The relationship between cortical structure and fibre diameter in
primary and secondary wool fibres of yearling Perendale sheep
J.L. Dick, R.M.W. Sumner
AgResearch, Whatawhata Research Centre, Private Bag 3089,
Hamilton, New Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 31-34
Midside skin and wool samples were taken from 32 Perendale ewes at
12 months of age to investigate the relationship between fibre cortical
structure and fibre diameter in fibres derived from primary and
secondary follicles in sheep with varying loose wool bulk values. Bulk
was correlated to mean crimp frequency, staple length, mean fleece fibre
diameter, follicle curvature and proportion of para-mesocortex.
Medullation was present in only 2.8% of fibres and was not significantly
related to bulk. Primary fibres were coarser than secondary fibres
(37.4um vs 31.9um). The proportion of fibres was a bilateral cortical
cell type arrangement decreased with increasing fibre diameter. The
mean proportion of para-mesocortex was less in primary than secondary
fibres (19.2% vs 21.1%). There was a significant within sheep
relationship between proportion of para-mesocortex and fibre diameter.
While primary and secondary fibres were different in mean fibre diameter
and cortical structure, the relationship between cortical structure and
fibre diameter did not differ between the two follicle populations.
Consequently it appears unnecessary to differentiate between primary and
secondary fibres in future studies of fibre cortical structure and wool
bulk.
Keywords: NZSAPAB;
Perendale; loose wool bulk; wool follicle type; cortical structure
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Last Updated 25-01-1997
