美国品系尼罗罗非鱼的选育及其效果分析

Selection effects in American strain of Nile tilapia,Oreochromis niloticus

采用闭锁群体继代选育的方法(Closed population continuing selection and breeding method)对美国品系尼罗罗非鱼(Oreochromisniloticus)进行提纯选育,并利用选育获得的尼罗罗非鱼亲本作为母本,奥利亚罗非鱼(Oreochromis aureus)作为父本进行杂交生产子一代(简称"美奥"罗非鱼),再对子一代开展网箱养殖对比实验,以养殖实验的结果来评价选育尼罗罗非鱼的效果。结果表明:(1)实验组美国品系尼罗罗非鱼雌性后备亲本留种率P2世代分别比第P0、P1世代提高了103.16%和35.92%,P1世代比P0世代提高了49.47%,远高于同期未经选育的美国品系尼罗罗非鱼;(2)实验组"美奥"罗非鱼杂交组合的雌性亲本产苗量高达21.5万尾,高于对照组的21.2万尾;实验组产苗前期、高峰期和后期后代雄性率分别为96.27%、97.01%和95.70%,高于对照组的94.37%、95.65%和94.18%,但均呈现先升高后降低的变化趋势;(3)经过选育的"美奥"罗非鱼平均体长、平均体质量、绝对增重率、绝对增长率、特定生长率和生长指标均显著高于对照组(P<0.05);600g以上的罗非鱼所占的比例由对照组的51.2%增加到64.6%,增幅达到26.2%;头部比例有变小的趋势,头长/体长在0.30以下的比例由对照组的19.0%上升到32.07%,增幅达68.8%;实验组"美奥"罗非鱼的雄性率、单产及肥满度等主要经济指标均比对照组显著提高(P<0.05)。以上结果表明,"美奥"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。

In this study,closed population continuing selection and breeding method was carried out on the selective breeding of Nile tilapi（aOreochromisniloticus）with main selective characters such as growth rate,stripe identity in caudal fin and body shape.And the selection efficiencies of early generations（the second generation,P2）were evaluated.The results were as follows：（1）In selection generation（SG）population,the percentage of females suitable for selective breeding in P2 generation of Nile tilapia was 103.16%and 35.92%,higher than those in the foundation（P0） and first（P1）generations,and the percentage in P1 generation was 49.47%higher than that in P0 generation,which were much higher than that in control generation（CG）population that was not selected and bred;（2）Approximately 0.215 million hatchlings were produced by the cross of Nile tilapia and Oreochromisaureus in SG population,higher than that in CG population（0.212 million hatchlings）.The male rate of hybrids of Nile tilapi（a♀）×Oreochromisaureu（s♂）in SG population（＂Mei-Ao＂tilapia）were 96.27%,97.01%and 95.70%in pre-reproduction,middle-reproduction and post-reproduction stages,respectively,which were higher than that in CG population（94.37%,95.65%and 94.18%）;（3）The average body weight,average body length,absolute growth rate of body weight,absolute growth rate of body length,specific growth rate of body weight and growth index in SG population after different culturing duration were higher than those in CG population.The percentage of fish with above 600 gram size was 64.6%in＂Mei-Ao＂tilapias generated by SG population（test group）,which was 26.2%higher than that in＂Mei-Ao＂tilapias generated by CG population.The percentage of fish with head length/body length ratio under 0.30 was 32.07%in test group,which was 68.8%higher than that in control group.The survival rate,male rate,meat rate,average production per m2 and relative fatness in each test group of＂Mei-Ao＂tilapia were higher than those in the corresponding control group,and the feed coefficient was lower than that in control group（P〈0.05）.These results indicated that the selective effects of Nile tilapia were prominent and enough parental fish could be offered for crossbreeding of O.niloticus×O.aureus.