the fact that no thiamine deficiency occurred in comparable diets including 

 arrow-toothed halibut. 



The growth potential and compatability of arrow-toothed halibut is indi- 

 cated as excellent from the results of these and previous trials with blue- 

 back salmon. This product is a scrap fish on the Pacific Coast and is 

 reported to be available in quantity at a cost of less than 5 cents a pound. 

 The use of arrow-toothed halibut in the combinations tested can be recommended 

 on a production basis. 



Herring, because of the presence of thiaminase, cannot be recommended 

 as a diet component for blueback salmon. 



RESULTS OF CHINOOK FEEDING TRIALS 



The feeding trials with chinook salmon were limited to diets previously 

 tested on blueback salmon. The diets selected were those which had produced 

 good growth and no evidence of a nutritional deficiency when fed to this 

 species. Essentially the same results were attained with chinook salmon 

 as with bluebacks (table 3) . 



The standard meat-viscera mixture supplemented with salmon-viscera meal 

 during the second 12 weeks of feeding (Diet 1-C) and two variations of this 

 combination were tested. In the first variation, hog spleen was replaced by 

 beef lung (Diet 2-C) . The results of this alteration were similar to those 

 attained in the blueback tests in that the growth rate was reduced by the 

 substitution of beef lung. The cause of this growth differential may be 

 attributed to the higher fat content of the hog spleen in these tests. The 

 second variation in which herring was substituted for spleen (Diet 3-C) 

 substantiated the conclusions drawn from the blueback trials with herring. 

 The herring diet tested on chinook was a duplicate of the 195l test on blue- 

 back. The chinook showed no evidence of a thiamine deficiency, indicating 

 that sufficient thiamine was supplied by the beef liver, hog liver, and vis- 

 cera in this combination to meet requirements, despite the thiaminase present 

 in the herring. The weight gain on this diet was comparable to the control 

 (Diet 1-C) but did not exceed it as was the case in the 195l trials on blue- 

 back. Two factors, the poor feeding consistency of this diet for chinook 

 salmon and the higher fat content of the spleen in the 1952 trials, may 

 account for the difference in growth response between the two species. 



A combination of one third each of beef liver, hog liver, and salmon 

 viscera supplemented with 10 percent meal during the second 12 weeks (Diet 

 k-C) was included in these trials for comparison in the event that a nutri- 

 tional deficiency developed in the standard control (Diet 1-C). No such 

 deficiency was indicated, confirming the conclusions of Burrows et al. 

 (1952) that the differences in nutritional requirements between chinook and 

 blueback salmon were not as great as anticipated. The growth of fish on this 

 diet was not significantly different from that of fish fed the standard control. 



