and substitution of the fish produced the greatest growt-h resonse. For 

 this reason both arrow-toothed halibut and herring were substituted 

 for spleen in different diets o The substitution of arrow-toothed hali- 

 but (Diet 27) resulted in a marked acceleration in the growth rate of 

 the fish significantly more than those fed the hog spleen (Diet 23), 

 No nutritional deficiencies were apparent iji this diet.. Because of the 

 deletion of spleen the bound quality of the diet was greatly impaired 

 and leaching of the water soluble components of the diet was obvious. 

 Some alteration in this diet is indicated to improve its feeding con- 

 sistency. The growth response of the fish fed the herring ration (Diet 

 28) was slightly but not significantly greater than that of those fed 

 arrow- toothed halibut. It will be recalled that the growth rate of the 

 fish which were fed herring as the entire ration (Diet 22) was signifi- 

 cantly higher than that of those fed arrow-toothed halibut (Diet 21). 

 The trend indicated in the composite diets and the significant difference 

 displayed in the single component st^dii's leads to the conclusion that. 

 ^^--^r-ing has a higher growth potential than does halibut- In the compos r 

 ite ^^3t the possible thiamin deficiency tn the herring wa^ adequately 

 covered by the other components o It is entirely possible that the 

 thiamin content of herring is not low, but that the thiamin deficiency 

 induced in experimental fish fed herring was the result of a thiaminase 

 enzyme which destroys the thiamin present. The feeding consistency of 

 Diet 28 was inferior to that of the meat-viscera -meal mixture. To make 

 good production diets, either of these rations should be altered to 

 include a more adequate binding agent. 



In this group of diets the beef liver, hog liver j beef lung, salmon 

 viscera, and meal combination appears to be the most adequate substitute 

 for the standard meat-vis cera^neal combination o The substitution of 

 either herring or arrow-toothed halibut for spleen offers excellent • 

 possibilities providing that these diets are handled and fed very care- 

 fully to prevent excessive leaching. In actual production operations, 

 it is doubtful if these diets would prove adequate until the feeding 

 consistency is improved by the addition of more adequate binding agents. 

 Whale liver, because of its high vitamin A cOTitent and the danger of 

 the creation of a hyper vitaminos is in the fish, is not recommended as a 

 diet component. The low-temperature-dried whale meal is an adequate 

 substitute for vacuum-dried salmon viscera meal. Should this product 

 become available commercially, its use in production diets could be 

 recommended. 



The third group of diets in the second experiment was designed to 

 develop a low cost ration for salmon for use during warm-water periods. 

 In these diets salmon viscera, I4.5 percent, and salmon viscera meal, 

 10 percent, were used as the base. Hog liver (Diet 29), beef lung 

 (Diet 30), tuna liver (Diet 31) j, and equal parts of hog liver and beef 

 liing (Diet 32) were used as supplements to this base. 



The hog liver plus salmon viscera diet fed in the first experiment 

 (Diet 6) was supplemented with 10 percent of salmon meal to form Diet 29 



15 



