摘要
克氏原螯虾Procambarus clarkii隶属于甲壳纲(Crustacea)、十足目(OrderDecapoda)、爬行亚目(Reptantia)、螯虾科(Cambaridae)、原螯虾属(Procambarus)。原产美国南部和墨西哥北部,后由美国移植到日本的本州,20世纪30年代末期由日本引入我国南京附近,现已分布至十几个省市,成为归化于我国自然水体的一个种。最近十几年,种群发展很快,在有的湖泊和地区已成为优势种群,是重要的水产资源。克氏原螯虾是一种世界性的食用虾类,特别是欧美国家把其作为一种珍贵的水产经济动物而加以利用,是一种国际贸易的重要水产品。近年来,随着人们生活水平的提高,克氏原螯虾以其肉味鲜美、营养丰富、价格低廉等特点越来越受到国内消费者的欢迎。然而,在国内,目前克氏原螯虾基本上处于自然繁殖、人工捕捞的状况,还没有非常成功的人工繁殖和育苗的经验,因此面向国内外的克氏原螯虾市场都存在严重货源不足的问题。为此,采用人工培育的亲虾进行人工繁育是解决该问题的有效手段。健康虾类亲体的性腺发育成熟、繁殖力、受精率、胚胎孵化以及其后续自营养阶段幼体的质量和存活率,不仅与其所处生态环境中的物理因子(如水温、光照周期)息息相关,而且与亲体的营养状况关系密切。因此,为了培良性腺发育良好的克氏原螯虾亲体,从而获取大量高质量的幼体,本研究在前期本实验室对克氏原螯虾繁殖生物学和幼虾培育等进行初步研究的基础上,采用正交试验设计法中的L9(3~4)方法,分别探讨了物理因子(水温、光照周期)和营养因子(鱼粉、豆粉、维生素C、鱼油)对克氏原螯虾雌虾性腺发育及生长的影响,以期为克氏原螯虾亲虾的人工繁殖提供生态学和营养学上的资料。现将研究结果汇总如下:
1.研究了水温、光周期和饲料组成(纯植物性饲料、纯动物性饲料、植物性饲料+动物性饲料)对克氏原螯虾雌虾成活和性腺发育的影响。采用L9(3~4)正交设计法,探讨了水温、光周期和饲料组成3个因素对克氏原螯虾雌虾成活和性腺发育的影响。结果表明,各因素对克氏原螯虾雌虾成活率的影响大小为:水温>饲料组成>光周期,即在水温、光周期和饲料组成3个因素中,水温对克氏原螯虾雌虾成活率的影响最大,光周期对克氏原螯虾雌虾成活率的影响最小。3个因素的最优水平分别为:水温22℃、光照周期16L:8D、饲料组成为纯草鱼肉。
以性腺成熟系数(雌虾卵巢鲜重占雌虾体中的比例)为指标,3个因素对雌虾性腺发育的影响大小为:饲料组成>水温>光周期,其最优水平分别为:饲料组成为纯草鱼肉、水温28℃、光照周期16L:8D。根据本实验结果,综合考虑成活率和性腺发育情况,克氏原螯虾的亲虾培育可选择水温25~28℃之间、光照周期16L:8D,饲料中多添加鱼肉等动物性饲料。同时还应注意减小饲养密度,培育水草和投放竹筒、瓦片等供虾藏身之处以免发生同类残食的事件。
2.研究了饲料中鱼粉与豆粉的不同比例、维生素C和鱼油添加量对克氏原螯虾雌虾生长和繁殖力的影响。通过采用L9(3~4)正交设计法,以虾体重、雌虾抱卵率、单个雌虾抱卵量、性腺指数为指标,研究了饲料中鱼粉与豆粉不同比例、维生素C和鱼油添加量对克氏原螯虾雌虾生长和繁殖力的影响。结果表明,对克氏原螯虾雌体体重增长率影响程度的因素依次为:鱼油添加量、鱼粉与豆粉比例、维生素C添加量,即在鱼粉与豆粉的不同比例、维生素C和鱼油添加量这3个因素中,鱼油添加量对克氏原螯虾雌体体重增长率的影响最大,维生素C添加量的影响最小。综合考虑成本因素,3因素最优水平组合为:饲料中鱼粉与豆粉比例为1:1.5,维生素C添加量为0.04%,鱼油添加量为1.9%。
影响克氏原螯虾亲虾产卵率的重要性依次为鱼油、鱼粉与豆粉比例、维生素C,最优水平为饲料中鱼粉与豆粉比例为1:1.5,维生素C为0.06%,鱼油含量为3.8%;影响克氏原螯虾亲虾抱卵量的重要性依次为鱼油添加量、维生素C添加量、鱼粉与豆粉比例,最优水平为饲料中鱼粉与豆粉比例为1:1.5,维生素C添加量为0.06%,鱼油添加量为3.8%;影响雌虾性腺发育的重要性依次为鱼油添加量、维生素C添加量、鱼粉与豆粉比例,最优水平为饲料中鱼粉与豆粉比例为1:1.5,维生素C添加量为0.06%,鱼油添加量为3.8%。
实验结果说明,鱼粉与豆粉的合适配比、维生素C添加量、鱼油添加量对克氏原螯虾亲虾的生长和繁殖都有重要影响,而且在生长期和繁殖期应有不同的饲料配方,因为有的因素(如鱼油)添加量稍大能够促进繁殖,但对克氏原螯虾的生长却有一定的负面作用。
The red swamp crayfish Procambarus clarkii belongs to Decapoda,Reptantia, Cambaridae,Proeambarus.It originally distributed in the north of Mexico and the south of America,and was introduced into China by Japanese in the 1930s,Now it distributes in more than 10 provinces of China.This freshwater crawfish has been popular and become one Of the main aquatic animals in China recently due to its delicious taste and abundant nutrition.Now it has become one of the most important freshwater aquatic products in the cultivation.However,the natural resource of this crawfish has been decreased dramatically in recent several years because of its economic value and fishing without limit.So the artificial reproduction technique is imminently required to be developed for protecting the resource and for meet the need of the markets.A large number of studies showed that environmental factors(water temperature,photoperiod) and nutritional factors(fish meal,soybean meal,vitaminC,fish oil)were indispensable to
