10 Bulletin 81 



There is no one function of the carbohydrates and fat which, like the 

 flesh forming function of the protein, can be considered of more consequence 

 than the others ; all are of the utmost importance to the animal economy. 



Let us now consider each of these five functions in more detail. 



1. Carbohydrates and fat serve as the main supply of fuel wherewith 

 to maintain bodily heat. A certain temperature is necessary for the func- 

 tional activities of the animal body. If it falls below or rises above a cer- 

 tain point, death generally ensues. This heat is kept up by the destruction 

 or burning of certain nutrients in the body. If sugar or starch were burned 

 in a stove, they would evolve heat, and would form, among other things, 

 carbonic acid gas. If, instead of being burned, the starch and sugar were 

 eaten, they would be consumed by the vital processes of the animal, the 

 same amount of heat would be formed, and the same chemical compounds 

 would result as in the burning. Combustion would be slower, but the re- 

 sults would be the same. 



2. Carbohydrates and fat are burned not only to keep the body warm 

 but to produce the energy used in muscular motion. The analogy of these 

 nutrients and the muscular system to coal and the locomotive is close. Any 

 decided exertion of the body is accompanied by much increase in the ex- 

 penditure of carbohydrates and fat. The nitrogenous materials suffer but 

 little loss. Of course they are necessary, yet the carbohydrates appear to be 

 most vitally concerned. Fat more than any other one constituent of the 

 body appears to be available for this purpose. It has for this, for the heat 

 producing function, and for fat storage from 2.25 to 2.5 times the value of 

 carbohydrates. 



3. If there be an excess of these nutrients eaten over what is required 

 for the production of heat and force, storage as fatty tissue may take place. 

 Either nutrient may be used for this purpose. 



4. These nutrients, when digested, serve to protect the more costly 

 protein from over-consumption by the vital processes. As has been pointed 

 out hitherto the several functions of the carbohydrates and fat may be per- 

 formed by protein. These secondary functions of protein are held in abey- 

 ance, however, when the carbohydrates and fat are present in proper quan- 

 tities. 



5. The ultimate source of the fat of milk has been in controversy for 

 years. Protein, food-fat and carbohydrates have all been urged as the 

 causal nutrient. While this point is perhaps not fully settled, Jordan's ' 

 results go far towards proving that carbohydrates are mainly concerned 

 in the formation of milk-fat, since, in his experiment a cow was fed 

 for three months on a ration containing less than 6 pounds of digestible fat, 



i. N. Y. (State) Sta. Bui. 132 (1S98). 



