Wonmongkol P, Sukhavachana S, Ampolsak K, Srisapoome P, Suwanasopee T, Poompuang S
Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok, Thailand.
Center for Advanced Study in Agriculture and Food, Institute for Advanced Studies, Kasetsart University, Bangkok, Thailand.
J Fish Dis. 2018 Feb;41(2):321-328. doi: 10.1111/jfd.12728. Epub 2017 Oct 24.
Columnaris disease is a major cause of mortality in tilapia hatcheries and commonly occurs during the summer season in Thailand. One way of reducing the problem is by selective breeding for increased disease resistance. The objective of this study was to estimate quantitative genetic parameters for resistance against columnaris in the Chitralada 4 strain of Nile tilapia. Data from 43 full-sib families (2,580 records) of fry (age = 32 ± 4 days post-hatch) were used in the analyses. Initially, fry were subjected to bath challenge with Flavobacterium columnare (LD concentration = 1.2 × 10 CFU/ml) for 14 days. Disease resistance was defined as the number of days from challenge until death (DD) or as a binary trait (dead/alive) on day 14. Linear animal and sire-dam models were used for DD, while threshold animal, threshold sire-dam, binary linear animal and binary linear sire-dam models were used for binary outcomes. Covariate effect of age, fixed effect of challenge day and random effects of the individual animals or sires and dams were included in the models. Mean survival was 32.4 ± 11.6%, and survival rates of the best and poorest families were 70% and 8%, respectively. The highest estimate of heritability (0.30 ± 0.025) was obtained under the threshold sire-dam model. Heritability estimates for DD (0.16 ± 0.034 and 0.17 ± 0.046) were comparable to those obtained from the threshold animal (0.15 ± 0.031) and the binary linear (0.14 ± 0.045 and 0.15 ± 0.044) models. The linear animal and sire-dam models for DD and the threshold sire-dam models performed equally with similar values of r (0.629, 0.628 and 0.627) and accuracy of selection (0.793, 0.793 and 0.791). This study reveals the potential of selective breeding to increase disease resistance to F. columnare in the studied population of Nile tilapia.
柱状病是罗非鱼孵化场中导致死亡的主要原因，在泰国通常发生于夏季。减少这一问题的一种方法是通过选择性育种来提高抗病能力。本研究的目的是估计尼罗罗非鱼奇塔拉达4品系对柱状病抗性的数量遗传参数。分析中使用了来自43个全同胞家系（2580条记录）的鱼苗（孵化后32±4天龄）的数据。最初，鱼苗用柱状黄杆菌（致死浓度=1.2×10CFU/ml）进行浸浴攻毒14天。抗病能力定义为从攻毒到死亡的天数（DD）或在第14天作为二元性状（死亡/存活）。对于DD，使用线性动物模型和父系-母系模型，而对于二元结果，使用阈值动物模型、阈值父系-母系模型、二元线性动物模型和二元线性父系-母系模型。模型中纳入了年龄的协变量效应、攻毒日的固定效应以及个体动物或父系和母系的随机效应。平均存活率为32.4±11.6%，最佳和最差家系的存活率分别为70%和8%。在阈值父系-母系模型下获得了最高的遗传力估计值（0.30±0.025）。DD的遗传力估计值（0.16±0.034和0.17±0.046）与从阈值动物模型（0.15±0.031）和二元线性模型（0.14±0.045和0.15±0.044）获得的估计值相当。DD的线性动物模型和父系-母系模型以及阈值父系-母系模型表现相当，r值相似（0.629、0.628和0.627），选择准确性也相似（0.793、0.793和0.791）。本研究揭示了选择性育种在提高所研究尼罗罗非鱼群体对柱状黄杆菌抗病能力方面的潜力。
