不同盐度下饵料蛋白质含量对凡纳滨对虾生长、体成份和肝胰腺组织结构的影响

Effects of dietary protein levels on growth,survival,body composition and hepatopancreas histological structure of the white shrimp,Litopenaeus vannamei,at different ambient salinities

设计了蛋白质含量为20.61%、30.52%、40.43%和50.34%的4种饵料(分别为CP20、CP30、CP40和CP50),研究饵料蛋白质含量对不同盐度下(分别为低盐度LS 2、中盐度MS 22和高盐度HS 32)凡纳滨对虾[(0.0144±0.0047)g]生长、成活及体成份的影响,测定了不同处理组对虾的肝胰腺指数(HIS)和肥满度(CF),试验为期8周。结果显示:(1)盐度对凡纳滨对虾的生长、成活、肥满度和灰分含量均有显著影响(P<0.05),而对肝体指数、体粗蛋白、体粗脂肪和水分无显著影响(P>0.05),中盐度组对虾各指标均最高,其次为高盐度组,低盐度组最低;中、高盐度组对虾的增重率、特殊体重(长)增长率均显著高于低盐度组对虾(P<0.05),而中、高盐度组对虾的各生长指标无显著差异(P<0.05);(2)饵料蛋白质含量对凡纳滨对虾的各生长指标和体粗蛋白含量影响显著(P<0.05),对其它各指标影响不显著(P<0.05)。各盐度下,对虾生长和体粗蛋白含量均随饵料蛋白质含量升高而升高,投喂CP20的对虾组显著低于其它各处理组(P<0.05);肥满度和肝体指数均先随饵料蛋白质含量升高至40.43%而升高,然后稍有下降;饵料蛋白质含量对各盐度下对虾成活率影响均不显著(P>0.05)。(3)双因素方差分析结果显示,盐度和饵料蛋白质含量,除对体灰分含量存着着显著的交互作用外(P<0.05),对其它体生化成份含量、生长及体形态指标的交互作用均不显著(P>0.05)。(4)饲料蛋白质含量明显影响了凡纳滨对虾肝胰腺的组织结构,投喂CP30和CP40饵料的对虾肝小体基膜完整,投喂CP40对虾的肝小体中还出现了大量的存储细胞(R细胞);而投喂CP20饵料的对虾肝小体分布松散,R细胞数量较小,并且部分肝小体基膜破损;而投喂CP50饵料的对虾的肝小体排列紧密,且B细胞内出现大量内容物质。结果提示,提高饵料蛋白质含量虽然在一定程度上加快对虾的生长速度和增加肥满度,但是并不能提高低盐底下凡纳滨对虾的成活率。饲料中蛋白质含量的不适宜,尤其是含量过低,会导致对虾肝胰腺的结构发生变化甚至发生不同程度的病理变化。

An 8-week trial was conducted to investigate the effects of dietary protein levels which were 20.61, 30.52, 40.43 and 50.34% （named CP20, CP30, CP40 and CP50 respectively） on the growth, survival, body composition of the white shrimp, Litopenaeus vannamei, at three ambient salinities which were 2, 22 and 32 respectively. The results showed that ambient salinity had significant effects on shrimp growth, survival, conditional factor（CF） and body ash, while no significant differences were observed in the hepatosomatic index （HSI）, body crude protein, lipid and moisture. Shrimps at 22 were the highest in all the parameters followed by these at 32 and 2. Weight gain, specific growth rate for both weight and body length of shrimps at 32 and 22 were significantly higher than those at 2, while no differences were found in shrimps at 32 and 22. Dietary protein levels only significantly affected the growth performance, body crude protein, CF and HSI of the shrimps. Weight gain and the body crude protein content of shrimps increased with the increasing of dietary protein level, and shrimps fed with CP20 showed significant lower growth performance and body crude protein. CF and HSI increased with the dietary protein levels increasing to CP40 firstly, and then decreased slightly when fed with CP50. Dietary protein levels had no effect on the survival shrimp at all the ambient salinities. Ambient salinity and dietary protein level only had significant interaction on the body ash content, while no significant interaction effects were observed in other parameters. Tubules of shrimp fed with CP30 and CP40 had the normal structure, though CP40 increased the number of R cells. Tubules of shrimps fed with CP20 had relatively fewer R cells and arranged incompactly. And the basal membranes of partial tubules were in disrepair. While tubules of shrimps fed with CP50 compactly arranged with much ambiguous materials in B cells. The results indicated that though the growth performance and conditional factor could be increased by increasing dietary protein level, low survival rate at low salinity did not enhance. And improper content of dietary protein, especially extremely lower dietary protein, would result in pathological changes of the hepatopancreans＇ histological structure.