Comparative study on the utilization of crystalline methionine and methionine hydroxy analogue calcium by Pacific white shrimp (Litopenaeus vannamei Boone)

Abstract

The objective of this study was to compare the supplemental effects of crystalline DL-methionine (DL-Met) and methionine hydroxy analogue calcium (MHA-Ca) on growth performance of Pacific white shrimp. Eight isoproteinic (355.3 ± 2.0 g/kg diet) and isolipidic (70.0 ± 2.2 g/kg diet) diets were prepared as positive diet (20% fish meal), negative diet (15% fish meal) and DL-Met, MHA-Ca-supplemented diets with the supplementation of 0.03%, 0.06%, 0.09% DL-Met and 0.04%, 0.07%, 0.1% MHA-Ca in negative diet respectively. Pacific white shrimp (0.92 ± 0.03 g) were fed one of the eight diets for 49 days. The results showed that dietary DL-Met did not affect weight gain (WG) and feed conversion ratio (FCR) (p > 0.05), but the supplementation of 0.1% MHA-Ca significantly increased WG, protein and lipid retention, and reduced FCR (p < 0.05) when compared to the negative group, and reached the similar levels as the positive control. The total free amino acids (TFAA) in haemolymph of MHA-Ca groups and PC, NC group peaked at the 3rd hr after feeding, but the peaking time of DL-Met groups was advanced to the 2nd hr. Activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in haemolymph of all MHA-Ca groups peaked at the 2nd hr, but DL-Met groups peaked at the 1st hr after feeding. The above results indicated that the supplementation of 0.1% MHA-Ca in a low fish meal diet could improve the growth performance and feed utilization of Pacific white shrimp, but dietary DL-Met did not significantly affect the growth.