Procedure 



Blneljack salmon ( Oncorhynchas nerka) were selected as the experimental 

 animal. All fish used on the experiments were from a single age group with 

 a conrparahle history. Distribution into troughs was made with the Leaven- 

 worth sampler to insure random sampling. 



Survival ejqoeriment 



This phase of the experiment consisted of 4 diets: 100 percent heef 

 liver, 100 percent acetone-extracted salmon viscera meal, 100 percent low- 

 temperature- dried salmon viscera meal, and 90 percent frozen salmon viscera- 

 10 percent apple pomace. For the first 3 diets, quarter troughs were stocked 

 at 250 grams or 179 fish each, with 2 troughs on each diet. The fish were 

 fed all they would eat which was in excess of the amount usually required 

 for this species. The 90 percent frozen salmon viscera-10 percent apple 

 pomace diet was also included in the growth evaluation studies. Consequently, 

 it was tested on a full trough containing 1,000 grams or 715 fish. This 

 groUT) was fed on the "basi-s of the ratio of the amount of food to the total 

 weight of fish as required by this species. 



The eroeriment was initiated on July 9. On September 30 the group 

 which was being fed the frozen salmon viscera diet showed no evidence of 

 anemia and only 1 fish (O.l percent) had died. This was a lower mortality 

 rate than that of the beef liver control group. Thus it can be said that 

 for the 12-week experimental period the salmon viscera diet was at least 

 the equivalent of the iJeef liver diet. 



On July 27, the fish fed the 100 percent acetone-extracted aaloen 

 viscera meal showed evidence of a nutritional deficiency. The symptoms 

 obseirved indicated that there was a thiamine deficiency. On July 28, this 

 diet was altered to include 0,8 grams of thiamine hydrochloride per 1,000 

 grams of fish weight — approximately 4 times the amount required to produce 

 maximum storage in trout. To bind the vitamin into the diet, 10 percent 

 gel&tin plus water were added. The first week after the syn^jtoms were 

 noted and the diet changed, the mortality amounted to 70 percent of the 

 stock, for the next 2-week period the loss was 65 percent of the remaining 

 fish on hand. For the next 2-week period the loss was 31 percent of the 

 stock. The total mortality of the lot for the entire experiment 



was 93 "oercent. The symptoms of a thiamine deficiency gradually disappeared 

 but anemia was apparent when the experiment was concluded on September J. 



The fish fed 100 percent low-temperature-dried salmon viscera meal 

 exhibited the same symptoms of a thiamine deficiency on August S? after 31 

 days on the experimental diet as contrasted with 19 days for the fish fed 

 the acetone-extracted meal. On August 8, the diet was altered as in the 

 preceding instance to include thiamine and gelatin in the same proportions. 

 In the next 10 days following the diet change the loss amounted to 5^ 

 •oercent of the fish on hand. For the next two weeks the mortality was 58 

 percent of the remaining fish. In all, 8I percent of the initial number 



53 



