510 STATE BOARD OF AGRICULTURE. 



INVESTIGATION REGARDING SUCCULENCE. 



F. W. ROBISON. 



[Special Bulletin No. 32.] 



IXTKODUCTION. 



From time to time during the last thirty years a number of experiment stations 

 have compiled data from experiments bearing on the subject of animal nutrition. 

 These have largely taken the form of digestion experiments dealing with various 

 feeds peculiar to a particular locality or relating to the more common American 

 feed stuffs. Practically, the sole aim of such experiments has been to determine 

 the per cent of digestible protein, etc., in the various feeds, and, as a result, 

 feeders and stockmen throughout the country have learned to look to the digestible 

 dry matter of a feed instead of the total amount of nutrients in the feed when 

 comparing its merits. It has long been known that the domestic animals were 

 unable to utilize completely any of the common feed stuffs, and it has been con- 

 sidered very appaj'ent that the value of a feed to an animal depends not only 

 upon the quality and amount of food consumed, but also upon the amount excreted 

 in the feces and not utilized by the animal's system. Consequently data bearing 

 on the digestibility of the various feeds available have been welcomed by feeders 

 throughout the world and there is now at their disposal the digestive coefiBcients 

 of nearly all the common feeds. 



"With the beginning of the investigations on the maintenance ration for steers 

 by Keilner and other European investigators, and in this country by Armsby and 

 others, a suspicion has been creeping gradually into the minds of more advanced 

 feeders and scientists that the story as told by the digestion experiments was 

 incomplete, and with the further progress of respiration experiments on man and 

 animals this suspicion has been more or less confirmed. 



Much discrepancy has arisen from the too rigid application of the balanced 

 ration, and while its great importance is still undisputed there are factors that 

 enter in to modify and in some instances to counteract its effect. To make more 

 specific, two rations are compounded having the same nutritive ratio, or, in other 

 words, constituting rations in which the relations between the proteids, carbo- 

 hydrates and fats are identical. It is found on actual trial that these two 

 rations are not equal in value, not because they are not equally digestible, but 

 because some factors other than nutritive ratio and digestibility have entered 

 in to modify the effect in question. 



The ultimate object of the consuviption of food is the production of energy. 



In giving feed to a horse it is desired to convert the inert material into energy 

 which manifests itself in some form of motion. In giving feed to the dairy 

 cow it is likewise desired to convert the same into energj' which manifests itself 

 in preserving the mechanism of the animal's body and in providing human food, 

 which latter is finally converted into the energy of maintenance and of motion 

 in the human body. It is readily conceded that movement of any kind is a 

 manifestation of energy in the animal's tody and can be traced to but one source, 

 and that, evidently, the food consumed. 



All processes in the body then require the expenditure of energy, the beating 

 of the heart, movement of the blood, phenomena of digestion, of absorption and 

 of excretion; movement of the food in the alimentary canal, mastication or chew- 

 ing of the food, etc., all require the expenditure of energy, and research has shown 

 also that it is no inconsiderable amount of energy thus expended. It is clear 

 that if the chewing and digestion of food require the expenditure of energy, the 

 form and preparation of the food must make some difference in the gross amount 

 of energy expended by the animal. Quite recent experiments have shown that 



