Table 5. — Effect of protein level on the protein 

 deposition and utilization 



to be higher than for comparable diets at the 

 25-percent level, indicating the possibility 

 that the optimum efficiency level has been 

 reached or slightly exceeded. 



Effect of caloric 1 evels 



Peanut oil was added to seven diets in 

 order to determine the effect of increased 

 caloric intake on protein deposition, protein 

 utilization, and fat deposition. Fish in diets 

 6,7, and 8 were fed at a meat-meal ratio of 

 10:90 with caloric levels of 1,300, 1,650, and 

 2,000 calories per kilogram, respectively, 

 and the protein intake was stabilized at 20 

 percent. At the 25-percent protein level, fish 

 in diets 10, 11, and 12 were fed at a meat-meal 

 ratio of 30:70, and their respective caloric in- 

 takes were 1,650, 2,000, and 2,350. The 

 10:90 meat -meal ratio in the 2 5 -percent pro ■ 

 tein diets was also tested with fish in diets 15, 

 16, and 17 having caloric intakes of 1,650, 

 2,000, and 2,350. At the 27.5-percent pro- 

 tein level, fish in diet 20 were fed at a caloric 

 intake of 2,000 calories per kilogram of food, 

 while the caloric intake of fish in diet 21 was 

 increased to 2,350 calories per kilogram. The 

 results of this section are presented in table 6 . 



Protein deposition and utilization, 12 weeks. 

 --At the 20-percent protein level, fish fed 

 diet 7, at a caloric intake of 1,650 calories 

 per kilogram of diet, had significantly greater 

 protein deposition and utilization than did fish 

 fed diet 6, at a caloric intake of 1,300 calories 

 per kilogram of food. An additional increase 



to 2,000 calories, in diet 8, produced results 

 no better than those of the 1,650-calorie diet. 

 These results confirm those of Combs et al. 

 (1962). Essentially the same results were 

 found at the 25 -percent protein level in the 

 30:70 meat-meal diets with fish from the 2,000- 

 calorie ration, diet 11, and the 2 ,350-calorie 

 ration, diet 12, having significantly greater 

 protein deposition than fish from the 1,650- 

 calorie ration, diet 10, but with no difference in 

 protein utilization. The increase to 2,350 

 calories in diet 12 produced no significant in- 

 crease in protein deposition when compared 

 with diet 11, with 2,000 calories per kilogram. 

 The 2,350-calorie ration, diet 17, in the 10:90 

 meat -meal ratio was the only diet in which the 

 fish had a significant increase in protein depo- 

 sition due to caloric increase. An increase in 

 the caloric intake of fish in the 27. 5 -percent 

 protein diets did not alter protein deposition 

 or utilization. 



24 weeks . --The analysis of the 20-per- 



cent protein diets at 12 weeks revealed that a 

 significant increase in protein deposition and 

 utilization occurred when the caloric intake of 

 the fish was increased from 1,300 to 1,650 

 calories per kilogram, but increasing the caloric 

 intake to 2,000 did not increase protein deposition 

 or utilization above that of the 1,650-calorie diet. 

 Results were the same at 24 weeks, with fish 

 from diet 8 at 2,000 calories and diet 7 at 1,650 

 calories having significantly higher protein de- 

 position than fish from the comparable diet 6 at 

 1,300 calories. There was no difference between 

 fish in diets 8 and 7. At the 25-percent protein 



