Recovery growth of Cherax quadricarinatus juveniles fed on two high-protein diets: Effect of daily feeding following a cyclic feeding period on growth, biochemical composition and activity of digestive enzymes

Abstract

Abstract Recovery growth of C. quadricarinatus juveniles was evaluated during a daily feeding period that followed a cyclic feeding period, by the analysis of the biochemical composition and structure of the hepatopancreas, and the activity of digestive enzymes. Two different diets were evaluated: diet A (49% crude protein) and diet B (38% crude protein), and juveniles were subjected to one of the following feeding regimes for each diet: DF, under which they were daily fed throughout the experimental period (120 days); and 4F/4D, under which they were fed for 4 days followed by 4 days of food deprivation in repeated cycles from day 1 to day 45, and daily fed from day 45 to day 120. Juveniles under the 4F/4D regime showed compensatory growth and reached the same body mass of control juveniles (i.e. complete catch-up growth) at the end of the experiment. This physiological response was not affected by the two high-protein diets tested, and it may be at least partly explained by an improved food conversion ratio, a similar ability to digest and absorb nutrients and an increased efficiency in protein digestion with respect to control juveniles. The 4F/4D regime had no negative effects on the nutritional state and health of red claw crayfish, which confirms the high tolerance of the species to food deprivation. The present results are important from an economical point of view since they show that it is possible to significantly reduce the amount of food offered in culture systems, and consequently reduce production costs, without affecting juvenile growth.