草鱼幼鱼生长性状和肌肉成分的遗传参数估计

为了研究草鱼幼鱼阶段生长性状和肌肉成分的遗传改良潜力。随机采集288尾人工繁育的4月龄草鱼幼鱼，基于12对微卫星标记，鉴定出来自16个家系（8个母本，9个父本）的273尾个体，各家系、母本和父本对应子代贡献率存在极显著差异（P<0.01）。对草鱼3个生长性状（体质量、体长和肥满度）和2个肌肉成分指标（粗蛋白含量和粗脂肪含量）比较发现，3个生长性状和粗蛋白含量在家系和母系半同胞间存在显著差异（P<0.05），而3个生长性状和2个肌肉成分指标在父系半同胞间差异均不显著（P>0.05）。基于动物模型和限制性最大似然法，草鱼4月龄体质量、体长、肥满度、粗蛋白含量和粗脂肪含量的遗传力估值分别为0.34、0.33、0.17、0.17和0.20，其中3个生长性状遗传力估值统计检验显著（P<0.05）。遗传相关分析显示，体质量与体长之间呈极显著的高度正相关（0.82, P<0.01），肥满度与体质量和2个肌肉成分之间存在显著的正相关（0.17-0.29, P<0.05）。研究表明，草鱼4月龄生长性状具有较高的选育潜力，并可通过体长选择实现对体质量的遗传改良；推测在草鱼生长改良过程中，可能会伴随肥满度和粗脂肪含量的变化，这应当引起重视。

Genetic parameter estimates of growth traits and flesh components in juvenile grass carp(Ctenopharyngodon idella)

Aimed to access the genetic effect on growth traits and flesh components in juvenile grass carp (Ctenopharyngodon idella). Total of 288 juvenile grass carp at four months of age which were random collected from artificial breeding program, and 273 of them were unambiguous assigned to sixteen full-sib families (from eight dams and nine sires) using twelve microsatellite. The contributions to the offspring by different families (full-sib and half-sib families) were showed with significant non-uniform distribution (P<0.01).Three growth traits (body weight, standard length, and condition factor) and two flesh components (protein and fat contents) of fish were detected in our study. The significant differences of three growth traits and protein content were detected among full-sib families and dam half-sib families (P<0.05), whereas, no significant differences of five traits were detected among sire half-sib families (P>0.05). The genetic parameters for these traits of juvenile grass carp were estimated using restricted maximum likelihood (REML) algorithm based on animal model. The heritability estimates for growth traits were 0.34 for body weight, 0.33 for standard length, and 0.17 for condition factor, which all significantly different from zero (P<0.05). Whereas, the heritability estimates for flesh components were 0.17 for protein content, and 0.20 for fat content, but not significantly from zero (P>0.05). Highly and positive genetic correlation was found between standard length and body weight (0.82, P<0.01). Meanwhile, significantly positive genetic correlations were showed between condition factor to other traits studied except standard length (0.17-0.29, P<0.05). Therefore, selection for increased standard length is expected to produce favorable improvement in body weight, but it may lead to unfavorable changes in condition factor and fat content. This should be taken into account in practical breeding programs.