Dietary methionine requirement of juvenile blunt snout bream (Megalobrama amblycephala) at a constant dietary cystine level

Abstract

A 9-week feeding trial was conducted to investigate the dietary methionine requirement of juvenile Megalobrama amblycephala at a constant dietary cystine level. Six semipurified diets were formulated to contain graded dietary methionine levels from 3.9 to 15.4 g kg À1 in about 2.5 g kg À1 increments in the presence of 2.2 g kg À1 cystine. Results showed that specific growth rate (SGR) and protein efficiency ratio (PER) significantly increased with increasing dietary methionine levels from 3.9 to 12.4 g kg À1 and thereafter kept stable. Maximum protein productive value (PPV), nitrogen retention efficiency (NRE) and liver weight were observed in 8.5 g methionine kg À1 diet. Protein contents in whole fish body were positively correlated with dietary methionine level, while lipid contents were negatively correlated with it. Morphological index and hepatic glutamate-pyruvate transaminase (GPT) activities were independent of dietary methionine levels. However, dietary methionine supplementation significantly improved haematological parameters, plasma methionine and total essential amino acid contents and hepatic glutamate-oxaloacetate transaminase (GOT) activities. Analysis of dose response using broken-line regression on the basis of SGR and PPV versus dietary methionine level estimated the optimum dietary methionine requirements of juvenile M. amblycephala to be between 8.5 and 8.4 g kg À1 of diet (25.0 and 24.7 g kg À1 of protein) in the presence of 2.2 g kg À1 cystine, respectively. Hence, the corresponding total sulphur amino acids requirements of this species were calculated to be 10.7 and 10.6 g kg À1 of diet (31.5 and 31.2 g kg À1 of dietary protein).

Dietary methionine requirement of pre-adult blunt snout bream, (Megalobrama amblycephalaYih, 1955)

“…() reported that excessive L‐methionine could be used efficiently by the fish body, but that the fish developed cataracts when methionine was in short supply. This symptom was not found in other studies of juvenile M. amblycephala (Liao et al., ). However, excessive supplementation of crystalline L‐methionine in feed had no significant influence on growth or feed utilization efficiency in barred soapfish ( Diploprion bifasciatum ) (Twibell et al., ), grouper ( Epinephelus coioids ) (Luo et al., ) or Japanese flounder (Alam et al., ).…”

“…Blunt snout bream, Megalobrama amblycephala , also known as Wuchang bream, is a major cultured freshwater fish species in China. However, knowledge of their methionine requirement is only known for juvenile fish (Liao et al., ), with the dietary methionine requirements estimated as 0.84–0.85% of the diet. No information is available on dietary methionine requirements for pre‐adult M. amblycephala .…”

Dietary vitamin A requirement of juvenile Wuchang bream ( Megalobrama amblycephala ) determined by growth and disease resistance

“…Production in China was approximately 0.72 million tons in 2012 (Ministry of Agriculture of the People's Republic of China, 2013). Recently, several nutritional requirement studies have been published for M. amblycephala such as protein and lipid (Li et al, 2010(Li et al, , 2012a, carbohydrate/lipid ratios (Li et al, 2012b), carbohydrate (Zhou et al, 2013a), protein (Habte-Tsion et al, 2013, essential amino acids (Habte-Tsion et al, 2015;Liao et al, 2014;Ren et al, 2013), and vitamins and minerals (Jiang et al, 2013;Jiang et al, 2012;Miao et al, 2015;Wan et al, 2014;Zhou et al, 2013b;Shao et al, 2012). However, the growth and immune responses associated with VA in Wuchang bream have not been studied.…”

Dietary leucine level affects growth performance, whole body composition, plasma parameters and relative expression of TOR and TNF-ɑ in juvenile blunt snout bream, Megalobrama amblycephala

“…Increasing information on the basic nutrient requirements of this species have been reported in the last decade, and 31-34% dietary protein and 7-8% lipid were determined to be optimal for growth (Habte-Tsion et al, 2013;Li et al, 2010;Li et al, 2013;Ren et al, 2015a). The dietary EAA requirements of blunt snout bream including arginine , lysine , methionine (Liao et al, 2014), threonine and phenylalanine have been determined for this fish species. However, there is no available data on dietary leucine requirement of blunt snout bream.…”