[Objectives] This study aimed to determine the infection pathway and target organs of Streptococcus agalactiae in GIFT strain of Nile tilapia, thus providing theoretical basis for the breeding of disease-resistant til...[Objectives] This study aimed to determine the infection pathway and target organs of Streptococcus agalactiae in GIFT strain of Nile tilapia, thus providing theoretical basis for the breeding of disease-resistant tilapia and development of S. agalactiae vaccines.[Methods] GIFT strain of Nile tilapia was inoculated by S. agalactiae through intraperitoneal injection, oral gavage and in vitro immersion. The gill, spleen, liver and small intestine tissues of infected tilapia were collected for pathomorphological observation. Immunohistochemical localization was conducted using rabbit anti- S. agalactiae serum to identify the distribution pattern of S. agalactiae in various tissues of tilapia and its target organs via different infection pathways.[Results] GIFT strain of Nile tilapia could be infected by S. agalactiae via three artificial inoculation modes. Specifically, pathological changes occurred at 2 h post-inoculation in intraperitoneal injection and oral gavage groups, whereas tilapia in in vitro immersion group showed pathological changes at 5 h post-inoculation, and the lesion intensity in in vitro immersion group was slighter than that in intraperitoneal injection and oral gavage groups. Immunohistochemical localization indicated that the appearance time of positive signals in intraperitoneal injection group demonstrated an order of spleen→liver and gill→small intestine; positive signals in oral gavage group appeared in the order of small intestine→gill and spleen→liver; the appearance time of positive signals in in vitro immersion group showed an order of gill→spleen→liver and small intestine.[Conclusions] GIFT strain of Nile tilapia could be infected by S. agalactiae via intraperitoneal injection, oral gavage and in vitro immersion. The corresponding positive signals for pathogen infection were preferentially present in the spleen, intestine and gill tissues. Thus, preventing S. agalactiae contamination in aquaculture water and food sources is an effective measure to control the outbreak of S. agalactiae infections in tilapia under natural aquaculture conditions.展开更多
研究所用60个家系的吉富品系尼罗罗非鱼(GIFT strain Nile tilapia,Oreochromis niloticus;简称吉富罗非鱼)样本均为由世界渔业中心所在地马来西亚引进的原种。采用传统形态学测量方法,测量每尾鱼的体质量、体长、体高、体宽、头长、尾...研究所用60个家系的吉富品系尼罗罗非鱼(GIFT strain Nile tilapia,Oreochromis niloticus;简称吉富罗非鱼)样本均为由世界渔业中心所在地马来西亚引进的原种。采用传统形态学测量方法,测量每尾鱼的体质量、体长、体高、体宽、头长、尾柄长和尾柄高后进行主成分分析和相关分析,研究吉富品系尼罗罗非鱼群体内的形态差异。结果显示,吉富罗非鱼体高与体质量的相关性最大(R2=0.9002)。在体长与体质量对应的点状分布中,总群体、雌雄群体和每个家系群体中均呈现出2条带状,分布于2条带的个体间质量差异不显著(P>0.05),对应的个体数量之比接近常数0.7;体高、体宽、头长、尾柄长和尾柄高相应的分布则呈现出变异幅度迥异的条带。本研究表明,吉富罗非鱼群体内部在形态上存在差异。展开更多
用投喂添加色素的膨化颗粒饲料和观测排便相结合的方法,研究吉富品系尼罗罗非鱼(Genetic Improvement of Farmed Tilapias;GIFT)的摄食节律。结果发现,6个家系的吉富品系尼罗罗非鱼摄食具有明显的节律性,家系之间的摄食周期存在非常显...用投喂添加色素的膨化颗粒饲料和观测排便相结合的方法,研究吉富品系尼罗罗非鱼(Genetic Improvement of Farmed Tilapias;GIFT)的摄食节律。结果发现,6个家系的吉富品系尼罗罗非鱼摄食具有明显的节律性,家系之间的摄食周期存在非常显著差异(P<0.0001);t检验发现,各家系内摄食周期和排便周期的差异均不显著(P≥0.1097)。回归分析发现,摄食周期对生长无显著的影响(P=0.8988),但与摄食量之间存在显著的线性关系(R2=0.9679,P=0.0004)。对摄食节律聚类分析,6个家系可分为(1、2、6)、(3、4)、5共3个家系类别。该项研究能为GIFT的养殖投饵和进一步选育提供理论依据,为鱼类摄食节律研究提供方法上的参考。展开更多
