PHYSIOLOGICAL STUDIES OF THE RUFFED GROUSE 769 



body substances) exceed anabolic processes (assimilative reaction involving the building up 

 of body substances) in body cells, the maintenance of vital functions is interfered with. On 

 the other hand, anabolic activities equaling or exceeding catabolic activities result in a stable 

 physiological balance of vital processes. Thus when an animal neither loses nor gains 

 weight, the body is in a condition of nutritive equilibrium. The adjustment between the two 

 phases of total metabolism in the body is essential for the continuation and maintenance of 

 life at normal levels. 



Foods are utilized in the body through a process of oxidation or burning in which heat is 

 one of the principal products. Since the basic food ingredients (protein, fats and carbohy- 

 drates) differ in their heat producing values"" and food substances are made up of various 

 combinations of these ingredients, it is necessary to use some standard unit of comparison. The 

 most convenient unit of this kind is the large calorie*. 



Correcting for the part of each substance lost in digestion the physiological fuel values of 

 the basic ingredients are: 



1 gram of carbohydrate 4.0 calories 



1 gram of fat 9.0 calories 



1 gram of protein 4.0 calories 



On this basis, the foods used in this experiment compare as follows: 



1 gram of mash furnished 3.23 calories, or 1 pound, about 1 167 calorics 

 1 gram of grain furnished 2.78 calories, or 1 pound, about 1261 calories 

 1 gram of alfalfa furnished 0.70 calories, or 1 pound, about 317 calories 

 1 gram of ajiple furnished 0.64 calorics, or 1 ixiund. almtit 290 ralnrics 



The total nutritive value of each food substance is not entirely included in its calorific 

 value, for the vitamins, water, and minerals contained therein are not direct sources of heat 

 energy. These last elements^". howc\er. arc vitally beneficial as contributing materials neces- 

 sary for normal piowth. reproduction, hatchabilitv. maintenance of other vital functions, and 

 cure and ])rc\t'titinn of disease. The walei content of the different substances composing the 

 ration ranged from S to 15 per cent for grain and mash, 80 to 85 per cent for apple, and about 

 70 per cent for alfalfa. Neither does the total calorific \alu(' include the addition of one 

 ])int of cod liver oil to each 100 pounds nf grain. 



The nutritional requirements of grouse were studied by measuring the daily food and 

 water consumption of 16 apparently healthy birds, nine for a period of 33 days at an air tem- 

 perature of 65°F. and seven for 13 davs at 8.5° F. Thev were fed a</ libitum on a ration of 

 mash, grain, alfalfa and apple, the calorific values of which are described above. Water was 

 available at all times. The amount of food and water consumed as well as changes in body 

 weight were recorded simultaneously each morning and evening at regular hour? during the 

 periods of study. The results are presented in table 116. 



Of the nine birds held at 65°F.. fi\e (Group A) either maintained or increased their 

 body weight, whereas four (Group B) lost weight on the amount of food eaten. Approach 

 to a normal caloric intake is demonstrated for the birds in Group A. It is improbable, how- 

 ever, that actively feeding grouse would have to produce additional body heat to combat an 

 air temperature of 65°F. Therefore, the caloric value of the ingested food in excess of 

 daily physiological needs permitted a storage of organic substances in the body and the birds 

 gained in weight. On the other hand, the amount of food consumed by Group B birds was 



^^ A laryc calurie is equivalfiit to the aiiKuint i>f liPiil miiiiii-ii tti i;iU<" ItlOO grams of water 1°C. 



