the caloric intake of the fish from 2,000 in diet 

 20 to 2,350 in diet 21 significantly increased fat 

 deposition but did not increase protein utilization 

 or deposition. The protein calorie to energy 

 calorie ratio was lower than the ratios in the 

 20- and 25 -percent protein diets as would be 

 expected since the protein intake was increased. 

 The optimum level at this time appeared to be 

 1:0.8. 



24 weeks. --Results at the 20-percent 



level of protein intake showed that diet 8 with 

 2,000 calories produced fish with significantly 

 greater fat deposition than did diet 7 with 1,650 

 calories and diet 6 with 1,300 calories. There 

 was no difference between fish from diets 7 and 

 6 in fat deposition. Raising the caloric level 

 from 1,300 in diet 6 to 1,650 calories in diet 7 

 resulted in a significant increase in the amount 

 of protein deposited in the fish. The additional 

 increase to 2,000 calories in diet 8 did not in- 

 crease protein deposited over that of the 1,650- 

 calorie diet. A caloric intake of 1,650 calories 

 per kilogram with a protein calorie to energy 

 calorie ratio of 1:1 appears to be optimum as 

 it did at 12 weeks. Increasing the caloric 

 level from 1,650 calories in diets 10 and 15 to 

 2,350 calories in diets 12 and 17 increased fat 

 and protein deposition with the protein utiliza- 

 tion factor remaining the same . Tne increase to 



2,350 calories also produced significantly 

 greater protein deposition than did comparable 

 diets at caloric intakes of 2 , 000 . A protein 

 calorie to energy calorie ratio of 1:1.35, with a 

 caloric intake level of 2,350, appears to be 

 superior to the 1:1 ratio favored at 12 weeks. 

 Results at the 27. 5 -percent protein level were 

 similar to those of the 25-percent level. The 

 caloric increase to 2,350 in diet 21 produced 

 significant increases in fat and protein depo- 

 sition as compared with diet 20 at 2,000 calories. 

 Whereas the 1:0.8 protein calorie to energy 

 calorie ratio and a caloric intake at 2,000 

 appeared to be optimum at 12 weeks, a 1:1 ratio 

 with a caloric intake level of 2,350 calories 

 appears to be more favorable at 24 weeks, when 

 feeding at a level of 27.5 percent protein. 



Proximate analysis of samples of fish 

 from the diets showed a reduction in the percent- 

 age of body fat in the fish at the end of 24 weeks 

 as compared with analysis at the end of 12 weeks , 



while the percent protein in the body of the fish 

 remained approximately the same. These 

 changes in body composition indicate an increas- 

 ed energy requirement in the larger fish. 



By increasing the caloric level of a diet, a 

 sparing action was produced on the protein and 

 vitamin requirements of the fish at aU three 

 levels of protein intake. Phillips et al. (1963), 

 in diet trials with brook trout, also reported a 

 sparing action on the protein utilization of brook 

 trout, when corn oil was added to the diet. This 

 sparing action is also in agreement with the 

 results of Combs et al. (1962). At the 20-per- 

 cent protein intake levels, a point appears to 

 have been reached where further additions of 

 calories as an energy source becomes inpracti- 

 cal. A protein calorie to energy calorie ratio 

 of 1:1 was optimum at both 12 and 24 weeks. 

 However, there was a trend towards greater 

 protein deposition, as the ratio was increased 

 to 1:1.5 in diet 8. The presence and extent of 

 the hypovitaminosis may have been a factor 

 which limited protein deposition at this protein 

 level. At both the 25- and 27.5-percent protein 

 levels, the protein calorie to energy calorie 

 relation changed as the fish became older and 

 larger, indicating an increased energy require- 

 ment. The increased protein deposition and 

 utilization in the fish receiving these caloric 

 increases supports this conclusion. 



Stamina tests 



The summarized results in table 2 show 

 that the performance indices of the diet fish 

 varied considerably. Normally, a difference in 

 performance of three is considered to be sig- 

 nificant. This wide spread can be explained by 

 the extreme differences found within the diets 

 themselves. Not all of the fish within a diet 

 suffered the nutritional deficiency to the same 

 degree; consequently, performance within the 

 same diet was somewhat variable. Even though 

 differences were not significant the fish in diets 

 in which the vitamin deficiences were marginal 

 had higher stamina indices than the fish in diets 

 where the deficiency was extensive . 



10 



