Wang Changan

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.

Requirement of essential amino acids for Hucho taimen juvenile.

Feeding experiments were conducted with protein diets(PD)and protein-free diets(FPD) for Hucho taimen(6.8-7.3 g),the diets(PD) was prepared by casein and gelatin as protein source with high biological values.The whole body amino acid composition was determined at the beginning and the end of the study.The requirements of Hucho taimen for essential amino acids(EAA) were determined based on the daily increment and daily maintenance requirement of each EAA in fish body.Fish were raised in tanks.There were 2 diets,each diet was randomly assigned to triplicate groups of 25 fish.During the experiment,the water temperature fluctuated from 23 ℃ to 25 ℃,and the dissolved oxygen was 6.4 mg/L to 7.5 mg/L.The experiment was conducted for 28 days.Compared with the FPD fish,the survival rate,the feed coefficient rate,the weight gain and crude lipid were increased significantly(P 0.05).The daily maintenance requirement of EAA(except trytophan) accounted for 20% to 30% of the sum of daily increment and daily maintenance requirement,and accounting for 54.52% of tryptophan.So the daily maintenance requirement of EAA can not be ignored.The minimum requirements of EAA needed to satisfy the requirements of Hucho taimen[g/(100 g body weight)/d]were:Threonine 0.040,Valine 0.041,Methionine 0.027,Isoleuline 0.034,Leucine 0.067,Phenylalanine 0.035,Lysine 0.068,Histidine 0.110,Arginine 0.050.When dietary protein level was 42%,the minimum contents of EAA in the dietary(g/kg diet) were as follows:Threonine 4.17,Valine 4.24,Methionine 2.84,Isoleuline 3.56,Leucine 6.99,Phenylalanine 3.64,Lysine 7.18,Histidine 11.53,Arginine 5.19 and Trytophan 0.76.