Describing growth and predicting feed intake in the marine prawn Fenneropenaeus indicus : Part I: Theoretical and practical aspects of measuring and predicting genetic parameters

Monitoring and predicting growth and feed intake of cultured aquatic animals is a significant problem in aquaculture. The present study examines the potential of an approach based on potential accretion rate of body protein to predict live weight gain and feed requirement of the marine prawn, Fenneropenaeus indicus. The protein accretion rate was predicted using the Gompertz equation while the growth of body components and nutrient gains therein was established using allometric relationships. Live weight gain was determined by summing the accretion rates of body protein, lipid, water, ash and carbohydrate. The model parameters included the protein content at maturity (Pd m , [mg]), the rate of maturing (β, [/d]), the maximum rate of protein deposition (Pd max , [mg day⁻¹]), the lipid to protein ratio at maturity (LPR m , [Ld m :Pd m ]), ash (APR m ,[Ad m :Pd m ]), water (WAPR m ,[WAd m :Pd m ]) and carbohydrate to protein ratio at maturity (CPR m ,[Cd m :Pd m ]), and the exoskeleton to flesh ratio (E:F). To generate information to establish these parameters, feeding trials with prawn were carried out in indoor tanks and an outdoor growout pond. Juveniles from the same brood stock were allowed to grow to adults under conditions assumed ideal. Tank reared animals failed to obtain similar growth to those cultured in the pond. Values for the above parameters for a mixed batch of pond reared prawns were estimated to be 6541 mg, 0.014/d, 32.68 mg day⁻¹, 0.03, 0.20, 3.30, 0.06 and 1:3.6, respectively when reared at 19-27 °C and 21-27[per thousand]. Results indicated that the model proposed here, derived from and based on research in higher vertebrates, was well suited to describing the genotype of F. indicus reared under semi-intensive conditions. This study is, to our knowledge, the first to examine and describe mathematically the rates of body lipid, ash, water and carbohydrate accretion in prawns as a function of protein gains in the flesh and exoskeleton of F. indicus.