通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响。在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在...通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响。在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在饱食投喂后15 h左右完全排空,达到投喂前水平,80%胃排空为9 h,也就是投喂后大约9 h恢复食欲。360尾试验鱼(初始体质量3.72 g)以不同的投喂频率(1 d 4次、1 d 3次、1 d 2次、2 d 4次、2 d 3次、2 d 2次)分组,每组设立3个平行组,随机养殖于18个网箱中,每箱养殖20尾鱼,按饱食量投饲膨化饲料。养殖期为6周。尼罗系吉富罗非鱼幼鱼在投喂频率为1 d 4次、1 d 3次和1 d 2次时特定生长率和饲料效率显著高于投喂频率为2 d 4次、2 d 3次和2 d 2次时(P<0.05);投喂频率为1 d 2次、2 d 4次、2 d 3次和2 d 2次时其摄食量显著低于1 d 4次和1 d 3次时(P<0.05)。随着投喂频率降低,鱼体水分含量逐步上升,脂肪和蛋白质含量逐步下降,其中1 d 4次、1 d 3次组鱼与2 d 2次组鱼有显著性差异(P<0.05)。各投喂频率组间的肝体指数无显著性差异(P>0.05)。3.7～48.0 g尼罗系吉富罗非鱼幼鱼的适宜投喂频率为1 d 2次,较2 d 2次、2 d 3次和2 d 4次时明显提高了生长速度和饲料效率,较1 d 3次、1 d 4次摄食量显著降低。2种试验结果较为一致。展开更多
用溴氯海因(BCDMH)和二溴海因(DBDMH)两种消毒剂对吉富罗非鱼进行急性毒性试验,研究吉富罗非鱼对海因类消毒剂的耐受性。结果表明:溴氯海因对吉富罗非鱼苗的24 h LC50、48 h LC50和安全浓度分别为9.61、8.66、2.11 mg/L,二溴海因对吉富...用溴氯海因(BCDMH)和二溴海因(DBDMH)两种消毒剂对吉富罗非鱼进行急性毒性试验,研究吉富罗非鱼对海因类消毒剂的耐受性。结果表明:溴氯海因对吉富罗非鱼苗的24 h LC50、48 h LC50和安全浓度分别为9.61、8.66、2.11 mg/L,二溴海因对吉富罗非鱼苗的24 h LC50、48 h LC50和安全浓度分别9.89、9.78、2.87 mg/L。展开更多
采用闭锁群体继代选育的方法对吉富品系尼罗罗非鱼(GIFT strain of Nile Tilapia)进行提纯选育,并利用选育获得的尼罗罗非鱼亲本作母本和奥利亚罗非鱼作父本进行杂交生产子一代,再对子一代开展网箱养殖对比试验,以养殖试验的结果来评价...采用闭锁群体继代选育的方法对吉富品系尼罗罗非鱼(GIFT strain of Nile Tilapia)进行提纯选育,并利用选育获得的尼罗罗非鱼亲本作母本和奥利亚罗非鱼作父本进行杂交生产子一代,再对子一代开展网箱养殖对比试验,以养殖试验的结果来评价选育尼罗罗非鱼(Oreochromis niloticus)的效果。结果表明:(1)选留系后备♀亲本选留数量及留种率都有了很大的提高;(2)"吉奥"杂交组合的产苗量和雄性率都有了不同程度的提高;(3)经过选育的"吉奥"罗非鱼的生长性能优于对照组;生长速度增加明显;头部比例有变小的趋势;(4)试验组"吉奥"罗非鱼的主要经济指标均比对照组有所提高,而饵料系数比对照组有所下降。以上结果表明,"吉奥"罗非鱼的选育效果良好,可为"尼奥"罗非鱼的苗种生产提供亲本保障。展开更多
基金Supported by Science and Technology Major Project of Guangxi(GK AA17204080-2)Guangxi Key Research and Development Program(GK AB16380077)+1 种基金Freshwater Fishery Industry Technology System of China(CARS-46)Aquathe Disease Resistance Breeding Project of Natinal Blue Granary plan(2019-2023)
文摘[Objectives] This study aimed to determine the infection pathway and target organs of Streptococcus agalactiae in GIFT strain of Nile tilapia, thus providing theoretical basis for the breeding of disease-resistant tilapia and development of S. agalactiae vaccines.[Methods] GIFT strain of Nile tilapia was inoculated by S. agalactiae through intraperitoneal injection, oral gavage and in vitro immersion. The gill, spleen, liver and small intestine tissues of infected tilapia were collected for pathomorphological observation. Immunohistochemical localization was conducted using rabbit anti- S. agalactiae serum to identify the distribution pattern of S. agalactiae in various tissues of tilapia and its target organs via different infection pathways.[Results] GIFT strain of Nile tilapia could be infected by S. agalactiae via three artificial inoculation modes. Specifically, pathological changes occurred at 2 h post-inoculation in intraperitoneal injection and oral gavage groups, whereas tilapia in in vitro immersion group showed pathological changes at 5 h post-inoculation, and the lesion intensity in in vitro immersion group was slighter than that in intraperitoneal injection and oral gavage groups. Immunohistochemical localization indicated that the appearance time of positive signals in intraperitoneal injection group demonstrated an order of spleen→liver and gill→small intestine; positive signals in oral gavage group appeared in the order of small intestine→gill and spleen→liver; the appearance time of positive signals in in vitro immersion group showed an order of gill→spleen→liver and small intestine.[Conclusions] GIFT strain of Nile tilapia could be infected by S. agalactiae via intraperitoneal injection, oral gavage and in vitro immersion. The corresponding positive signals for pathogen infection were preferentially present in the spleen, intestine and gill tissues. Thus, preventing S. agalactiae contamination in aquaculture water and food sources is an effective measure to control the outbreak of S. agalactiae infections in tilapia under natural aquaculture conditions.
