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The evaluation of selection in a crossing ram breed to improve litter size in sheep.

Published online by Cambridge University Press:  21 November 2017

S. Hoste  and
C. Smith
S. Hoste
Affiliation:
Welsh Agricultural College, Llanbadarn Fawr, Aberystwyth, Dyfed, Wales, SY23 3AL
C. Smith
Affiliation:
A.F.R.C. Animal Breeding Research Organisation, West Mains Road, Edinburgh, Scotland, EH9 3SQ
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Extract

Five genotypes were compared as sires of crossbred ewes from Scottish Blackface dams. These included Border Leicester (BL), New Zealand Romney (R) (from two group breeding schemes where selection had emphasized litter size), and three lines from the composite A.B.R.O. Damline (DL). Selection of the male and female lambs in the purebred DL flock was:

  1. a) for an average of 5.5 years on a Ewe Index of eight week litter weight (Martin and Smith, 1980).

  2. b) for an average of 3.5 years on a Testis index, combining testis size (adjusted for body weight) and Ewe Index of eight week litter weight both components receiving approximately equal weight and

  3. c) a random bred control.

These five genotypes (two rams per genotype per year for five years) were group mated (sires of individual ewes were not known) with Scottish Blackface ewes on an upland farm in Ayrshire.

Type
Beef Production
Information
Proceedings of the British Society of Animal Production (1972) , Volume 1986 , March 1986 , pp. 27
Copyright
Copyright © The British Society of Animal Production 1986

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References

James, J.W. (1975). Genetic considerations in large field experiments. In Developments in Field Experimental Design and Analysis (ed. Bofinger, V.S. and Wheeler, J.L.), pp.155–167. BULL Commonwealth Agric. Bureaux, No.50Google Scholar
Martin, T.G. and Smith, C. (1980). Studies on a selection index for improvement of litter weight in sheep. Anim. Prod. 31: 81–85 Google Scholar
Smith, C., King, J.W.B., Nicholson, D., Wolf, B.T., and Eampton, P.R., 1979. Performance of crossbred sheep from a synthetic damline. Anim. Prod. 22: 1–9.Google Scholar