略阳乌鸡开产日龄遗传参数估计和FSHR基因序列变异与开产日龄的关联性分析

为从遗传参数估计和FSHR基因序列变异关联分析角度定量评估遗传效应对略阳乌鸡开产日龄的决定性,以同一批次孵化的675只略阳乌鸡母鸡为对象,测定开产日龄、开产到30周龄、40周龄和56周龄产蛋数,用单变量动物模型估计开产日龄的遗传力,用双变量动物模型估计开产日龄与产蛋数间遗传相关。用Sequenom MassARRAY法检测FSHR基因内3个错义突变Thr46Ile、Lys151Arg和Met335Thr的基因型,用单变量线性混合模型检测这些变异与开产日龄的关联性。结果表明:1)略阳乌鸡的平均开产日龄为(147.5±7.8)d,其中,75%的鸡会在151日龄前开产。30周龄平均产蛋数为(28.0±7.6)枚,40周龄平均产蛋数为(58.6±15.0)枚,56周龄平均产蛋数为(75.1±20.4)枚。2)略阳乌鸡开产日龄的遗传力为0.08(95 %置信区间:0.017~0.21)。开产日龄与各阶段产蛋数存在强负遗传相关性(r_A=-0.98,95 %置信区间:-1.0~-0.7),但呈现出中等偏弱的表型相关性(r_p=-0.59~-0.21)。各阶段产蛋数间存在较强的遗传(r_A=0.99,95 %置信区间:0.84~1.00)和表型相关(r_p=0.48~0.79)。3)在3个FSHR错义突变中,第46位Thr和第335位Met不保守,但第151位Lys在鸟类和哺乳动物中完全保守。3个错义突变与略阳乌鸡开产日龄的关联性均不显著(P>0.05)。综上,遗传效应对开产日龄的决定性较低,但开产日龄与产蛋数存在较强遗传相关性。这些结果建议,饲养管理是开产日龄更为有效的调控手段;依据开产日龄对产蛋数进行间接选择具有可行性,但选择准确性会随产蛋周期的延长而降低。

Estimation of genetic parameters and association analysis of FSHR gene sequence variation with age at the onset of egg laying of Lueyang black-boned chicken

This study estimated genetic parameters of age at the onset of egg laying(AOE)of Lueyang black-boned chicken(LBC)and tested the association of sequence variants of FSHR gene to quantitatively assess the genetic determinant for AOE. AOE and numbers of eggs from the onset of egg laying to 30(EN30), 40(EN40)and 56(EN56)weeks of age of 675 Lueyang black-boned chickens(LBC), which were hatched in the same time, were measured. The heritability of AOE was estimated using a univariate animal model, and the genetic correlation between AOE and EN was estimated using a bivariate animal model. The non-synonymous variants(Thr46Ile, Lys151Arg and Met335Thr)in the FSHR gene were genotyped by Sequenom MassARRAY platform. The associations of these variants with AOE were tested using a univariate linear mixed model. The results showed that: 1)The average AOE of LBC was(147. 5±7. 8)d, of which 75 % of the chickens would begin to lay an egg before 151 days. The average number of eggs at 30 weeks old was(28. 0±7. 6), (58. 6±15. 0)at 40 weeks old and(75. 1±20. 4)at 56 weeks old. 2)The heritability of AOE was 0. 08(95 % confidence interval, 0. 017-0. 21). There was a strong negative genetic correlation(-0. 98, 95 % confidence interval, -1. 0 - 0. 7)between AOE and EN at each stage, but there was a moderate(-0. 59 - 0. 21)phenotypic correlation between AOE and EN. There was a strong genetic(r_A=-0. 98, 95% confidence interval, 0. 84-1. 00)and phenotypic correlation(r_p=0. 48-0. 79)between EN at each stage. 3)Of the three FSHR non-synonymous mutations, Thr⁴⁶ and Met³³⁵ were not conserved, but Lys¹⁵¹ was completely conserved in birds and mammals. There was no significant association between this three non-synonymous mutations and AOE(P>0. 05). In conclusion, the genetic effects are weak determinant of AOE, but there is a strong genetic correlation between AOE and EN. The results suggest that feeding management is more efficient in determining AOE than breeding. It is feasible to indirectly select number of eggs according to AOE, but the accuracy of indirect selection decreases with increase of egg production time.