The differences in nutritional requirements between Chinook and 

 blueback salnon do not appear to be as great as vras indicated in produc- 

 tion feeding. The failure of the standard meat-viscera mixture to 

 maintain Chinook salmon in actual production operations without an 

 anemia developing in at least a portion of the stock may have been due 

 to several causes: (1) The spring and suiraner races of Chinook may have 

 been inadequately separated with a resultant retention of the spring 

 stock past their normal migration period; (2) some unrecognized variation 

 in hatchery techniques or unfavorable environmental condition may have 

 been active; or (3) an inherent physiological defect within certain of 

 the fish in a lot may have been present causing a malfunction of the 

 hematopoietic system and subsequent anemia. The latter hypothesis seems 

 to have the most general substantiation in fact^ although in certain 

 instances the other factors may have been responsible for the anemia. 



Summary of Results 



Under the conditions of these experiments using blueback and chinook 

 salmon as the test animals, the following conclusions were reached: 



1. Beef lung was an adequate substitute for hog spleen in the 

 standard meat-viscera mixture. Its binding qualities were as good or 

 better than spleen, and its grovjth potential appeared to be equal in 

 this combination. Y/hen combined v/ith hog liver, salmon viscera, and 

 salmon viscera meal, it produced a diet equal in every respect to stand- 

 ard meat -vise era -meal combination. In addition to its compatability in 

 combination diets, the low initial costs of beef lung makes it a valuable 

 addition in production diets, 



2. Whale liver proved unsatisfactory when fed at the 100 percent 

 level. The mortality v/hich resulted from feeding this diet was indi- 

 cated to be caused by a hypervitarainosis A, When substituted for beef 

 liver in the meat-viscera-meal mixture, whale liver proved adequate. 

 The growth response was comparable and no anemia developed. Because of 

 the danger of the development of a hypervitarainosis A and the variability 

 in the vitamin A content of different livers, whale liver should be used 

 with caution. Its use in production diets is not recommended, 



3. Arrow-toothed halibut proved an adequate substitute for hog 

 spleen in the meat-viscera-meal mixture. The growth rate was comparable 

 but the bound quality of the diet was impaired. At the 100 percent 

 level its grov/th potential was inferior to herring. Other combinations, 

 including arrow-toothed halibut, must be tested before it can be recom- 

 mended for production use. 



h' Herring substituted for spleen in the meat-viscera-meal combina- 

 tion resulted in a significant acceleration in the grov/th rate of the 

 fish when compared with the standard combination diet. Here, again, the 

 bound quality of the diet was impaired. l/Jhen used at the 100 percent 

 level, fish which were fed herring developed symptoms indicating a thiamin 



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