Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Crop and Pasture Science Crop and Pasture Science Society
Plant sciences, sustainable farming systems and food quality
Shopping Cart: ( empty )
You are here: Home > Journals > CP > AR05336
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.


References


Adalsteinsson S (1972) Experiments on winter shearing of sheep in Iceland. Acta Agriculturae Scandinavica 22, 93–96. open url image1

Auber L (1952) The anatomy of follicles producing wool-fibres with special reference to keratinisation. Transactions of the Royal Society of Edinburgh 52, 191–254. open url image1

Bedford J , Ross DA , Carnaby GA , Lappage J (1977) ‘WRONZ Fibre Bulkometer.’ (Wool Research Organisation of New Zealand Inc.: Christchurch, NZ)

Craig RL (1982) Breeding from Romney ewe hoggets in the Waihora Group Breeding Scheme. New Zealand Journal of Agricultural Science 16, 101–104. open url image1

Gavigan R , Rattray PV (2002) ‘100 more—a guide to hogget mating.’ (Meat and Wool Innovation: Wellington, NZ)

Hight GK (1982) Breeding and reproduction. In ‘Sheep production. Vol. 1’. (Eds GA Wickham, MF McDonald) pp. 169–198. (New Zealand Institute of Agricultural Science: Auckland, NZ)

IWTO (1998) ‘Specification IWTO-47-98. Measurement of the mean and distribution of fibre diameter using an optical fibre diameter analyser (OFDA).’ (International Wool Secretariat: London)

Kenyon PR (2002) The effect of mid-pregnancy shearing on lamb birthweight and survival to weaning. PhD thesis, Massey University, Palmerston North, New Zealand.

Kenyon PR, Morel PCH, Morris ST (2004) Effect of ewe liveweight and condition score at mating and mid-pregnancy shearing on twin lamb birthweights and growth rates to weaning. New Zealand Veterinary Journal 52, 145–149.
| PubMed |
open url image1

Kenyon PR, Morris ST, McCutcheon SN (2002c) Does an increase in lamb birthweight through mid-pregnancy shearing necessarily mean an increase in lamb survival rates to weaning? Proceedings of the New Zealand Society of Animal Production 62, 53–56. open url image1

Kenyon PR, Morris ST, Revell DK, McCutcheon SN (2002a) Nutrition during mid- to late-pregnancy does not affect the birthweight response to mid-pregnancy shearing. Australian Journal of Agricultural Research 53, 13–20.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Kenyon PR, Morris ST, Revell DK, McCutcheon SN (2002b) Maternal constraint and the birthweight response to mid-pregnancy shearing. Australian Journal of Agricultural Research 53, 511–517.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Kenyon PR, Morris ST, Revell DK, McCutcheon SN (2003) Shearing during pregnancy—review of a policy to increase birthweight and survival of lambs in New Zealand pastoral farming systems. New Zealand Veterinary Journal 51, 200–207.
| PubMed |
open url image1

Kenyon PR, Sherlock RG, Morris ST, Parkinson TJ (2005) The effect of maternal shearing and thyroid hormone treatments in mid-pregnancy on the birthweight, follicle, and wool characteristics of lambs. New Zealand Journal of Agricultural Research 48, 293–300. open url image1

MAF (2004) ‘MAF primary industry statistics New Zealand.’ (www.maf.govt.nz/statistics)

McCall DG, Hight GK (1981) Environmental influences on hogget lambing performance and the relationship between hogget and two-tooth lambing performance. New Zealand Journal of Agricultural Research 24, 145–152. open url image1

McMillan WH (1983) Hogget lamb mortality. Proceedings of the New Zealand Society of Animal Production 43, 33–36. open url image1

McMillan WH, McDonald MF (1983) Reproduction in ewe lambs and its effect on 2-year-old performance. New Zealand Journal of Agricultural Research 26, 437–442. open url image1

Minitab (2002) ‘Minitab Version 12.1.’ (Minitab Inc.: State College, PA)

Moore RW, McMillan WH, Dockrill G, Dow BW (1989) Lambing of Romney and Booroola cross hoggets with and without the F gene under different pasture allowances. Proceedings of the New Zealand Society of Animal Production 49, 281–283. open url image1

Morris ST, Kenyon PR, Burnham DL, McCutcheon SN (1999) The influence of prelamb shearing on lamb birthweight and survival. Proceedings of the New Zealand Grasslands Association 61, 95–98. open url image1

Morris ST, McCutcheon SN (1997) Selective enhancement of growth in twin foetuses by shearing ewes in early gestation. Animal Science 65, 105–110. open url image1

Morris ST, McCutcheon SN, Revell DK (2000) Birth weight responses to shearing ewes in early to mid gestation. Animal Science 70, 363–369. open url image1

Revell DK, Morris ST, Cottam YH, Hanna JE, Thomas DG, Brown S, McCutcheon SN (2002) Shearing ewes at mid-pregnancy is associated with changes in fetal growth. Australian Journal of Agricultural Research 53, 697–705.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Ryder ML , Stephenson SK (1968) ‘Wool growth.’ (Academic Press: London)

SAS (1985) ‘SAS user’s guide, statistics, version 5.’ (SAS Institute Inc.: Cary, NC)

Sherlock RG, Kenyon PR, Morris ST (2002) Does mid-pregnancy shearing affect lamb fleece characteristics? Proceedings of the New Zealand Society of Animal Production 62, 57–60. open url image1

Smeaton DC, Webby RW, Tarbotton IS, Clayton JB (2000) The effects of shearing Finnish Landrace × Romney ewes in mid-pregnancy on lamb survival, birthweights and other weights. Proceedings of the New Zealand Society of Animal Production 45, 58–60. open url image1

Standards Association of New Zealand (1984) ‘Method for the measurement of the colour of wool. NZS 8707, 1984.’ (Standards Association of New Zealand: Wellington, NZ)

Sumner RMW, Young SR, Upsdell MP (2003) Wool yellowing and pH within Merino and Romney fleeces. Proceedings of the New Zealand Society of Animal Production 63, 155–159. open url image1

Wallace JM (2000) Nutrient partitioning during pregnancy: adverse gestational outcome in overnourished adolescent dams. The Proceedings of the Nutrition Society 59, 107–117.
| PubMed |
open url image1