Thoa Ngo Phu, Hamzah Azhar, Nguyen Nguyen Hong
Research Institute for Aquaculture No.1, Tu Son, Bac Ninh, Viet Nam.
National Prawn Fry Production & Research Center, Kg. Pulau Sayak, 08500 Kota Kuala Muda, Kedah, Malaysia.
Anim Reprod Sci. 2017 Sep;184:94-101. doi: 10.1016/j.anireprosci.2017.07.003. Epub 2017 Jul 6.
The present study examines genetic variation and correlated changes in reproductive performance traits in a red tilapia (Oreochromis spp.) population selected over three generations for improved growth. A total of 328 breeding females (offspring of 111 sires and 118 dams) had measurements of body weight prior to spawning (WBS), number of fry at hatching (NFH), total fry weight (TFW) and number of dead fry (NDF) or mortality of fry including unhatched eggs at hatching (MFH). Restricted maximum likelihood (REML) analysis in a multi-trait model showed that there are heritable genetic components for all traits studied. The heritability for WBS was very high (0.80). The estimates for traits related to fecundity (NFH, TFW) and survival (NDF) were low and they were associated with high standard errors. Genetic correlations of WBS with other reproductive performance traits (NFH, TFW and NDF) were generally positive. However, NFH was negatively correlated genetically with TFW. As expected, body measurements during growth stage exhibited strong positive genetic correlations with WBS. The genetic correlations between body traits and reproductive performance (NFH, TFW, NDF) were not significant. Correlated responses in reproductive traits were measured as changes in least squares means between generations or spawning years. Except for WBS that increased with the selection programs, the phenotypic changes in other reproductive traits observed were not statistically significant (P>0.05). It is concluded that the selection program for red tilapia has resulted in very little changes in reproductive performance of the animals after three generations. However, periodic monitoring of genetic changes in fecundity and fitness related traits such as NDF or MFH should be made in selective breeding programs for red tilapia.
本研究考察了三代选育以提高生长性能的红罗非鱼（Oreochromis spp.）群体的遗传变异以及繁殖性能性状的相关变化。总共328只繁殖雌鱼（111只雄鱼和118只雌鱼的后代）在产卵前进行了体重测量（WBS）、孵化时的鱼苗数量（NFH）、鱼苗总重（TFW）以及死鱼苗数量（NDF）或鱼苗死亡率（包括孵化时未孵化的卵，MFH）。多性状模型中的限制最大似然（REML）分析表明，所研究的所有性状均存在可遗传的遗传成分。WBS的遗传力非常高（0.80）。与繁殖力相关的性状（NFH、TFW）和存活率（NDF）的估计值较低，且标准误较高。WBS与其他繁殖性能性状（NFH、TFW和NDF）的遗传相关性总体为正。然而，NFH与TFW存在负遗传相关性。正如预期的那样，生长阶段的体尺测量与WBS表现出强烈的正遗传相关性。体尺性状与繁殖性能（NFH、TFW、NDF）之间的遗传相关性不显著。繁殖性状的相关反应通过代间或产卵年份最小二乘均值的变化来衡量。除了WBS随选育计划增加外，观察到的其他繁殖性状的表型变化在统计学上不显著（P>0.05）。得出的结论是，红罗非鱼的选育计划在三代后对动物的繁殖性能影响很小。然而，在红罗非鱼的选择性育种计划中，应定期监测繁殖力和与健康相关性状（如NDF或MFH）的遗传变化。
