The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime

McGregor, B. A., Butler, K. L. and Ferguson, M. B. 2012, The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime, Animal production science, vol. 52, no. 1, pp. 35-43.

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Title The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime
Author(s) McGregor, B. A.
Butler, K. L.
Ferguson, M. B.
Journal name Animal production science
Volume number 52
Issue number 1
Start page 35
End page 43
Total pages 9
Publisher CSIRO Publishing
Place of publication Collingwood, Vic.
Publication date 2012-01-04
ISSN 1836-0939
1836-5787
Keyword(s) age effects
genotype
mohair production
nutritional management
weaning management
Summary As mean fibre diameter (MFD) is the primary determinant of mohair price we aimed to quantify the lifetime changes in mohair MFDas Angora goats aged and grew. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of sire, dam, birthweight, birth parity, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFLwt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. A restricted maximum likelihood growth curve model was developed for relating MFD to FFLwt, age and other measurements.Asimple way of describing the results is:MFD= k (FFLwt)b E; where k is a parameter that can vary in a systematic way with shearing(age), breed, weaning weight, sire, dam and individual; b is a parameter that is the same for nearly the whole study; and E are independent errors from a log-normal distribution. The analysis shows that ^b = 0.34, with s.e. (^b) = 0.021. Thus, mohair MFD was allometrically related to the cube root of FFLwt over the lifetime of Angora goats. However, the allometric proportionality constant differed in a systematic way with age at shearing, genetic strain, weaning weight, sire, dam and individual. For Texan-breed goats, MFD decreased as weaning weight increased (P = 0.00016). The findings indicate that management factors that affect liveweight and weaning weight have lifetime effects on mohair fibre diameter and therefore the value of mohair and the profitability of the mohair enterprise.
Language eng
Field of Research 070202 Animal Growth and Development
Socio Economic Objective 830599 Primary Animal Products not elsewhere classified
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2012, CSIRO
Persistent URL http://hdl.handle.net/10536/DRO/DU:30046899

Document type: Journal Article
Collection: Centre for Material and Fibre Innovation
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