Compensatory growth and digestive enzyme activity of Litopenaeus vannamei submitted to feeding restriction in a biofloc system

Abstract

Feeding restriction is a strategy in shrimp farming management that may promote compensatory growth after feeding is re‐established. This study aims to evaluate the effects of two feeding restriction regimens on the compensatory growth and digestive enzymes activity of Litopenaeus vannamei reared in biofloc system. Juvenile shrimp (0.46 ± 0.18 g) were stocked (320 individuals/m3) in 310 L tanks. The experiment comprised two phases: (a) Feeding Restriction (30 days) when shrimp were submitted to three feeding regimes, Control (fed daily), R1F1 (repetitively fasted one day and fed one day) and R2F1 (repetitively fasted 2 days and fed 1 day); and (b) Refeeding (28 days) when shrimp were fed daily. In the restriction phase, shrimp growth and digestive enzyme activities were reduced in R2F1 and R1F1. However, during the refeeding phase, enzyme activities and feed conversion improve significantly in R2F1 and R1F1. Control group attained higher final weight, but its final biomass was similar to R1F1. Litopenaeus vannamei exhibited partial compensatory growth, probably due to improved feed conversion efficiency driven by increased enzyme activity. It is possible to reduce feeding by 50% (R1F1) in biofloc systems for 28 days, without compromising the biomass produced at the end of a 30‐day refeeding period.

Compensatory growth: Fitness cost in farmed fish and crustaceans

“…34 In contrast, in the same crustacean species, cycles with refeeding times equal to or less than the deprivation period over durations of 30, 40 and 56 days only led to partial compensation. 53,54,85 On the contrary, in other studies, application of continuous dietary restriction led to partial compensatory growth; however, refeed fish and crustaceans still exhibited a significantly higher SGR than control organisms at the end of the refeeding period. 65,79,80,86 Sustained high growth rate at the end of the experiment may suggest that a longer refeeding time could have resulted in a higher degree of compensatory growth.…”

“…To determine the capacity of the CG response according to the employed feed restriction protocol, it is recommended to evaluate the SGR for specific periods. 53,54 If biometrics cannot be conducted consistently, the determination of compensation coefficients could facilitate the determination of CG. [55][56][57] Compensation coefficient greater than 1 indicates compensatory growth, and it is calculated as follows:…”

“…13,28 Indeed, in some studies, compensatory response could not be demonstrated in fish and crustaceans previously exposed to moderate dietary restriction, whereas stricter/ longer restrictions showed clear compensation. 43,54,63,69 Won and…”

“…33 This mechanism is achieved by an improvement of digestive and absorptive capacities, especially due to the increasing activity of digestive enzymes when food is reintroduced. 34,54,[69][70][71][72] Fish and crustaceans can reflect hyperphagia very rapidly upon the return of food availability, 43,44,52,61,73,74 as in Labeo rohita fish, which, after 1, 2 or 3 weeks of fasting, showed a significantly higher food intake than continuously fed fish. 61 During food restriction, organisms rely on their energy reserves to maintain their metabolic rate, depletion triggers ghrelin production in fish that promotes feed intake 24,75 and allow for immediate hyperphagia upon return of feed (see Section 3).…”

“…84,106,114 On the contrary, if restriction and refeeding periods are adapted, regeneration of digestive tissues and reactivation of enzymatic activities can be observed allowing compensatory growth. 54,79 Overcompensation of the size/mass of digestive tissues, such as the pyloric caeca 69,116,142 and digestive enzyme activity, 139,148 has been reported. For example, Atlantic cod (G. morhua) subjected to 68 days of fasting showed a 29-fold increase in digestive capacity over 28 days of refeeding via an increase in pyloric caeca size and tyrosine activity.…”