Effect of different stock types and dietary protein levels on key enzyme activities of glycolysis‐gluconeogenesis, the pentose phosphate pathway and amino acid metabolism.

Abstract

A feeding trial was conducted to study the effect of dietary protein (DP) levels on the enzyme activities of different stocks of Macrobrachium rosenbergii juveniles, fed two diets prawn type diets either at optimum (ODP, 32%) or sub‐optimum (SDP, 27%) dietary protein. The activity of key enzymes: glycolysis, gluconeogenesis, amino acid catabo‐lism, pentose phosphate pathway, and energy metabolism was examined on different stocks of M. rosenbergii juveniles in various tissues (muscle, hepatopancreas, and gill). Wild juveniles of M. rosenbergii were collected from the west coast of India, Gujarat (G), Maharashtra (M) and from the east coast of India, Andhra Pradesh (A), and raised in cul‐ture ponds of 200 m2 at 1 juvenile m‐2. The experiment was conducted for a period of 60 days. A Visible Implant Elastomer (VIE) Tag was injected into different prawn juveniles’ stocks A, (3.06–3.10 g), M, (0.80–1.01 g) and G (0.90–1.06 g) for the individual identifica‐tion of each class. All the animals were acclimatized for 7 days before being released into the pond. Each of the two diets, the first with 27% SDP, termed the sub‐optimum level (S), and the second 32% DP, termed the optimum level (O), was fed in triplicate ponds. The weight gain of stocked prawn was significantly higher for G stock (3.03 ± 0.18 g) compared to M stock (2.53 ± 0.25 g) and A stock (1.33 ± 0.10 g). In addition weight gain in ODP was significantly higher (3.05 ± 0.22 g) compared to SDP (2.11 ± 0.17 g). Furthermore, both protein level and stock type had a significant (p ≤ 0.05) effect on the survival rate, specific growth rate, and feed conversion ratio of the prawn. A significant interaction was recorded between metabolic enzyme activities and the variation of di‐etary protein levels and differences in M. rosenbergii stocks, in which stock “G” and “M” exhibited healthier enzyme physiological status than stock “A”. The findings presented here may conclude that the enzymes quickly respond to dietary protein manipulations of cultured shrimp. The results can be useful in identifying the optimum stock (genotypes) in a given culture condition and subsequently higher production may be achieved.