determine how much protein there is in a given material 

 by multiplying its content of nitrogen by 6.25. 



All of our cattle foods contain compounds having a composition sim- 

 ilar to that of dry lean meat, the albumen of eggs and the casein of 

 cheese and serving, for our domestic animals, the same purpose that 

 the protein of meat, cheese and eggs does for human beings. It must 

 not be understood that meat, eggs and cheese are the only articles of 

 human diet that furnish protein. The truth is far otherwise. While 

 meat has a larger proportion of protein than have most vegetables, the 

 latter are by no means wanting in this food constituent. Even potatoes, 

 a very starchy food, contain, when boiled, 2.7%* of protein. Beans have 

 a much larger per cent, on the average 21.81 pounds of protein to the 

 hundred weight. White bread shows fully 9.5% of protein. The lim- 

 ited number of experiments that have been tried on this point lead us 

 to believe that a pound of protein derived from potatoes is equally as 

 valuable as the same amount derived from the lean meat. This point 

 has not been well established. Much will depend upon the digestibility 

 of the protein in the two forms. 



Turning now to cattle foods we find that some of them may be sup- 

 posed to be related to the appetite of the animal in much the same way 

 that eggs, cheese and meat are to the appetite of men. To this class 

 would belong such feeding stuffs as cotton seed meal, linseed meal, 

 gluten meal and buckwheat middlings. Cotton seed meal is richer in 

 protein than cheese. It contains 42% of protein while cheese has but 

 28.2%. Linseed meal usually has 32% of protein while eggs have but 

 13%. 



Protein is known by other names. Because it contains nitrogen, it 

 is called nitrof/cnous substance. Because the protein compounds re- 

 semble the white of an egg they are called alhiiminoids. 



Fat. The meaning of the word fat in relation to cattle feeding is 

 the same as when used in ordinary conversation. The fat found by the 

 chemist in corn meal, clover hay and other feeding stuffs is very similar 

 in composition and in physical properties to the animal fat, lard, but- 

 ter or tallow. The quantity of fat in the various feeding stuffs differs 

 widely. Of the total weight of the seeds of flax and the cotton plant, 

 fully one-quarter is oil, while straw and green fodder have relatively 

 very little. The fact that nearly all of our fodders contain some fat is 

 the one that it is important to remember. 



Carbohydrates. Both protein and fat are essential constituents of the 

 diet of animals and men, but these two factors together do not con- 

 stitute a complete daily ration. The appetite calls for some starchy 

 food. In the case of men this is usually supplied by potatoes or by 



*The sign % signifies, of course, per cent. 



