MEATS AS TROUT FOOD 145 



Since boef liver is too expensive to feed to large fingerlings and 

 'older fish we must look elsewhere for a suitable meat. On the whole 

 pi<>- liver appears to be superior to either sheep liver or sheep plucks, 

 especially for brook trout. Not only has it made a better showing 

 llian either of the sheep products when fed straight, but the sticky 

 (■(insistency of ground liver makes it an ideal binding medium for use 

 with dry meals. Although fresh fish of the coarser and cheaper 

 grades have been fed at hatcheries to some extent the results have not 

 been entirely satisfactory. It usually requires twice as much fish as 

 meat to produce an equal growth, and the trout themselves are often 

 mot as healthy as those on diets of meat. Furthermore, fish is difficult 

 to keep fresh and the feeding of decayed fish has in some cases killed 

 trout outright. Our experiments indicated the general unsuitability 

 of fish, particularly as a food for brook-trout fingerlings, since its use 

 was always accompanied by severe losses and inferior growth. It 

 seems, therefore, that the feeding of even cheap fish in any consider- 

 able quantity to fingerlings, at least, is a matter of doubtful economy. 



Our experiments clearly indicate that, with the possible exception 

 of liatcheries which happen to be located near a local supply of very 

 cheap meat, it is advisable in the interest of economy to feed a mix- 

 ture of meat and dry products rather than to keep the fish on a 

 straight meat diet. Since fresh meats contain from TO to To per cent 

 of water, it is evident that at from 5 to 10 cents a pound the dried 

 products are much cheaper than even the cheapest of the fresh meats 

 in common use. It appears inadvisable, however, to attempt the use 

 'of dry products before the fish reach a length of about 2 inches. 

 'Despite the fact that in some instances we have obtained good results 

 in feeding dry products to smaller fish it is probable that in ordinary 

 I hatchery practice it will be better to wait until the fish are large 

 enough to eat the mixture w^ithout its being broken up into fine par- 

 ticles of meat and meal. This necessarily results in considerable 

 waste and not infrequently the meal is not eaten at all. 



Even with 2 and 3 inch fingerlings the dry products which can 

 be fed successfully are very few. First among these is clam meal; 

 but since this product is available only in small quantities it appears 

 that we must rely chiefly on the dried milks to replace part of the 

 meat in the diet of fingerlings. These are the only dry products 

 which, on the basis of our experiments, we can recommend at 

 present, although it is probable that there are others which may 

 prove equally valuable. 



I After the fingerlings reach a length of 4 to 5 inches a considerably 

 1 wider range of dry foods is available. These include vacuum- 

 ' dried fish meals and shrimp meal. These products do not produce 

 as rapid growth as clam meal and the dried milks, but are consider- 

 ably cheaper and can, of course, be purchased in any quantity. 



Although trout can undoubtedly utilize cereals and beans to some 

 extent, when properly cooked, we are not yet convinced that they 

 form a valuable addition to the menu unless they are used in small 

 amounts to serve primarily as binders. We believe that at pres- 

 ent prices fish and shrimp meals are more economical than cereals, 

 since in our experiments they have always given much better results 

 than the latter. 



While our experiments show that several dry meals can be success- 

 fully incorporated in trout rations it is also evident that some fresh 



