Multivariate Animal Model-based Analysis of Fiber Traits in Kashmir Merino Sheep

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

本研究试图利用多元动物模型阐明克什米尔美利奴羊群体纤维性状的（共）方差成分和遗传参数. 数据涉及21年（1997-2017年）期间出生的6836只绵羊羔羊，包括不同纤维特性的信息[第一次（GFW1）和第二次（GFW2）的油脂羊毛重量片段; 以及第二个剪辑处的纤维直径（FD）和短纤维长度（SL）. 遗传分析在袋熊程序中使用平均信息限制最大似然（AI-REML）算法进行. 该模型包含六个固定效应（羔羊性别、季节和出生期、产地、品种和出生类型）和两个随机效应（直接加性遗传效应和母体遗传效应，两者之间不存在任何协方差）. 纤维性状的加性遗传力估计值为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. 研究中所有性状的母体遗传力估计值都很低. 不同性状间的遗传相关性为正，估计值从中等到高不等. 本研究的结果表明，这些性状的变异具有遗传基础，可以在选择方案中加以利用，以改进它们. 不同纤维性状之间的相关性被发现是有利的，这可以导致在制定有效育种方案时产生间接选择反应.

KEYWORDS:

• Correlation
• heritability
• maternal
• model
• trait
• variance

关键词:

• 相关性
• 遗传力
• 母亲的
• 模型
• 特质
• 方差

Acknowledgments

The authors would like to acknowledge the support and guidance of Officers and staff members of Sheep Breeding and Research Farm Kralpathri and Gaobal, Jammu and Kashmir for continuous support and facilitation regarding the collection of data. The study was part of Professional Attachment Training (PAT) of the first author.

Disclosure statement

The authors have no conflict of interest to declare.