Influence of food attractants (methionine, lysine and alanine) on sturgeon larvae and fingerlings nutrition

The objective of this study was to determine the influence of food attractants (methionine, lysine and alanine) on growth performance and survival rates of Acipenser percicus larvae and fingerlings during the acclimation period to the formulated diets. A total of 3300 Acipenser percicus larvae and 1500 Acipenser percicus fingerlings with the initial mean weights of 0.4±0.09 (mean±SD) and 1.8±0.3 (mean±SD) g, respectively were randomly distributed into 30 aerated plastic tanks of 30 L capacity for larval stage and 50 L capacity for fingerling stage provided with a water flow rate of 0.2 litre per second. This study was conducted at the International Sturgeon Research Institute for two periods of 62 and 70 days over two years. Nine iso-caloric diets were formulated to contain 0, 1 and 3 % of three amino acids methionine, lysine and alanine. In addition, a diet containing 50 % of plant protein supplemented with 3 % of methionine, lysine and alanine was also formulated to compare the effects of plant-protein-based diet with the experimental diets so as to prepare a cost-effective practical diet for this species. Fish were fed each of the ten experimental diets and a completely randomized design in a 3×3 factorial arrangement was used for the experiment. At the end of the feeding trial, final weight (7.5 ± 0.3 g) in Persian sturgeon larvae fed M3L1A3 diet (3% methionine and alanine and 1% lysine) was significantly higher than those of fish fed the other experimental diets (p≤0.05) and then M1L1A3 diet (1% methionine and lysine and 3% alanine) was significantly better (p≤0.05) than other experimental diets. There were no significant differences (p≥0.05) in final weights among M1L1A1, M3L1A1, M3L3A1, M1L3A3 and M3L3A3 diets, while theses diets showed significant differences in final weight with fish fed plant-protein-based diet (3.2±1 g) and without amino acids supplemented diet (M0L0A0) (3.6± 0.4 g). Based on final weigh obtained from Persian sturgeon fingerlings, there were significant differences (p≤0.05) between M3L3A3 (3% methionine, 3% lysine and 3% alanine) (11.1±3.6g) and M3L1A3 (3% methionine, 1% lysine and 3% alanine) (10.4±3.1g) diets with M1L1A1, M1L3A1, M1L1A3, M0L0A0 and plant-protein-based diets. Results of final weigh in fingerling stage also indicated that there were no significant differences (p≥0.05) among M1L1A1 (7±1.2 g), M3L1A1 (8.6±1.6 g), M1L3A1 (7±0.5 g) and M1L1A3 diets (6.6±1.0 g) with M0L0A0 (5.8±1.8 g) and plant-protein-based diets. Analysis of total length in Persian sturgeon fingerlings indicated that there were no significant differences (p≥0.05) among treatments. The highest total length (12±1.6 cm) was recorded in fish fed M3L1A3 diet. Results obtained from this study revealed that young growing Persian sturgeon has greater requirements for methionine in diet, while lysine and alanine at the levels of 1 and 3% for Persian sturgeon fingerlings and at the level of 3% for larvae stage show the same effects on growth performance. Hence, it may be concluded that the dietary alanine and lysine requirements for sturgeon larvae during the acclimation period to formulated diet is estimated to be more than 1 %. No significant differences were observed in survival rates in sturgeon larvae and fingerlings among treatments