Using scope-for-growth estimates to compare the suitability of feeds used in shrimp aquaculture
The scope-for-growth (SFG) of an animal is the portion of assimilated energy used for secondary production after maintenance requirements are met. The SFG of Penaeus setiferus was calculated as the difference between absorption (A), and the sum of the respiration (R) and excretion (U) [SFG = A - (R+U)]. Protocols were developed and SFG determinations were replicated 18 times for shrimp maintained on an experimental feed (diet I), and 18 times for shrimp maintained on a commercial feed (diet II). Somatic growth of the shrimp was determined by direct weight measurements and by conversions of SFG results into wet weight and the two values were compared. Results yielded a SFG of 99.8 +/- 16.03 J/g per d and 33.78 +/- 7.64 J/g per d for diets I and II, respectively. Scope-for-growth estimates appear to be suitable for comparisons of effects of various culture conditions on shrimp.