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The relationship between the incidence of medullated fibres in mohair and live weight over the lifetime of Angora goats

McGregor, B.A., Butler, K.L. and Ferguson, M.B. 2013, The relationship between the incidence of medullated fibres in mohair and live weight over the lifetime of Angora goats, Small ruminant research, vol. 113, no. 1, pp. 90-97, doi: 10.1016/j.smallrumres.2013.02.007.

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Title The relationship between the incidence of medullated fibres in mohair and live weight over the lifetime of Angora goats
Author(s) McGregor, B.A.ORCID iD for McGregor, B.A. orcid.org/0000-0002-4574-4236
Butler, K.L.
Ferguson, M.B.
Journal name Small ruminant research
Volume number 113
Issue number 1
Start page 90
End page 97
Total pages 8
Publisher Elsevier
Place of publication Amsterdam, The Netherlands
Publication date 2013-06
ISSN 0921-4488
Keyword(s) age effects
genetic effects
lifetime effects
live weight effects
shearing frequency
Summary The presence of even a small amount of medullated fibre, in otherwise high quality mohair, may have a pronounced adverse effect on its value and end-use potential. However, there is considerable confusion about the effects, if any, of environmental variables and management upon the incidence of medullated fibres in mohair. This study examined how the incidence of medullated fibres (Med, % by number) is related to the fleece-free live weight (FFLwt) of Angora goats of different genetic origins over their lifetime, and how the relationship varies with other lifetime factors. Measurements were made over 11 shearing periods of 6 months, on a population of Angora goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birth weight, birth parity, weaning weight, live weight, fleece growth and fleece quality were taken for castrated males (wethers) (n = 94 animals). A restricted maximum likelihood (REML) model was developed for log10(Med + 1), which allowed the observations of the same animal at different ages to be correlated in an unstructured manner. Med varied between 0.1% and 4.3%. The median average FFLwt during a shearing interval increased from 15 kg at 1 year old to 59 kg at 6 years old. Generally, within each shearing interval, Med increased with increasing average FFLwt. However, the size and shape of the relationship differed greatly between shearing ages. For example, at 3.5 years of age Med increased from about 1.1% at an average FFLwt of 26 kg to 2.6% at 50 kg, whilst at 5.0 years of age Med only changed from 1.4% at 32 kg to 1.6% at 56 kg. Goats with mixed genetic parentage showed an increase in Med at some shearings, particularly at younger ages. Variation in animal nutrition, as measured by live weight change during shearing periods, did not affect Med. The results supplement our earlier findings that mohair mean fibre diameter and clean mohair fleece weight, but not staple length, are greater in larger Angora goats. Live weight needs to be taken into account in genetic evaluation of the incidence of medullated fibres. We conclude that any advantage in handling fewer but larger Angora goats rather than more but smaller goats will come at the detriment of producing lower quality mohair, both in terms of increased Med and mean fibre diameter.
Language eng
DOI 10.1016/j.smallrumres.2013.02.007
Field of Research 070202 Animal Growth and Development
070203 Animal Management
Socio Economic Objective 830599 Primary Animal Products not elsewhere classified
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2013, Elsevier
Free to Read? Yes
Free to Read Start Date 2014-07-01
Persistent URL http://hdl.handle.net/10536/DRO/DU:30057691

Document type: Journal Article
Collections: Institute for Frontier Materials
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Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.