广西罗非鱼链球菌病流行菌株PCR鉴定和PFGE基因型分析

为评估吉富罗非鱼(GIFT Oreochromis niloticus)抗病F₅代的选育效果，以F₀代群体和奥尼罗非鱼(Oreochromis aureus×O.niloticus)作为对照组，对F₅代42个家系的抗病性能及生长性能进行评估。对42个家系进行人工腹腔注射感染无乳链球菌 (Streptococcus agalactiae)后，分别有36个和22个家系的感染成活率比F₀代和奥尼罗非鱼高，各家系的抗病育种值为 – 0.158~0.086；生长性能测定发现，42个家系中有27个家系的绝对增长率大于F₀代；感染成活率与体质量之间的遗传相关系数为 – 0.033。综合分析各个家系的感染成活率、抗病育种值和绝对增长率，筛选出抗病力强且生长速度快的家系7个(2^#、3^#、4^#、6^#、28^#、31^#和35^#)，可作为F₆代选育和苗种扩繁的亲本。结果表明，经过5个世代的针对性选育，吉富罗非鱼的抗病性能和生长性能均得到了明显改善，选育效果显著。

Effect of Epinephelus coioides, Chanos chanos, and GIFT tilapia in polyculture with Penaeus monodon on the growth of the luminous bacteria Vibrio harveyi

To assess the effects of selective breeding in GIFT tilapia (Oreochromis niloticus), we measured the disease resistance and growth performance of 42 families of GIFT tilapia F₅ generation, taking F₀ generation and hybrid tilapia (Oreochromis aureus×O.niloticus) as control groups. The results show that the survival rates of 36 families of F₅ generation were higher than that of F₀ generation, and the survival rates of 22 families were higher than that of hybrid tilapia after Streptococcus agalactiae infection. The disease-resistant breeding value was – 0.158 – 0.086 among different families. The absolute growth rates of 27 families were higher than that of F₀ generation. The correlation coefficient between the survival rate and the body mass was negative, and the quantitative value was – 0.033. According to the comprehensive comparison among the survival rate, disease-resistant breeding value and absolute growth rate for 42 families of F₅ generation, we have screened seven families (2^#, 3^#, 4^#, 6^#, 28^#, 31^#, 35^#) which were best-performing and can be used as breeding parents of F₆ generation. The results indicate that the disease resistance and growth performance of GIFT tilapia were improved significantly after five generations' selective breeding.