Li Jinnan

Effect of Dietary Alanyl-glutamine Supplementation on Growth Performance, Development of Intestinal Tract, Antioxidant Status and Plasma Non-specific Immunity of Young Mirror Carp (Cyprinus carpio L.)

Exogenous alanyl-glutamine (Aln-Gln) was evaluated for its effects on growth performance, intestinal structure and function, antioxidant status and non-specific immunity of young carp (Cyprinus carpio L.). Six diets supplemented with 0, 2.5, 5.0, 7.5, 10.0, or 15.0 g · kg−1 of Aln-Gln were fed to fish for 12 weeks. Supplementation with 7.5, 10.0, or 15.0 g · kg−1 of Aln-Gln significantly increased weight gain rate (WGR), protein efficiency ratio (PER), but feed conservation rate (FCR) and survival were not affected (P>0.05). The intestinal fold height and number, digestive enzyme, Na+, K+-ATPase activities was found to be significantly high (P<0.05) with increasing dietary Aln-Gln supplementation up to 7.5 g · kg−1, but there were no significant differences for Aln-Gln supplementation from 7.5 to 15.0 g · kg−1. The glutathione peroxidase (GPX) activity, glutathione (GSH), superoxide dismutase (SOD) activity increased and malondialdehyde (MDA) levels decreased significantly (P<0.05) in the intestine, hepatopancreas, plasma and muscles. The plasma complement-3 (C3) and complement-4 (C4) levels were significantly (P<0.05) improved at 5.0 g · kg−1 level and decreased when over 7.5 g · kg−1. The plasma lysozyme (LSZ) activity increased significantly (P<0.05) at 7.5, 10.0, or 15.0 g · kg−1 level. In summary, the results showed that Aln-Gln improved growth performance, development and function of the intestine, the activity of the antioxidant defense system and the plasma non-specific immunity of the carps. The optimal Aln-Gln level was 8.24 g · kg−1 diet for WGR based on broken-line regression model analysis.

Effects of Dietary Protein and Temperature on Growth and Flesh Quality of Songpu Mirror Carp

The study was conducted to demonstrate the effects of dietary protein and water temperature on growth and flesh quality of Songpu mirror carp (Cyprinus carpio) at an initial weight (165.24±5.08) g. Practical diets were formulated to contain five protein levels (29.12%, 31.46%, 34.49%, 38.17%, and 40.13%), and each diet was randomly assigned triplicate groups of 15 fishes at three temperatures (18°C, 22°C, and 26°C) in the recirculation system. Fishes were fed twice daily to apparent satiation for 56 days. Results indicated that fishes had higher weight gain rate at 22°C and 26°C than that at 18°C (P 0.05). Based on the weight gain rate, dietary protein level 29.12% could meet the requirement of the body at 18°C, 22°C, or 26°C. Crude protein, crude lipid, moisture and ash of muscle had no significant differences among those treatments (P>0.05). pH (after 24 h) of muscle was the highest at 18°C and the lowest at 22°C (P 0.05). No significant differences on shear force, water holding capacity, collagen, glycogen and lactate among all the treatments were found (P>0.05). It was concluded that when C. carpio fed to apparent satiation, the growth mainly depended upon temperature. Dietary protein could not significantly affect flesh quality, but temperature significantly affected pH of muscles. A dietary protein level 29.12% could meet the requirement of the body at 18°C, 22°C, or 26°C.