GRAZING AND FORAGE PRODUCTION ON NATIONAL FORESTS 39 



assumed that protein was assimilated, regardless of the character 

 and action of the digestive ferments; now it is known that protein 

 to be assimilated by the animal must first be converted by the vari- 

 ous ferments into amino acids, of which not less than 18 different 

 kinds have been recognized as occurring in varying proportion in 

 i he proteins of the different forage crops. Any protein compounds 

 assimilated but not utilized, or those taken into the digestive tract 

 in excess of the supply needed to build muscle and to maintain the 

 animal's " machinery " generally, are eliminated either in the form 

 of urea or uric acid or in the feces. A deficiency in the protein con- 

 tent results in the development of an inferior, undersized animal. 



The forage of very young plants, besides being generally more 

 palatable, has an appreciably higher protein content than that of 

 older plants, as is shown in Table 12. On June 24, when the first 

 of the samples anatyzed for protein content were taken in the spruce- 

 fir type at an elevation of 10,000 feet, the forage growth was not 

 more than about five days old. The October 7 samples were taken 

 after a frost and the close of the grazing season. The protein con- 

 tent is remarkably large in the early stages of growth and in these 

 tests declines in amount as the season advances. 



The amount of protein in the young leafage that is digestible, 

 however, may be comparatively low. The greater proportion of 

 nitrogenous substances contained in young herbage may not be trans- 

 formed by the digestive ferments into amino acids, but exists in the 

 amido stage, in which form it is assimilated probably only in part. 

 In the nutrition of the animal the chemical composition of the forage 

 consumed is much less important than the proportion which the ani- 

 mal can digest (#). Even if the food value of young pasturage were 

 equal to that of the older growth, the advantages are clear in permit- 

 ting the vegetation to reach a reasonable developmental stage before 

 it is cropped, for then a much larger quantity of digestible nutri- 

 ents is produced. 



BOOT DEVELOPMENT AND STORAGE OF PLANT FOOD 



Any condition that stunts aerial growth or otherwise interferes 

 with the normal physiological processes of range plants is likely 

 also to restrict development of the underground organs and thereby 

 curtail the storage of plant food essential to growth later on. The 

 results of this phase of the study appear to be quite uniform among 

 bunch grasses and other herbs whose reproduction is not accom- 

 plished asexually, as by rootstocks. The outstanding facts pro- 

 cured are well shown in violet wheat grass (fig. 15). The effects 

 at the end of the first year of treatment by removing the herbage 

 once in a season (at the time of seed maturity), twice in a season 

 (6 weeks and 10 weeks, respectively, after growth had started), and 

 four times in a season (at monthly intervals, the first harvesting 

 being made 2 weeks after growth had started) are shown in the 

 plants labeled 1, 2, and 3, respectively. The plants labeled 1-A, 

 2-A, and 3-A represent the root development of plants whose 

 herbage was harvested one, two, and four times, respectively, as 

 above stated, for three successive seasons. 



Considering first the root development of» plants treated for a 

 single season, it is noteworthy that the underground growth is 