文摘研究所用60个家系的吉富品系尼罗罗非鱼(GIFT strain Nile tilapia,Oreochromis niloticus;简称吉富罗非鱼)样本均为由世界渔业中心所在地马来西亚引进的原种。采用传统形态学测量方法,测量每尾鱼的体质量、体长、体高、体宽、头长、尾柄长和尾柄高后进行主成分分析和相关分析,研究吉富品系尼罗罗非鱼群体内的形态差异。结果显示,吉富罗非鱼体高与体质量的相关性最大(R2=0.9002)。在体长与体质量对应的点状分布中,总群体、雌雄群体和每个家系群体中均呈现出2条带状,分布于2条带的个体间质量差异不显著(P>0.05),对应的个体数量之比接近常数0.7;体高、体宽、头长、尾柄长和尾柄高相应的分布则呈现出变异幅度迥异的条带。本研究表明,吉富罗非鱼群体内部在形态上存在差异。
文摘用投喂添加色素的膨化颗粒饲料和观测排便相结合的方法,研究吉富品系尼罗罗非鱼(Genetic Improvement of Farmed Tilapias;GIFT)的摄食节律。结果发现,6个家系的吉富品系尼罗罗非鱼摄食具有明显的节律性,家系之间的摄食周期存在非常显著差异(P<0.0001);t检验发现,各家系内摄食周期和排便周期的差异均不显著(P≥0.1097)。回归分析发现,摄食周期对生长无显著的影响(P=0.8988),但与摄食量之间存在显著的线性关系(R2=0.9679,P=0.0004)。对摄食节律聚类分析,6个家系可分为(1、2、6)、(3、4)、5共3个家系类别。该项研究能为GIFT的养殖投饵和进一步选育提供理论依据,为鱼类摄食节律研究提供方法上的参考。
文摘通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响。在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在饱食投喂后15 h左右完全排空,达到投喂前水平,80%胃排空为9 h,也就是投喂后大约9 h恢复食欲。360尾试验鱼(初始体质量3.72 g)以不同的投喂频率(1 d 4次、1 d 3次、1 d 2次、2 d 4次、2 d 3次、2 d 2次)分组,每组设立3个平行组,随机养殖于18个网箱中,每箱养殖20尾鱼,按饱食量投饲膨化饲料。养殖期为6周。尼罗系吉富罗非鱼幼鱼在投喂频率为1 d 4次、1 d 3次和1 d 2次时特定生长率和饲料效率显著高于投喂频率为2 d 4次、2 d 3次和2 d 2次时(P<0.05);投喂频率为1 d 2次、2 d 4次、2 d 3次和2 d 2次时其摄食量显著低于1 d 4次和1 d 3次时(P<0.05)。随着投喂频率降低,鱼体水分含量逐步上升,脂肪和蛋白质含量逐步下降,其中1 d 4次、1 d 3次组鱼与2 d 2次组鱼有显著性差异(P<0.05)。各投喂频率组间的肝体指数无显著性差异(P>0.05)。3.7～48.0 g尼罗系吉富罗非鱼幼鱼的适宜投喂频率为1 d 2次,较2 d 2次、2 d 3次和2 d 4次时明显提高了生长速度和饲料效率,较1 d 3次、1 d 4次摄食量显著降低。2种试验结果较为一致。
文摘用溴氯海因(BCDMH)和二溴海因(DBDMH)两种消毒剂对吉富罗非鱼进行急性毒性试验,研究吉富罗非鱼对海因类消毒剂的耐受性。结果表明:溴氯海因对吉富罗非鱼苗的24 h LC50、48 h LC50和安全浓度分别为9.61、8.66、2.11 mg/L,二溴海因对吉富罗非鱼苗的24 h LC50、48 h LC50和安全浓度分别9.89、9.78、2.87 mg/L。
文摘采用闭锁群体继代选育的方法对吉富品系尼罗罗非鱼(GIFT strain of Nile Tilapia)进行提纯选育,并利用选育获得的尼罗罗非鱼亲本作母本和奥利亚罗非鱼作父本进行杂交生产子一代,再对子一代开展网箱养殖对比试验,以养殖试验的结果来评价选育尼罗罗非鱼(Oreochromis niloticus)的效果。结果表明:(1)选留系后备♀亲本选留数量及留种率都有了很大的提高;(2)"吉奥"杂交组合的产苗量和雄性率都有了不同程度的提高;(3)经过选育的"吉奥"罗非鱼的生长性能优于对照组;生长速度增加明显;头部比例有变小的趋势;(4)试验组"吉奥"罗非鱼的主要经济指标均比对照组有所提高,而饵料系数比对照组有所下降。以上结果表明,"吉奥"罗非鱼的选育效果良好,可为"尼奥"罗非鱼的苗种生产提供亲本保障。
