Hostname: page-component-78c5997874-s2hrs Total loading time: 0 Render date: 2024-11-04T18:48:14.995Z Has data issue: false hasContentIssue false
  • English
  • Français

Birth weight responses to shearing ewes in early to mid gestation

Published online by Cambridge University Press:  18 August 2016

S.T. Morris ,
S.N. McCutcheon  and
D.K. Revell
S.T. Morris
Affiliation:
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
S.N. McCutcheon
Affiliation:
Office of the Assistant Vice Chancellor (Research), Massey University, Palmerston North, New Zealand
D.K. Revell
Affiliation:
Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
Get access

Abstract

This study compared the effect on foetal growth of shearing ewes in very early pregnancy (day 50) with the effect of shearing later in pregnancy (day 70 or 100). One hundred and sixty ewes were allocated at day 49 of pregnancy to four ‘time of shearing’ treatments — pregnancy day 50 (P50), P70, P100 (no. = 45 ewes per treatment) and unshorn (shearing of this group occurred 43 days after weaning) (no. = 25); two methods of shearing (by standard comb and cover comb); and two levels (1 or 2) of pregnancy/rearing rank. All ewes had been mated over a 28-day period and grazed pasture throughout the trial. The mid point of lambing was 27 August 1996. Live weights of ewes (corrected for fleece weight) were not influenced by shearing time at any stage except at day 45 of lactation when ewes shorn at P50, P70 or P100 were about 3⋅0 kg lighter than unshorn ewes. Shearing method had no effect on ewe live weight. Time of shearing and shearing method had no effect on ewe greasy fleece production or wool tensile strength. Shearing significantly (P < 0⋅05) influenced the birth weight of single- (by 0⋅7 to 0⋅8 kg) but not twin-born lambs. Maternal plasma triiodothyronine concentration increased proportionately by 0⋅47 to 0⋅85 (P < 0⋅05) and lasted for at least 20 days in response to shearing irrespective of time of shearing. No difference in plasma insulin concentration was detected between shearing groups but plasma glucose concentration proportionately increased by 0⋅06 to 0⋅16 (P < 0⋅05) for 10 to 20 days after shearing. These results indicate that shearing between day 50 and 100 of pregnancy can increase lamb birth weights and that the response is associated with an increase in thyroid hormone concentrations in the maternal circulation.

Keywords

birth weighteweslambspregnancyshearing
Type
Ruminant nutrition, behaviour and production
Information
Animal Science , Volume 70 , Issue 2 , April 2000 , pp. 363 - 369
Copyright
Copyright © British Society of Animal Science 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Austin, A.R. and Young, N.E. 1977. The effects of shearing pregnant ewes on lamb birth weights. Veterinary Record 100: 527–529.Google ScholarPubMed
Bell, A.W., McBride, B.W., Slepetis, R., Early, R.J. and Currie, W.B. 1989. Chronic heat stress and prenatal development in sheep. I. Conceptus growth and maternal plasma hormones and metabolites. Journal of Animal Science 67: 3289–3299.CrossRefGoogle ScholarPubMed
Bigham, M.L., Sumner, R.M.W., Hawker, H. and Fitzgerald, J.M. 1983. Fleece tenderness — a review. Proceedings of the New Zealand Society of Animal Production 43: 73–78.Google Scholar
Black, H.J. and Chestnutt, D.M.B. 1990. Influence of shearing regime and grass silage quality on the performance of pregnant ewes. Animal Production 51: 573–582.Google Scholar
Dabiri, N., Morris, S.T., Parker, W.J., McCutcheon, S.N. and Wickham, G.A. 1995. Productivity and cold resistance in ewes pre-lamb shorn by standard or cover comb. Australian Journal of Agricultural Research 46: 721–732.CrossRefGoogle Scholar
Dalton, D.C., Knight, T.W. and Johnson, D.L. 1980. Lamb survival in sheep breeds on New Zealand hill country. New Zealand Journal of Agricultural Research 32: 167–173.CrossRefGoogle Scholar
Fisher, D.A., Dussault, J.H., Sack, J. and Chopra, I.J. 1977. Ontogenesis of hypothalamic-pituitary-thyroid function and metabolism in man, sheep, and rat. Recent Progress in Hormone Research 33: 59–116.Google Scholar
Flux, D.S., Mackenzie, D.D.S. and Wilson, G.F. 1984. Plasma metabolite and hormone concentrations in Friesian cows of differing genetic merit measured at two feeding levels. Animal Production 38: 377–384.Google Scholar
Hahn, P. and Hassanali, S. 1982. The effect of 3, 5, 3-triiodothyronine on phospoenol pyruvate carboxykinase, fatty acid synthetase and malic enzyme activity in liver and brown fat of fetal and neonatal rats. Biology of the Neonate 41: 1–7.CrossRefGoogle Scholar
Kenyon, P.R., Morris, S.T., Revell, D.K. and McCutcheon, S.N. 1999. Improving lamb birthweight through mid to late pregnancy shearing: a review of recent studies. Proceedings of the New Zealand Society of Animal Production 59: 70–72.Google Scholar
Maruo, T., Matsuo, H. and Mochizuki, M. 1991. Thyroid hormone as a biological amplifier of differentiated trophoblast function in early pregnancy. Acta Endocrinologica 125: 58–66.Google ScholarPubMed
Maund, B.A. 1980. Shearing of ewes at housing. Animal Production 30: 481.Google Scholar
Mellor, D.J., Slater, J.S. and Matheson, I.C. 1975. Effect of changes in ambient temperature on maternal plasma and allantoic fluid from chronically catheterised ewes during the last two months of pregnancy. Research in Veterinary Science 18: 219–221.CrossRefGoogle ScholarPubMed
Morris, S.T. and McCutcheon, S.N. 1997. Selective enhancement of growth in twin foetuses by shearing ewes in early gestation. Animal Science 65: 105–110.CrossRefGoogle Scholar
Rattray, P.V., Thompson, K.F., Hawker, H. and Sumner, R.M.W. 1987. Pastures for sheep production. In Livestock feeding on pasture (ed. Nicol, A.M.), pp. 89–103. New Zealand Society of Animal Production occasional publication no. 10.Google Scholar
Statistical Analysis Systems Institute. 1985. SAS user’s guide, statistics, version 5 edition. SAS Institute Inc., Cary, NC.Google Scholar
Symonds, M.E., Bryant, M.J. and Lomax, M.A. 1986. The effect of shearing on the energy metabolism of the pregnant ewe. British Journal of Nutrition 56: 635–643.CrossRefGoogle ScholarPubMed
Symonds, M.E., Bryant, M.J., Shepherd, D.A.L. and Lomax, M.A. 1988. Glucose metabolism in shorn and unshorn pregnant sheep. British Journal of Nutrition 60: 249–263.CrossRefGoogle ScholarPubMed
Thompson, G.E., Bassett, J.M., Samson, D.E. and Slee, J. 1982. The effects of cold exposure of pregnant sheep on foetal plasma nutrients, hormones and birthweight. British Journal of Nutrition 48: 59–64.CrossRefGoogle Scholar
Vipond, J.E., King, M.E., Inglis, D.M. and Hunter, E.A. 1987. The effect of winter shearing of housed pregnant ewes on food intake and animal performance. Animal Production 45: 211–221.Google Scholar
Weekes, T.E.C., Sasaki, Y. and Tsuda, T. 1983. Enhanced responsiveness to insulin in sheep exposed to cold. American Journal of Physiology 244: E335–E345.Google ScholarPubMed