Feeding strategy with alternate fasting and refeeding: effects on farmed pacu production

Abstract

A 36-day trial was conducted to determine the effects of repetitive periods of food restriction and refeeding on growth and energy metabolism in pacu (Piaractus mesopotamicus). A total 264 juvenile fish (36.9±2.8 g) were fed with the experimental diet for 36 days using three regimes: (i) feeding daily to satiation (FD); (ii) no feed for 3 days, then feeding the same amount offered to the control groups for the next 3 days (NF/R controlled); and (iii) no feed for 3 days, then feeding to apparent satiation for the next 3 days (NF/R at satiation). The treatments were distributed into four tanks each. WG and SGR were higher in FD group. Fish refed showed hyperphagia just up to the second day of refeeding. The worst feed conversion rate and the lowest protein efficiency ratio were found in fish NF/R controlled. The lowest values of visceral fat somatic index were found in both fasted fish groups, particularly in NF/R at satiation. The LL and glycogen concentrations, and the hepatosomatic index were all elevated in both feed restricted fish. Muscle lipid showed a tendency to decrease after the cycle of fasting and refeeding. Plasma free fatty acids and glucose levels were elevated in fish subjected to feeding restrictions while serum triglycerides levels were reduced. Triiodothyronine levels were significantly depressed in fish from the NF/R-controlled group and remained at the same levels as the control fish in fish NF/R at satiation. Results indicated that fish subjected to cyclic periods of 3-day satiation or controlled feeding after 3-days of fasting were unable to achieve the final body weight of fish fed to satiation after 36 days.

Feeding rate for pacu reared in net cages

“…However, they differed from those observed by Takahashi et al (2011) (HIS from 1.8 to 2.2% and VSFI from 2.0 to 3.0%), probably because fish were subjected to alternate feeding restriction and feedback loops.…”

“…This species is of great importance to aquaculture, for it presents quick growth, rusticity to handling, easy adaptation to artificial feeding and great acceptance by the consumer market (Urbinati & Gonçalves, 2005). Its adaptability to the system of net-cage rearing was proven by Signor et al (2010), who studied the relation between protein and energy and by Bittencourt et al (2010), who verified the best stocking density for the pacu reared in net cages.…”

Energy deficit does not affect immune responses of experimentally infected pacu (Piaractus mesopotamicus)

“…This is particularly important considering that food restriction is a feeding strategy widely used in the fish farming industry to promote compensatory growth [13], and the benefits of food restriction as promoter of compensatory growth of pacu and consequent reduction of costs in its production have been reported [17,18].…”

“…In this study, we investigated the effects of energetic deficit following starvation on innate immune and metabolic responses of pacu, an important farmed fish in South America, after experimental pathogen exposure. Published studies have concerned pacu response to starvation [17,18], stress [19], metabolism [20] and immune responses [21] but none associated metabolic mobilization to an experimental bacterial infection.…”

Physiological Response to Dolops carvalhoi (Crustacea: Branchiura) Infection by Pacu, Piaractus mesopotamicus, Subjected to Short Cycles of Food Restriction and Refeeding

“…Additionally, previous studies have shown that P . mesopotamicus demonstrate growth compensation and mobilization of energy stores to overcome both short‐term (Takahashi et al ) and prolonged (Souza et al ) fasting periods without any apparent damage to fish health. In this study, therefore, cycles of food restriction and refeeding were evaluated to determine whether they affected physiological responses, such as blood cortisol, glucose and chloride levels, and hematological parameters, of P .…”