580 NUTRITION OF FARM ANIMALS 



nitrogenous matter is chiefly in the form of true proteins of 

 recognized nutritive value, their carbohydrates are largely 

 starch, and their ether extract chiefly true fat. Being closely 

 related to the nutrition of the young plant, the composition of 

 the properly matured seed shows much smaller variations than 

 that of the coarse fodders. The degree of maturity of the 

 seed, however, materially affects its composition and in much 

 the same way as it does that of the coarse fodders. In the 

 early stages of seed formation, the protein and ash flow abun- 

 dantly from the vegetative organs to the seed, while later the 

 ripening of the seed is largely an accumulation of carbohydrates. 

 Any influences, therefore, which check the normal development 

 of the seed, such as drought or lodging of the grain, tend to 

 produce a seed richer in protein and poorer in carbohydrates. 

 Light, shriveled grain, therefore, tends to be high in protein. 

 Moreover, the ingredients of unripe seeds differ to a consider- 

 able extent from those of ripe seeds. The nitrogen, for ex- 

 ample, is to a larger extent in the form of non-protein rather 

 than true protein, and the carbohydrates are in the form of sugars 

 of one sort or another rather than starch, as in the ripe grain. 

 688. Composition and digestibility of cereals. The cereal 

 grains are characterized by a medium percentage of protein 

 (8 to 14 per cent), chiefly composed of true protein, a rather 

 low percentage of fat (1.5 to 6 per cent) and a high percentage 

 of carbohydrates, largely starch. Their ash is small in amount 

 and in it potassium and phosphorus acid are prominent, while 

 but little calcium is found. Maize contains rather less protein 

 than the other cereal grains, with correspondingly high percent- 

 ages of starch and of fat. While it has been shown that the 

 protein content of corn can be notably increased by selection and 

 breeding, the effects of the latter have not yet sensibly affected 

 the character of the commercial crop. The naked grains (maize, 

 rye, wheat) show a comparatively high percentage digestibility, 

 and both in this respect and as regards their composition ex- 

 hibit less variation than the hulled grains (oats, barley). In 

 the latter, the variable proportion of the relatively valueless 

 hulls to the kernel causes both composition and digestibility to 

 vary greatly. Oats, for example, have shown the extremes of 

 6 and 17 per cent protein and 3 to 7 per cent of fat. The hulls 

 resemble straw in composition and value. They therefore in- 



