CARE OF CAPTIVE ANIMALS — WALKER 319 



eating it. It may appear that they are not hungry, when in reality 

 they are, but lack confidence in the food. For this reason, new food 

 should be left long enough for them to become accustomed to it. 

 Such unfamiliar food will sometimes be taken only after it has been 

 repeatedly offered to an animal. If it is possible to make a gradual 

 change in the diet where such change becomes necessary, it is prefer- 

 able gradually to reduce the food that the animals have been receiv- 

 ing, supplementing with the food that they are expected to consume 

 in the future. In the course of any such change, it is important that 

 the animal be offered as wide a variety of foods as possible, in order 

 that it may make a selection. It is frequently found that animals 

 eat and relish foods that experienced so-called animal authorities 

 say they will not eat. 



Protein, carbohydrate, and fat should form parts of every diet, 

 since these are always present to some degree in every animal cell. 



In general, carnivores have a higher protein requirement than 

 herbivores and omnivores. Therefore, lean meat or so'me other pal- 

 atable food of high protein content should constitute the major por- 

 tion of their diet. Carbohydrates and fat can be utilized by these 

 animals, but neither should replace the meat entirely because of the 

 essential amino-acids and vitamins contained therein. Carbohydrates 

 and fat can be used to supplement exclusively protein diets, though 

 the former nutrient is of limited value to most carnivores. Red meat 

 or muscle is not the sole source of protein. Tendons, connective tis- 

 sue, cartilage, bone, brain, and nerves, as well as the viscera, are 

 excellent sources of protein that are frequently wasted. 



Herbivorous animals are able to digest large amounts of roughage. 

 The latter should be of good quality in order to insure adequate pro- 

 tein, minerals, and vitamins. Small amounts of grain are commonly 

 used as a supplement to the roughage. 



Omnivorous animals stand somewhere between the carnivorous and 

 herbivorous species as to requirements. Apparently they can utilize 

 more carbohydrates than carnivores, and less roughage than 

 herbivores. 



Presumably most of the known vitamins required by man are neces- 

 sary to most lower animals as well, but perhaps not in the same 

 proportions. It is likely that furred and feathered creatures may 

 require certain vitamins in greater proportions than mankind, at least 

 during the seasons for growing hair and feathers. 



The vitamins ^ known at this time, and a brief summary of infor- 

 mation regarding them, are given below. Since vitamin studies have 

 been made primarily of foods used by human beings, and evidences 



• Most of the information regarding vitamins has been condensed from the Physicians' 

 Vitamin Reference Book issued by the E. R. Squibb Co. and the Nutritional Charts issued 

 by the A. J. Heinz Co. 



