ABSTRACT

An attempt was made in the present study to elucidate the (co)variance components and genetic parameters of fiber traits in Kashmir Merino sheep population using multivariate animal model. The data pertained to a total of 6836 sheep lambs born over a period of 21 years (1997–2017) and included information on different fiber traits [greasy fleece weight at first (GFW1) and second (GFW2) clips; and fiber diameter (FD) and staple length (SL) at second clip]. Genetic analysis was undertaken using average information restricted maximum likelihood (AI-REML) algorithm in WOMBAT program. The model incorporated six fixed (sex of lamb, season and period of birth, farm of origin, breed and type of birth) and two random effects (direct additive genetic and maternal genetic effects without any covariance between them) in it. The additive genetic heritability estimates for fiber traits were 0.300 ± 0.031; 0.289 ± 0.022; 0.254 ± 0.029 and 0.189 ± 0.028 for GFW1, GFW2, FD, and SL, respectively. The maternal genetic heritability estimates were very low for all traits under study. The genetic correlation between different traits was positive and estimates ranged from moderate to high. The results from present study imply that the variation in these traits has genetic basis which can be exploited in the selection programmes for their improvement. The correlation between different fiber traits was found to be favorable, which can lead to indirect selection response upon formulation of efficient breeding programmes.

摘要

本研究尝试使用多元动物模型阐明克什米尔美利奴绵羊种群中纤维性状的（共）方差成分和遗传参数。数据涉及 21 年（1997-2017 年）期间出生的总共 6836 只绵羊羔，包括不同纤维特性的信息[初剪羊毛重量 (GFW1) 和第二剪羊毛重量 (GFW2)；和纤维直径 (FD) 和纤维长度 (SL) 在第二个夹子]。在 WOMBAT 程序中使用平均信息限制最大似然 (AI-REML) 算法进行遗传分析。该模型包含六个固定的（羔羊性别、出生季节和时期、原产地、品种和出生类型）和两个随机效应（直接加性遗传和母体遗传效应，它们之间没有任何协方差）。纤维性状的加性遗传遗传力估计值为 0.300 ± 0.031；0.289±0.022；GFW1、GFW2、FD 和 SL 分别为 0.254 ± 0.029 和 0.189 ± 0.028。对于所研究的所有性状，母体遗传遗传力估计值都非常低。不同性状之间的遗传相关性呈正相关，估计值从中等到高。目前的研究结果表明，这些性状的变异具有遗传基础，可以在选择程序中加以利用以进行改进。发现不同纤维性状之间的相关性是有利的，这可以在制定有效的育种计划时导致间接选择反应。对于所研究的所有性状，母体遗传遗传力估计值都非常低。不同性状之间的遗传相关性呈正相关，估计值从中等到高。目前的研究结果表明，这些性状的变异具有遗传基础，可以在选择程序中加以利用以进行改进。发现不同纤维性状之间的相关性是有利的，这可以在制定有效的育种计划时导致间接选择反应。对于所研究的所有性状，母体遗传遗传力估计值都非常低。不同性状之间的遗传相关性呈正相关，估计值从中等到高。目前的研究结果表明，这些性状的变异具有遗传基础，可以在选择程序中加以利用以进行改进。发现不同纤维性状之间的相关性是有利的，这可以在制定有效的育种计划时导致间接选择反应。