The Effects Of Dietary Protein Level、 Feeding Frequency And Feeding Level On Growth And Health Of Procambarus Clarkii

The present experiment investigated the effects of dietary protein levels,feeding frequency and feeding level on growth performance,body composition,muscle composition,antioxidant capacity and physiological function of red swamp crayfish(Procambarus clarkii Girard).1.Protein requirement of red swamp crayfish(Procambarus clarkii)at three different growth stages.Protein requirements are different at different growth stage.Generally,crayfish in the early stage of life usually have a high protein requirements.An 8-week experiment was performed to investigate the effects of different dietary protein levels on growth performance,body composition and antioxidant capacity of Procambarus clarkii at three different growth stages.The results showed that with the increase of dietary protein level,weight gain rate(WGR)and specific growth ratio(SGR)of crayfish increased first and then stabilized in three different growth stages.With the increase of dietary protein level,the feed coefficient ratio(FCR)decreased first and then stabilized.In the first and second growth stage,the crude protein increased first and then stabilized;in the third growth stage,the lowest crude protein content was observed in the group fed with 250 g/kg dietary protein.With the increase of dietary protein level,both the superoxidase dismutase(SOD)activity and the phenoloxidase(PO)activity increased in the first and second growth stage;in the third growth stage,after the dietary protein levels exceeded300 g/kg,both the SOD activity and the PO activity decreased.Based on these findings and a broken-line model of specific growth rate,the optimal diet protein levels for the crayfish with initial body weight of 0.026 g,1.04 g and 5.06 g,were 403.3 g/kg,358.8g/kg and 305.6 g/kg,respectively.2.The effects of feeding frequency and feeding level on growth performance and physiological function of Procambarus clarkiiThe present experiment investigated the effects of feeding frequency and feeding level on growth performance,body composition,muscle composition,and physiological function of red swamp crayfish(Procambarus clarkii).A total of 30 crayfish with an average initial body weight of(4.97 ± 0.11)g were selected as the subjects,and the experiment lasted 56 days,with three feeding frequencies(1,2 and 3 meals/day)and three feeding levels(3,4.5 and 6% body weight per day).The results are as follows:(1)In L6F2 group,the WGR and SGR were the highest,which were not significantly different from L4.5F2,L6F1 and L6F3 groups,but significantly higher than the other groups(P<0.05).(2)The feed coefficient ratio in L4.5F2 group was the lowest and significantly higher than that in L4.5F1,L6F1,L6F2 and L6F3 groups.The benefits of L4.5F2 and L4.5F3 were similar and significantly higher than those of other groups(P<0.05).(3)Feeding level and feeding frequency had significant interaction on crude fat and ash content of muscle(P<0.05),and there was no significant interaction between whole body and muscle moisture(P<0.05).(4)In L6F3 group,the survival rate was the highest and had no significant difference with L4.5F1 and L4.5F2 groups,but significantly higher than other groups(P<0.05).(5)Feeding level and feeding frequency had significant interaction on the activities of LZM,TP,AKP,ACP,MDA,SOD and CAT(P<0.05).Considering the growth and feed utilization,as well as the cost and benefit of culture,the optimal feeding level was 4.5% body weight per day and 2 meals/d.