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RESEARCH ARTICLE
Contents Vol 57(8)

The effect of mid- and late-pregnancy shearing of hoggets on lamb birthweight, weaning weight, survival rate, and wool follicle and fibre characteristics

P. R. Kenyon A C , R. G. Sherlock A , S. T. Morris A and P. C. H. Morel B
+ Author Affiliations
- Author Affiliations

A Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.

B Institute of Food Nutrition and Human Health, Massey University, Palmerston North, New Zealand.

C Corresponding author. Email: P.R.Kenyon@massey.ac.nz

Australian Journal of Agricultural Research 57(8) 877-882 https://doi.org/10.1071/AR05336
Submitted: 23 September 2005  Accepted: 7 March 2006   Published: 9 August 2006

Abstract

Pregnancy shearing of mature ewes has been shown to influence lamb birthweight and sometimes lamb survival to weaning and wool follicle characteristics. However, the effects of shearing hoggets in mid- or late-pregnancy under New Zealand’s pastoral conditions have not been examined. This study was designed to determine the effects of mid- and late-pregnancy shearing on lambs born to Romney hoggets. Single-bearing hoggets were either shorn at average day 79 of pregnancy (n = 74), at average day 119 (n = 80), or left unshorn (n = 76) while their twin-bearing counterparts were either shorn at average day 79 of pregnancy (n = 18) or left unshorn (n = 12).

Mid-pregnancy shearing was found to increase the birthweights of singles (by 0.32 kg, P < 0.05) in comparison with unshorn ewes; however, this relationship was not observed in twins. Neither mid- nor late-pregnancy shearing affected lamb survival to weaning. Singles born to late-pregnancy shorn ewes had whiter wool (P < 0.05) in comparison with lambs born to unshorn dams. Dam treatment had no other effects on follicle or wool characteristics.

The results of this study indicate that mid-pregnancy shearing of hoggets can be used as a technique to increase birthweight in single lambs but not twin-born lambs. Pregnancy shearing had no effect on lamb survival rates to weaning, whereas shearing in late-pregnancy had minor effects on wool colour that would be unlikely to affect wool value in Romneys. Shearing in mid-pregnancy had no effect on either progeny follicle or wool characteristics.

Additional keywords: sheep, ewe lamb, yearling ewe, wool follicle development.


Acknowledgments

The authors thank Mr Dean Burnham and Mr Aaron Hicks for the technical assistance provided, and Massey University and Meat and Wool Innovation for funding this study.


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