Dietary methionine requirement of juvenilePseudobagrus ussuriensis

Abstract

An 8-week feeding trial was conducted to determine the optimum dietary methionine (Met) requirement of juvenile Pseudobagrus ussuriensis with an initial average weight of 0.60 g reared in indoor flow-through and aerated aquaria. Six isonitrogenous (430 g kg À1 protein) and isolipidic (50 g kg À1 lipid) test diets were formulated to contain graded levels of crystalline L-methionine (4.9, 9.0, 11.8, 14.2, 18.1 and 20.8 g kg À1 dry diets, respectively) at a constant dietary cystine level of 2.5 g kg À1 dry diets. Equal amino acid nitrogen was maintained by replacing methionine with nonessential amino acid mixture. Fish were randomly allotted to 18 aquaria (1.0 9 0.5 9 0.8 m) with 50 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. No significant difference was observed in survival of fish (84.67-91.33%). Specific growth rate (SGR), weight gain (WG), feed conversion ratio (FCR), protein productive value (PPV) and protein efficiency ratio (PER) were significantly affected by different dietary methionine levels (P < 0.05). WG, SGR PPV and PER increased, while FCR decreased with increasing dietary methionine level from 4.9 to 11.8 g kg À1 (P < 0.05). However, with further increase from 11.8 to 20.8 g kg À1 , WG, SGR PPV and PER significantly decreased, FCR increased (P < 0.05). The whole body and muscle composition were affected by different dietary methionine levels (P < 0.05). Condition factor (CF) increased with increasing dietary methionine levels up to 11.8 g kg À1 (P < 0.05) and after 11.8 g kg À1 methionine diet, but not significant, declines were observed (P > 0.05). Hepatosomatic index (HSI) of the 4.9, 9.0, 11.8 and 14.2 g kg À1 Met diets was significantly higher than that of fish fed diets 18.1 and 20.8 g kg À1 Met diets (P < 0.05). Viscerosomatic index (VSI) of the 4.9, 9.0 and 11.8 g kg À1 Met diets was significantly higher than that of fish fed diets 14.2, 18.1 and 20.8 g kg À1 Met diets (P < 0.05). Quadratic regression analysis of WG and PER against dietary methionine levels indicated that the optimal dietary methionine requirement for maximum growth and feed utilization of juvenile Pseudobagrus ussuriensis was 14.3 and 14.1 g kg À1 dry diet (35.3 and 34.8 g kg À1 dietary protein), respectively, in the presence of 2.5 g kg À1 dry diets cystine.

Evaluation of Filamentous Fungal Biomass Cultivated on Vinasse as an Alternative Nutrient Source of Fish Feed: Protein, Lipid, and Mineral Composition

“…On the other hand, dispensable amino acids (DAA) are those that can be synthesized in the animal's body [45]. Amino acids are involved in many cellular processes, such as the synthesis and degradation of proteins, the urea cycle, energy metabolism, synthesis and metabolism of lipids, and glucose and cell signaling [51].…”

“…However, this mechanism is not clear in fish, and proline is categorized as conditionally EAA. Methionine is usually the first limiting amino acid in many fish diets, especially when the fish diet contains a high proportion of plant protein sources, such as soybean meal and crop meal [51].…”

Optimum level of dietary monocalcium phosphate determined based on optimal growth and vertebrae phosphate content of juvenile Ussuri catfish,Pseudobagrus ussuriensis

“…However, there are no commercially available feeds specifically formulated for Ussuri catfish limiting its development for aquaculture. In a previous study, we reported that 445.1 g/kg protein with lipid at 50 g/kg (P/E ratio of 29.06 mg protein/kJ) seemed to meet the need for optimal growth and feed utilization (Wang et al., ), and the research on dietary methionine requirement and replacing fish meal by soybean meal in the diets of Ussuri catfish has been also evaluated (Wang, Yu, et al., 2016; Wang, Che, et al., 2016). However, the dietary mineral requirements have not been reported for this species.…”