the normal development of gonad,reproductive performance and offspring quality for shrimp.Therefore our experiments were conducted to determine the physiological effects of above-mentioned factors on reproductive performance of the red swamp crayfish Procambarus clarkii by using the L9(3~4)table of orthogonal design.These studies may contribute greatly to the development of more effective and perfect artificial diets for shrimp broodstock,thus to make the red swamp crayfish breeding in a more economic and controllable way.Now experimental results were reviewed as follows.
1.The study deals with the effects of water temperature,photoperiod and dietary on reproductive performance of the red swamp crayfish Procambarus clarkii.It has been shown that the gonad development of shrimps is closely related to water temperature, photoperiod and dietary.The results showed that among these three factors,water temperature had the most important effect on the survival rate of the crawfish.The second important factor was diet.For survival rate,the optimum levels were:22℃of water temperature,16L(Light):8D(Dark)of photoperiod,feeding with grass carp meat. The gonadosomaticindex(GSI)of this female crawfish was mostly affected by the diet among the three experimented factors,followed by water temperature and photoperiod. For GSI,the optimum levels were:feeding with grass carp meat,28℃of water temperature and 16L:8D of photoperiod.These results suggest that taking both survival rate and ovarian development into consideration,the optimum breeding condition of this crawfish maybe 25~28℃of water temperature,16L:8D ofphotoperiod,feeding with the diet containing more meat,such as fish meat.At the same time,the culturing crawfish should not be too crowded in case they will attack each other,especially when exuviations occurs.
2.A study was done of the effect of different proportion between fish meal and soybean meal(1:3,1:2,1:1.5),vitaminC(0.02%,0.04%,0.06%),fish oil(1.9%, 2.85%,3.8%)on the growth,gonad development and spawning rate of the red swamp crayfish Procambarus clarkii by using the L9(3~4)table of orthogonal design.Results show that the effect on weight gain of the female crayfish were as follows:fish oil>proportion between fish meal and soybean>vitaminC,the optimum levels were: proportion between fish meal and soybean(1∶1.5),vitaminC(0.04%)and fish oil(1.9%), the effect on spawning rate were:fish oil>proportion between fish meal and soybean>vitaminC,the optimum levels were:proportion between fish meal and soybean(1: 1.5),vitaminC(0.06%)and fish oil(3.8%),the effect on spawning quantity were:fish oil>vitaminC>proportion between fish meal and soybean meal,the optimum levels were:proportion between fish meal and soybean meal(1:1.5),vitarninC(0.06%),fish oil (3.8%),the effect on gonad development were:fish oil>vitaminC>proportion between fish meal and soybean meal,the optimum levels were:proportion between fish meal and soybean meal(1:1.5),vitaminC(0.06%),fish oil(3.8%).It was suggested that the proper proportion between fish meal and soybean meal,vitaminC and fish oil be important and indispensable to reproductive performance of the red swamp crayfish Procambarus clarkii.However,excessive fish oil and vitaminC in diet was disadvantageous for growth of the red swamp crayfish Procambarus clarkii.
引文
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