Two diets using 5>0 percent salmon viscera supplemented with either 

 50 percent hog liver (Diet 5-C) or 25 percent each of hog liver and beef 

 lung (Diet 6-C) were also tested. Both diets were supplemented with salmon- 

 viscera meal during the second 12 weeks of feeding. Although these diets 

 had a feeding consistency comparable to that of the blueback diets fed the 

 previous year, the activity of the chinook during feeding caused a much 

 greater loss of food particles in the water. As a result the gain in weight 

 of chinook fed these diets was significantly less than those fed the standard 

 meat-viscera-meal mixture (Diet 1-C) . 



The voracious feeding activity of the chinook and their inability to 

 utilize, or their disinterest in, the smaller food particles resulting from 

 this activity, is believed to be the cause for the difference in growth 

 rates attained between the two species of fish. Another possibility is that 

 an actual difference in amino-acid requirements exists between the two species. 

 The obvious food wastage, rather than differences in the protein requirements 

 of the species, appears to be responsible for the differences in diet utili- 

 zation. 



Certain of the diets produced mortalities higher than that of the stan- 

 dard control. While the differences in mortality were statistically signifi- 

 cant, the greatest loss of fish did not exceed 5 percent for the 2lj-week 

 period. Since no deficiency symptoms were apparent and the mortalities were 

 comparatively low, it i s not believed that these differences were great enough 

 to preclude the use of any of these diets for production use on the basis of 

 mortality alone. 



The results of these feeding trials indicate that chinook salmon can be 

 maintained for a 2h-week period without beef liver in the diet. Hog liver 

 or hog liver and beef lung in combination with salmon viscera appear to meet 

 the vitamin requirements of chinook salmon. The growth potential of all the 

 diets tested may be considered good. On the basis of cost per pound of fish 

 produced, the diets containing 50 percent salmon viscera and either hog liver 

 or hog liver and beef lung in combination are superior to any of the others. 

 The inclusion of herring in chinook production diets is not recommended on 

 the basis of the results of the blueback trials. The probable presence of 

 thiaminase in herring makes its use dangerous in production operations. 



SUMMARY OF RESULTS— BLUEBACK SALMON 



The results of the 1952 trials utilizing fingerling blueback 

 salmon as the test animal are summarized as follows: 



1. During a 12-week period in cold water the addition of 10 percent 

 salmon meal to a meat-viscera mixture significantly increased mortality 



