Effect of fasting on compensatory growth and digestive enzymatic activity of freshwater prawn post larvae (Macrobrachium rosenbergii) during its culture in biofloc

During 75 days, the fasting/cyclic refeeding effect was evaluated on survival, growth, and digestive enzymatic activity in the hepatopancreas of freshwater prawn post larvae (PL 20) cultured in a system with/without biofloc. A completely randomized experimental design was used in triplicate to compare: (B3) three-day feeding and three-day fasting; (B6) three-day fasting and six-day refeeding; both cultures in biofloc; (C3) three-day fasting and three-day refeeding; and (C6) three-day fasting and six-day refeeding, both in clear water and two controls with daily feeding were included: (B) culture in biofloc and (C) culture in clear water. The physicochemical variables in water were within the tolerance range for PL’s growth. The survival in all treatments was high (>80%) and similar. The most efficient growth was obtained in prawns in B treatments, which was significantly higher than the C treatments, while the growth of the prawns in C treatment was similar to B3 and B6, suggesting that the biofloc covered the nutritional requirements that allowed compensatory growth despite the temporary absence of feed. Higher values of enzymatic activities were observed in the hepatopancreas of prawns in all B treatments, except for acid protease which was similar for all. Prawns in B treatments showed the highest activity of the alkaline protease, in contrast, fewer values were observed in prawns from C3. This study confirmed compensatory growth with the application of biofloc technology in the culture of freshwater prawns in short fasting periods and beneficial effects on growth performance, digestive enzyme activity, and prawn health.