Department of Animal Science, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran.
Department of Animal Science, Islamic Azad University, Shahre-Qods Branch, Iran.
Vet Med Sci. 2023 Jan;9(1):380-390. doi: 10.1002/vms3.1038. Epub 2022 Dec 12.
There is large variation in genetic parameters in literature for growth traits in sheep. Reliable estimation of genetic parameters is required for developing breeding programmes.
The aim of this study was to aggregate results of different studies by meta-analysis to improve reliability of estimated parameters.
In the current study, 221 papers that have been published between 1995 and 2021 were reviewed. Using a random-effects model in the Comprehensive Meta-Analysis software, direct and maternal heritabilities, as well as, genetic and phenotypic correlations between growth traits were estimated in meat (M), wool (W) and dual-purpose (D) sheep breeds. The growth traits in this study were birth weight, 3-month weight, 6-month weight, 9-month weight and yearling weight.
The combined direct heritability was the lowest for birth weight (0.190 ± 0.004, 0.198 ± 0.003 and 0.196 ± 0.004 for M, W and D breeds, respectively) and the highest for yearling weight (0.264 ± 0.010, 0.304 ± 0.005 and 0.285 ± 0.020 for M, W and D breeds, respectively). The maternal heritability was the lowest for yearling weight (0.085 ± 0.003, 0.055 ± 0.002 and 0.052 ± 0.005 for M, W and D breeds, respectively) and the highest for 6-month weight (0.240 ± 0.088, 0.164 ± 0.001 and 0.162 ± 0.006 for M, W and D breeds, respectively). The phenotypic and genetic correlations were lower between the weights measured at more distant intervals. The lowest genetic correlation was observed between birth weight and yearling weight (0.290 ± 0.051 for W breeds).
The small standard errors could indicate that the aggregation of results from different studies improved the reliability of estimated parameters and reduced range of 95% confidence intervals. Hence, the results could be used with greater level of confidence in sheep breeding programmes.
文献中绵羊生长性状的遗传参数存在很大差异。为了制定育种计划，需要可靠地估计遗传参数。
本研究的目的是通过荟萃分析汇总来自不同研究的结果，以提高估计参数的可靠性。
在本研究中，回顾了 1995 年至 2021 年期间发表的 221 篇论文。使用 Comprehensive Meta-Analysis 软件中的随机效应模型，估计了肉用（M）、毛用（W）和兼用（D）绵羊品种的生长性状的直接和母体遗传力，以及生长性状之间的遗传和表型相关性。本研究中的生长性状包括初生重、3 月龄体重、6 月龄体重、9 月龄体重和周岁体重。
直接遗传力的综合值最低的是初生重（M、W 和 D 品种分别为 0.190 ± 0.004、0.198 ± 0.003 和 0.196 ± 0.004），最高的是周岁重（M、W 和 D 品种分别为 0.264 ± 0.010、0.304 ± 0.005 和 0.285 ± 0.020）。母体遗传力最低的是周岁重（M、W 和 D 品种分别为 0.085 ± 0.003、0.055 ± 0.002 和 0.052 ± 0.005），最高的是 6 月龄体重（M、W 和 D 品种分别为 0.240 ± 0.088、0.164 ± 0.001 和 0.162 ± 0.006）。测量间隔较远的体重之间的表型和遗传相关性较低。W 品种中观察到的最低遗传相关性是初生重与周岁重之间的相关性（0.290 ± 0.051）。
较小的标准误差表明，汇总来自不同研究的结果提高了估计参数的可靠性，并缩小了 95%置信区间的范围。因此，在绵羊育种计划中可以更有信心地使用这些结果。
