SICK, ANDREWS, and WHITE: REQUIREMENTS FOR SHRIMP CULTURE 



growth above that obtained in the environmental 

 studies, survival was increased from 80 to 90% 

 to 90 to 100% through the information acquired 

 from the above nutritional comparisons. 



Shrimp obtained little if any sustenance from 

 organic or settled detritus since the continuous 

 flow of filtered seawater through the tanks kept 

 the system relatively free of siltation and ex- 

 traneous growth. Furthermore, starved animals 

 were not able to sustain their initial biomass 

 level beyond 2 weeks, and the populations in all 

 three replicate tanks had died after 7 weeks. 

 Cannibalism appeared to be prevalent among 

 starved organisms, and the decline in weight 

 was undoubtedly moderated due to growth of 

 animals preying upon dead shrimp. 



Diets in Group I with casein as the major pro- 

 tein source produced little growth above susten- 

 ance. Diet 1 with an added mineral mix yielded 

 a significantly higher biomass increase above ini- 

 tial weights at the 5% feeding level than either 

 Diets 2 or 3 which lacked the mix. In addition 

 to the mineral mix. Diet 3 lacked sodium gluta- 

 mate, glycine, citric acid, and succinic acid and 

 correspondingly caused a loss in biomass over 

 the 3-month growth period. Although the above 

 results showed Diet 1 to be significantly different 

 (P < 0.05) from the other diets after the first 

 month of study, results are somewhat confounded 

 with initial differences in stocked biomasses and 

 poor response in general. 



These sustenance biomass levels represented 

 far less growth increase than the 72% of control 

 obtained by Kanazawa et al. (1970) and may be 

 due to a lack of cholesterol in our study. Since 

 many crustaceans are not able to synthesize 

 cholesterol (Van Den Oord, 1964; Dall, 1965; 

 Zandee, 1967), including recent evidence for 

 shrimp (Kanazawa et al., 1971) , the lack of this 

 entity undoubtedly was attributed to the poor 

 performance of these diets. 



Shrimp fed on Group II diets averaged a 37 

 to 63% increase in growth. Although results 

 from Diets 5, 6, and 7 were not significantly dif- 

 ferent (P < 0.05), Diet 6, which consisted of a 

 high ratio of shrimp to fish meal and a low level 

 of casein, yielded greatest biomass increases. 

 Total biomass decreased in diets having a de- 

 crease in percentage of shrimp meal. Growth 



from Diet 8, which contained blended shrimp 

 muscle and lower levels of shrimp and fish meal, 

 was statistically less (P < 0.05) than the other 

 three diets. Again, the control group of starved 

 shrimp was not able to sustain its initial weight 

 and declined in biomass after the first 2 weeks. 



Group III, consisting of yeast, casein, and soy 

 protein hydrolysate diets, produced an average 

 biomass increase of 18 to 39% (Table 1). The 

 combination of diets containing casein, soy, and 

 yeast hydrolysates produced significantly better 

 (P < 0.05) growth than individual hydrolysates. 

 Since results from this group were not better 

 than results after 6 weeks from Diet 5 which 

 was similar except it contained only intact pro- 

 tein, these data indicate that hydrolyzed proteins 

 are not utilized more efficiently than intact pro- 

 teins. 



Comparing food supplied at 0, 5, 10, and 15% 

 of total biomass using Diet 6 illustrated that 

 growth was directly proportional to an increase 

 in feeding rate (Group IV), and may reflect 

 the natural feeding habit of the species. While 

 the population of starved animals disappeared 

 after 8 weeks, the treatments fed at 5% of their 

 biomass increased 58% over their initial weight; 

 those fed at 10% of their biomass increased 

 109%; and those fed at 15% biomass gained 

 164%. The above results indicate that penaeids 

 are capable of consuming large amounts of food. 

 This may be a reflection of their natural tendency 

 to continuously graze upon large quantities of 

 benthic material rather than feed periodically 

 as would a strict carnivore. Although pellets 

 used in all experiments were textured to main- 

 tain consistency in solution for 24 hr, some shat- 

 tering may occur as shrimp gnaw at them and 

 thus some food may be lost through flushing, 

 thus decreasing the efficiency of ingestion as 

 feed levels are increased. 



Although growth was directly proportional to 

 an increase in feeding rate, feeding at low levels 

 was still justified in attempting to determine nu- 

 tritional requirements of shrimp. The benthic 

 material normally grazed upon is low in energy 

 content and is often of relatively poor nutritional 

 content. Feeding at lower fed levels but with 

 food of proper nutritional value could conceiv- 

 ably produce growth comparable to higher fed 



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