Effect of feed additives in the diet on the growth and testicular development of male red claw crayfish (Cherax quadricarinatus) using orthogonal experiments

Abstract

Vitamin E (VE), nucleotides (NT), Haematococcus pluvialis (H.P), Arachidonic acid (ARA), and yeast extract (YE) play important roles in the growth and reproduction of aquatic animals. Where, the objectives of this study were: 1) to determine what factors might have more significant effects on the growth and testicular development of MRC-crayfish; 2) to obtain an optimum level of each tested factor, and 3) to determine the best combination of the five tested factors to be used as an improved technology to upgrade the traditional MRC-crayfish culture. The orthogonal array design of OA16 (45) was used to evaluate the effects of five factors with four levels for each factor, (namely, A (VE) 40, 160, 240 and 320 mg/kg; B (NT) 2, 4, 6 and 8 g/kg; C (H.P) 2, 4, 6 and 8 g/kg; D (ARA) 5, 10, 15 and 20 g/kg; E (YE) 2.5, 5, 10 and 15 g/kg) on crayfish for 102 days trial. A total of 612 crayfish (initial weight ranged between 38 and 49 g) were randomly distributed into seventeen treatment groups with three replicates of 12 crayfish. The results showed: 1) VE and ARA at the tested levels had even more influences on the weight gain and feed conversion ratio of the MRC-crayfish than NT, H.P, and YE; 2) All Factors had significant effects on the survival rates of MRC-crayfish (p < 0.05); 3) NT and ARA at the tested levels had even more influences on the testicular development of the MRC-crayfish than VE, H.P, and YE. In contrast, it had no significant effects on the hepatosomatic index of MRC-crayfish. 4) the five factors at the tested levels had no significant effects on the hepatosomatic index of MRC-crayfish (p˃0.05); 5) The best combination for the five factors with the optimal levels was A3B4C2D1E3, which could not only improve the growth of MRC-crayfish, but also the testicular development, where the optimal formula composition for MRC-crayfish culture was a combination of VE 240 mg/kg, NT 8 g/kg, H.P 4 g/kg, ARA 5 g/kg, and YE 10 g/kg.