CONDREY, GOSSELIXK, and BENNETT: SHRIMP DIETS 



ity Nose demonstrated, a U'p of about 80 ^r com- 

 pared to our observed value of 92 '^f. Thus his 

 low values for protein assimilation on plant diets 

 may have been a function of the low nitrogen 

 analysis of the food rather than an inherent in- 

 ability of shrimp to digest plant proteins effi- 

 ciently. 



Feeding Efficiency 



Feeding efficiency (grams assimilated per 

 gram dry weight of particulate material in- 

 gested) is presented in Figure 1 and Table 5. 

 As is demonstrated by the figure, the magnitude 

 of the assimilation efficiency of an organic moi- 

 ety itself may be misleading, as its nutritive val- 



ue depends not only on digestibility but also on 

 its concentration in the food. For instance, in 

 the diatom diet the lipids were assimilated with 

 an efficiency of 99^;, but the feeding efficiency 

 was only 19 "^r (when expressed as milligrams 

 per milligram of food X 100). Furthermore, 

 although in this diet the lipid fraction was the 

 most readily assimilated, twice as much protein 

 as lipid was assimilated per unit dry weight in- 

 gested. Also although the digestibility of AF-1 

 carbohydrates was the lowest of the four diets 

 (f^'cH,o = 49 rf), feeding efficiency for carbo- 

 hydrates was higher than from either the detri- 

 tus or the diatom because of the high carbohy- 

 drate concentration in AF-1. For the defined 

 diets feeding efficiency parallels U' because of 

 their high and comparable ash-free dry weights. 



Table 5. — Feeding efficiency — the assimilation of total 

 organic weight, protein, lipid, and carbohydrate per mil- 

 ligram dry weight of diet ingested. 



Diet 



Diatom 

 Detritus 

 AF-1 

 Chow 



Total 



organic wt 



A 



740 

 680 

 450 

 710 



Proteins 



440 

 240 

 210 

 390 



Lipids 



US 

 190 

 170 

 56 

 35 



Corbohydrates 



34 

 70 

 97 



190 



Minimum Rates of Net Assimilation 



In tests with C. fusiformis and Trout Chow 

 diets, fecal pellets were recovered quantitatively 

 over 36- and 12-hr feeding periods, respectively. 

 Because a small but undetermined amount of 

 fecal material was lost, the fecal release rates 

 reported for these diets are minimal. As is 

 shown in Table 6, defecation of shrimp when fed 



INGESTED 



DIATOM 



^50.. 



DE TRITU S 



BR 



m: 



ASSIMILATED 



SHRIMP 



740 



z: 



450 



,™™7aQ„ 



EGESTED 



^ 



I«.J^ 



70. 



mH Ash 

 j 'i j Protein 



Carbohydrates 

 Lipids 



LJn accounted 

 Total organics 



Figure 1. — Organic budget of 

 shrimp fed on defined diets. 



1287 



