Please use this identifier to cite or link to this item: https://une.intersearch.com.au/unejspui/handle/1959.11/2770
Title: Across population genetic parameters for wool, growth, and reproduction traits in Australian Merino sheep: 1. Data structure and non-genetic effects
Contributor(s): Safari, E (author); Fogarty, N M (author); Gilmour, A R (author); Atkins, K D (author); Mortimer, S I (author); Swan, Andrew (author); Brien, F D (author); Greeff, J C (author); Van Der Werf, Julius Herman (author)orcid 
Publication Date: 2007
DOI: 10.1071/AR06161
Handle Link: https://hdl.handle.net/1959.11/2770
Abstract: Accurate estimates of adjustment factors for systematic environmental effects are required for genetic evaluation systems. This study combined data from 7 research resource flocks across Australia to estimate genetic parameters and investigate the significance of various environmental factors for production traits in Australian Merino sheep. The flocks were maintained for several generations and represented contemporary Australian Merino fine, medium, and broad wool bloodlines over the past 30 years. Over 110 000 records were available for analysis for each of the major wool traits, with over 2700 sires and 25 000 dams. Univariate linear mixed animal models were used to analyse 6 wool, 4 growth, and 4 reproduction traits. This first paper outlines the data structure and the non-genetic effects of age of the animal, age of dam, birth-rearing type, sex, flock, bloodline, and year, which were significant with few exceptions for all production traits. Age of dam was not significant for reproduction traits and fleece yield. Generally, wool, growth, and reproduction traits need to be adjusted for age, birth-rearing type, and age of dam before the estimation of breeding values for pragmatic and operational reasons. Adjustment for animal age in wool traits needs to be applied for clean fleece weight (CFW), greasy fleece weight (GFW), and fibre diameter (FD) with inclusion of 2 age groups (2 years old and >2 years old), but for reproduction traits, inclusion of all age groups is more appropriate. For GFW, CFW, and hogget weight (HWT), adjustment for only 2 dam age groups of maiden and mature ewes seems sufficient, whereas for birth (BWT), weaning (WWT), and yearling (YWT) weights, adjustments need to be applied for all dam age groups. Adjustment for birth-rearing type (single-single, multiple-single, multiple-multiple) is appropriate for wool, growth, and reproduction traits. The implications of adjustment for non-genetic effects are discussed.
Publication Type: Journal Article
Source of Publication: Australian Journal of Agricultural Research, 58(2), p. 169-175
Publisher: CSIRO Publishing
Place of Publication: Melbourne, Australia
ISSN: 0004-9409
Field of Research (FOR): 060412 Quantitative Genetics (incl Disease and Trait Mapping Genetics)
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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