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    • Article

      Lysine and arginine requirements of juvenile Asian sea bass (Lates calcarifer) 

      DP Murillo-Gurrea, RM Coloso, IG Borlongan & AE Serrano Jr. - Journal of Applied Ichthyology, 2001 - Blackwell Publishing
      Two separate experiments were conducted to determine the dietary requirements of juvenile Asian sea bass Lates calcarifer Bloch for lysine and arginine. Fish (average initial weight: lysine experiment, 13.12 ± 0.12 g; arginine experiment, 2.56 ± 0.13 g) were given amino acid test diets for 12 weeks containing fish meal, zein, squid meal, and crystalline amino acids. Each set of isonitrogenous and isocaloric test diets contained graded levels of L-lysine or L-arginine. The feeding rate in the lysine experiment was at 4–2.5% of the body weight day−1, while in the arginine experiment it was at 10–4% of the body weight day−1. The fish (20 per tank, lysine experiment; 15 per tank, arginine experiment) were reared in 500-L fibreglass tanks with continuous flowthrough sea water at 27 °C and salinity of 31 ppt in the lysine experiment and at 29 °C and salinity of 29 ppt in the arginine experiment. The experiments were in a completely randomized design with two replicates per treatment. Survival was high in fish given adequate lysine or arginine. Mean percentage weight gains were significantly different in fish fed varying levels of lysine or arginine. Fish fed high levels of L-arginine suffered high mortalities. No significant differences were obtained in the feed efficiency ratios (FER, g gain g−1 feed) of fish fed graded lysine, although the values tended to increase as the dietary lysine level was increased up to the requirement level. In contrast, in the arginine experiment, significant differences in FER of fish among treatments were obtained; the highest FER was observed in fish fed the diet containing an optimum arginine level. On the basis of the growth response, survival, and FER, the lysine and arginine requirements of juvenile Asian sea bass were estimated to be 20.6 g kg−1 dry diet (4.5% protein) and 18.2 g kg−1 dry diet (3.8% protein), respectively. These data will be useful in the further refinement of practical diet formulations for the Asian sea bass.
    • Article

      Sulphur amino acid requirement of juvenile Asian sea bass Lates calcarifer 

      RM Coloso, DP Murillo-Gurrea, IG Borlongan & MR Catacutan - Journal of Applied Ichthyology, 1999 - John Wiley and Sons
      The dietary requirement of juvenile Asian sea bass Lates calcarifer for total sulphur amino acids was studied. Fish (average initial weight of 2.59 plus or minus 0.08 g) were reared in twelve 500 L fibreglass tanks provided with flow-through seawater at 26 degree C and salinity of 31 ppt for 12 weeks. They were fed semipurified test diets containing 6.2, 7.2, 8.1, 9.0, 10.8, or 12.6 g methionine/kg dry diet and a basal level of 3.1 g cystine/kg dry diet. The mean crude protein of the diets (containing defatted Peruvian fishmeal, squid meal, soybean meal, and free amino acid mixture to simulate the pattern of hydrolysed sea bass protein) was 46.02 %. The crude fat content of the diets was 10.51 % from a 1:1 mixture of cod liver oil and soybean oil. Survival was 100 % in all treatments. On the basis of the growth response, the total sulphur amino acid requirement of juvenile Asian sea bass was estimated to be 13.4 g/kg dry diet (2.9 % of protein). Fish fed low levels of L-methionine had significantly lower weight gains and feed efficiency ratios as well as slightly higher hepatosomatic indices. No nutritional deficiency signs were observed other than growth depression in fish fed on diets that were low in methionine. This information is valuable in further refinement of formulations of practical diets for the Asian sea bass.