Effect of methionine on intestinal enzymes activities, microflora and humoral immune of juvenile Jian carp (cyprinus carpiovar. Jian)

Abstract

An 8-week feeding experiment was conducted to determine the effect of dietary methionine supplementation on intestinal microflora and humoral immune of juvenile Jian carp (initial weight of 9.9 ± 0.0 g) reared in indoor flow-through and aerated aquaria. Eight amino acid test diets (350 g kg )1 crude protein, CP), using fish meal, soybean-condensed protein and gelatin as intact protein sources supplemented with crystalline amino acids, were formulated to contain graded levels of methionine (0.6-22.0%) at a constant dietary cystine level of 3 g kg )1 . Each diet was randomly assigned to three aquaria. Growth performance and feed utilization were significantly influenced by the dietary methionine levels (P < 0.05). Maximum weight gain, feed intake occurred at 12 g kg )1 dietary methionine (P < 0.05). Methionine supplementation improved hepatopancreas and intestine weight, hepatosomatic and intestine index, intestinal c-glutamyltransferase and creatine kinase activity, Lactobacillus count, Bacillus count, lysozyme activities, lectin potency, sim-immunoglobulin M content, addiment C3,C4 contents and serum total iron-binding capacity and declined Escherichia coli and Aeromonas counts. Quadratic regression analysis of weight gain against dietary methionine levels indicated that the optimal dietary methionine requirement for maximum growth of juvenile Jian carp is 12 g kg )1 of the dry diet in the presence of 3 g kg )1 cystine. KEY WORDS

Effects of graded levels of dietary methionine hydroxy analogue on immune response and antioxidant status of immune organs in juvenile Jian carp (Cyprinus carpio var. Jian)

“…Furthermore, studies had demonstrated that MHA was converted into L-methionine for effective utilization in chicken liver, rat liver and hog kidney [11]. Our laboratory previous study found that dietary DL-methionine could improve serum lysozyme activity, total iron-binding capacity, haemagglutination titre, complement 3, 4 and immunoglobulin M (IgM) contents in Jian carp [4]. These appear that MHA can also affect fish immune response, which needs investigation.…”

“…Studies indicated that methionine deficiency led to depressed survival rate, as well as reduced growth performance in Jian carp (Cyprinus carpio var. Jian) [4], rainbow trout (Oncorhynchus mykiss) [5] and juvenile red drum (Sciaenops ocellatus) [6]. Supplement methionine hydroxy analogue (MHA), a common used synthetic methionine source, to methionine-deficient diets increased survival rate and also improved growth performance of rainbow trout [5] and juvenile red drum [6].…”

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

“…The present study showed that liver weight was significantly increased with dietary methionine supplementation, and similar result was observed in juvenile Jian carp, Cyprinus carpio var. Jian (Tang et al 2009). In juvenile rockfish (Yan et al 2007) and Atlantic salmon (Espe et al 2008), HSI was influenced by dietary methionine level.…”

Effect of dietary isoleucine on the immunity, antioxidant status, tight junctions and microflora in the intestine of juvenile Jian carp (Cyprinus carpio var. Jian)

“…in ileum of rabbits [39]. Moreover, our laboratory studies showed some amino acids such as methionine [40], histidine [8] and valine [9] affect microbial population in the intestine of Jian carp. So it is necessary to investigate the relationship between dietary Ile and intestinal microbial population in fish.…”