| The experiment was divided into two parts: the starvation and feeding experiment of Litopenaeus vannamei and the experiment of feeding frequency.Through the study on the growth of the Litopenaeus vannamei,the composition of body nutrition,the metabolic ability and immunity,the scientific breeding scheme was explored,the cost of intensive culture was reduced and the production was raised.Experiment one: Litopenaeus vannamei [(1.84±0.23)g average weight] were fed with three diets for 24 d to observe the effects of different carbohydrates on the growth performance,body composition and related metabolism in two states(hunger and refeeding).The experiment including four treatment with three replicates,treatment A was the starvation group,the control group,the experimental group named S1,S2 and S3(sugar sources: glucose,sucrose,cornstarch,respectively).In the experiment,after 12 d starving,the weight of Litopenaeus vannamei declined obviously,the lipid decreased,the contents of water and ash increased significantly(P<0.05),while the contents of protein decline slightly.And during starvation growth,the content of liver glycogen and muscle glycogen was significantly lower compared with that of initial,decreases significantly and then increases,but the trend of hepatic glycogen was more evident.Meanwhile,the results suggested that the hepatopancreas lipase,phosphofructokinase,hexokinase,and glutamine synthetase were higher than the starvation group and it was significant(P<0.05).The weight gain in S3 group was the highest after refeeding,the experimental groups were lower than the control group even though it was not significant,the liver glycogen content in S1 was significantly lower,while the muscle glycogen in S3 was significantly higher(P<0.05).The activity of LPS and HK increased greatly during the early days of refeeding(P<0.05).The results showed that corn starch had good effects on the growth and metabolism of Litopenaeus vannamei after refeeding,and provide guidance for the future conservation of bait.Experiment two: An 8-week feeding trial in a 3×2 two-factorial design was conducted to study the effects of feeding frequency(7/d,5/d,2/d,respectively)and carbohydrate(sucrose and cornstarch)on growth,body composition,metabolic and immune ability in Litopenaeus vannamei [initial average weight(0.38+0.01)].The experimental results show that:(1)the feeding frequency of Penaeus vannamei gonad development had no significant effect(P>0.05),but influentially affected the end body mass,weight gain,special growth rate,fatness and feed coefficient(P<0.05);(2)Litopenaeus vannamei coarse frequency ash,feeding water,and crude protein content had no essential effect(P<0.05),S3 group,the content of crude fat was significantly higher than the other groups;(3)The activity of malate dehydrogenase and pepsin significantly increase in the hepitopancrease of Litopenaeus vannamei(P<0.05),while kinase and lipase is the highest(P<0.05)after feeding 5 times /d.The interaction between feeding frequency and sugar source has a significant effect on the activity of glucokinase in the hepitopancrease of Litopenaeus vannamei(P<0.05);(4)feeding frequency on Litopenaeus vannamei hepatopancreatic AKP and ACP,the activity of SOD significantly(P<0.05),no crucial influence on T-AOC,ALT and AST in haemolymph and hepatopancreas in(P>0.05).The activities of AKP and SOD in the hepatopancreas of S2,S3,C2 and C3 group were significantly higher than those of low frequency and low frequency feeding S1 and C1 group(P<0.05).In conclusion,raising the feeding frequency is beneficial to the growth of Litopenaeus vannamei and the immune ability. |
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