选择来自 25 个家系的 536 尾大菱鲆(Scophthalmus maximus L.), 进行为期 90 d 的低温(10.5~12℃)生长实验, 通过采集 18、54、90 d 的体质量、体长数据, 以特定生长率(SGR)为指标评估大菱鲆在低温下 18~54 d、54~90 d 这两个时间段的生长性能; 在一般动物模型中, 运用非求导约束极大似然法, 以 18 d 时的初始体质量、体长为协变 量, 估算低温生长 54、90 d 时大菱鲆数量性状遗传力, 并分析低温生长时长对它们的影响。结果显示, 大菱鲆低温 生长 18~54 d、54~90 d 的特定生长率分别为(0.869±0.181)%/d、(1.039±0.185)%/d(平均值±标准差), 后一时段特定 生长率比前一时段高 19.6%, 且经单因素 ANOVA 检验, 两个时间段特定生长率差异极显著(P<0.01), 说明随着低 温生长时间的延长, 大菱鲆的生长速度明显提高, 且家系间的生长性能差异很大。遗传力方面, 以第 54、90 天时 的测量体质量估计的遗传力分别为 0.440±0.129、0.548±0.150(平均值±标准误), 以第 54、90 天的测量体长估计的 遗传力分别为 0.301±0.108、0.494±0.142(平均值±标准误), 经 t 检验, 所有遗传力均达到极显著水平(P<0.01), 且 90 d 时的体质量、体长遗传力均明显高于 54 d 时的体质量、体长遗传力。结果证明, 在低温条件下, 生长时长对大菱 鲆数量性状遗传力的估算有明显影响, 且伴随低温生长时间的延长, 数量性状遗传力有明显的升高。从生长性能和 遗传力的实验结果可以得出, 利用低温生长时长来对大菱鲆进行耐低温品种的选育是可行的。
.) are a cold-water fish. Despite this, their growth rate is inhibited by exposure to low-temperatures in regions of China where cultured fish are reared in natural sea water that is <8℃ from December to March. To counter this, farmers extract deep well seawater or use heated natural seawater for cultivation. The extraction of a large amount of groundwater can result in a serious decrease in the water table and subsequent water shortage. Heating water is not only a waste of energy, but also it causes air pollution. Additionally, the costs of turbot cultivation increase significantly during this period. Improvements in performance traits and breeding of rapid growth varieties under low temperature conditions are important for two reasons: a reduction in pollution and ground water use and an increase in profitability. We evaluated the growth performance and heritability of growth traits in fish held for different durations at a range of low-temperatures (10.5–12℃). We used a total of 536 turbots from 25 family groups, including 13 full-sib families and 5 half-sib family groups (with 3 families derived from a cross of one dam with two sires and 2 families derived from a cross of one dam with three sires). During the 90-day study period, we measured the body weight (BW) and body length (BL) of each individual on days 18, 54, and 90. We calculated the SGR (specific growth rate) to describe growth performance. A general animal model was used to estimate the heritability of BW and BL after 54 and 90 days, with the initial body weight or initial body length (day 18) as a covariate. The specific growth rates (SGR) during days 18–54 and 54–90 were (0.869±0.181)%/d and (1.039±0.185)%/d (P<0.01), respectively. The specific growth rate between 54–90 d was 15.6% higher than in the previous period. The growth rate of turbot improved significantly with time and growth performance differed among families (P<0.01, one-way ANOVA). Turbot were able to adapt to low-temperature and prolonged holding at low temperature promoted cultivation of cold-resistant turbot. The heritabilities for body weight at 54 and 90 days were 0.440±0.129 and 0.548±0.150 (P<0.01), respectively; and for body length were 0.301±0.108 and 0.494±0.142 (P<0.01, t-test), respectively. The heritabilities for body weight and body length at 90 days were significantly higher than at 54 days. Our results suggest that the environmental effect decreases as duration of exposure to low temperature increases and a genetic effect can yield an increase in the growth of turbot. The heritability of body weight and body length increased with the duration of exposure to low-temperature, and the heritability of body length was higher than that for body weight. Thus, body length has greater utility as a breeding trait than body weight.
