Does mid-pregnancy shearing affect lamb fleece characteristics?
R.G. SHERLOCK, P.R.KENYON AND S.T. MORRIS
Institute of Veterinary, Animal and Biomedical Sciences, Massey
University, Palmerston North, New Zealand.
E-Mail:
NZSAP 2002 Abstract No. 16
Proceedings of the New Zealand Society of Animal Production 62:
57-60
Mid-pregnancy shearing has been promoted as a technique to
increase both lamb birth weight and survival in multiple-born lambs.
Mid-pregnancy shearing has also been shown to increase dam wool quantity
and quality and, in some instances, increase lamb growth rates until
weaning. It has also been suggested that shearing of the dam during
pregnancy results in a change in the lamb’s fleece characteristics. The
aim of this study was to further investigate the effect of dam shearing
treatment on lamb fleece characteristics. Thirty-one singleton and 29
twin-born lambs were born to either mid-pregnancy shorn or unshorn
Romney ewes. At 6 months of age the lambs were midside sampled (to allow
measurement of staple length (SL), washing yield, loose wool bulk,
colour and mean fibre diameter (MFD)). A skin biopsy was taken from the
midside to measure the ratio of secondary to primary follicles. The
lambs were shorn three weeks later and a fleeceweight was obtained.
Lambs born to shorn dams had a higher MFD (32.9 vs. 31.3µm, P<0.05)
and had slightly whiter wool (0.1 vs. 0.3, P=0.07) than their
counterparts born to unshorn ewes but did not differ for yield, SL or
bulk. The higher MFD found in the lambs born to shorn ewes was
associated with a decrease in the number of secondary follicles
(P<0.05) without a significant decrease in the number of primary
fibres. There was a significant interaction (P=0.05) between birth rank
and shearing treatment on fleeceweight such that twin-born lambs born to
shorn dams tended to have heavier fleeces (by 170g) than those born to
unshorn dams, this relationship was not observed in singleton lambs.
This study suggests that for singleton lambs, mid-pregnancy shearing of
the dam will have no appreciable effect on wool value. However in
twin-born lambs an increase in fleece weight may offset any decreased
value due to higher MFD.
Keywords: NZSAPAB;
mid-pregnancy shearing; micron; follicle development
Last Updated 30/07/2002
