New Zealand Journal of Agricultural Research abstracts
Effects of pre-lamb shearing on feed intake and associated
productivity of May- and August-lambing ewes
N. DABIRI1
S. T. MORRIS1
M. WALLENTINE2
S. N. MCCUTCHEON1
W. J. PARKER3
G. A. WICKHAM1
1Department of Animal Science
Massey University
Palmerston North, New Zealand
2Department of Animal Science
Brigham Young University
Utah, USA
3Department of Agricultural and Horticultural
Systems Management
Massey University
Palmerston North, New Zealand
Abstract The effects of pre-lamb shearing on feed intake and
wool/lamb production of May (autumn)- and August (spring)-lambing ewes were
examined. Mixed age Border Leicester x Romney ewes mated to lamb in May or
August (60 ewes/lambing policy) were divided at random into two groups
(balanced for pregnancy status and liveweight). One group was shorn on Day 118
of pregnancy (P118) and the second group left unshorn. Measurement of pasture
intake was carried out over three periods before lambing (P113-117, P119-130,
and P141-144) and three periods after lambing (L (lactation day) 8-11, L21-25,
and L29-33) using intraruminal chromic oxide controlled release capsules.
Intake of ewes was not affected by shearing treatment during pregnancy or
lactation except during P141-144 when organic matter intake was significantly
greater for shorn ewes than for unshorn ewes (1739 +/- 58 versus 1526 +/- 59
g/day, P < 0.05). Ewe liveweights and condition scores were similar
for both shearing treatments during pregnancy and lactation. Over the period
P118-L13, pre-lamb shorn May-lambing ewes had significantly (P <
0.01) higher clean wool growth rates than comparable unshorn ewes (0.927 +/-
0.042 versus 0.721 +/- 0.048 mg/cm2 per day), but this effect was
not found in the August-lambing group (0.542 +/- 0.041 versus 0.641 +/- 0.045
mg/cm2 per day, P > 0.10). Clean wool growth rate was
greater in shorn ewes than in unshorn ewes (additive with effects of lambing
policy) over L13-84 (0.896 +/- 0.024 versus 0.801 +/- 0.025 mg/cm2
per day, P < 0.10). Lamb liveweights at birth and at three subsequent
measurement times to weaning were not affected by dam's shearing treatment. In
general, feed intake and productivity responses to pre-lamb shearing were
similar in both lambing policies, except for wool growth rates which were
influenced by shearing to a greater extent in May- than in August-lambing ewes.
Pre-lamb shearing is likely to be a viable option for autumn-lambing policies
and appears to have a more marked positive effect on wool growth of
autumn-lambing ewes than that of spring-lambing ewes.
Keywords pre-lamb shearing; feed intake; wool growth; fibre
diameter; lamb production; autumn lambing; spring lambing
New Zealand Journal of Agricultural Research, 1996, Vol. 39: 53-62
0028-8233/96/3901-0053 $2.50/0 (c) The Royal Society of New Zealand
1996
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