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Effects of rapid inbreeding and of crossing of inbred lines on the body weight growth of sheep

Published online by Cambridge University Press:  02 September 2010

G. Wiener ,
G. J. Lee  and
J. A. Woolliams
G. Wiener
Affiliation:
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian EH25 9PS
G. J. Lee
Affiliation:
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian EH25 9PS
J. A. Woolliams
Affiliation:
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian EH25 9PS
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Abstract

Sheep of three hill breeds, Scottish Blackface, Cheviot and Welsh Mountain and the reciprocal crosses among these breeds were inbred (mostly by parent × offspring mating) for four generations to five levels with inbreeding coefficients ofO, 0·25 (I1), 0·38 (I2), 0·50 (I3) and 0·59 (I4). Inbred females were also mated to unrelated inbred males of the same breed type to produce line crosses (LC). Each type of dam (except LC and I4) was mated to produce lambs of up to three different inbreeding levels thus allowing the effects of the individual's own inbreeding to be separately assessed from the effects of maternal inbreeding. This study examined body weight at a sequence of ages from birth to 4 years of age with 2369 animals (ages up to 78 weeks old) or 1062 animals (2 to 4 years old) contributing to the analyses.

Inbreeding of the individual had a highly significant retarding effect on body weight and growth rate up to the I2 level for weights of lambs up to 24 weeks old, with a slight recovery in performance thereafter. For the later ages examined, the maximum depression was reached at the I3 stage. The partial recovery in performance at the higher levels of inbreeding for lambs less than 24 weeks of age was also noted within lines and did not therefore appear to arise only from a loss of lines as inbreeding proceeded. The effect of dam's inbreeding was to depress growth up to the I3 level and at most ages up to I4. Line-cross lambs were generally heavier (but not significantly so) than non-inbred (F2 and the pure equivalent, O2) and progeny of line-cross dams were similar in weight to those from other non-inbred (F1, or F2 and O1, or O2 dams) or slightly better. The more highly inbred the individuals the more, in general, they fell behind the weights of the corresponding non-inbreds as they grew older. Inbreeding may thus have permanently stunted the sheep.

There were no significant differences between purebred and crossbred sheep in the rate of inbreeding depression. Only at the ages of 3 and 6 weeks was there a significant difference between the three pure breeds in the changes in weight attributable to inbreeding. Up to the age of weaning (15 weeks) the changes with inbreeding of individuals could not be explained statistically in terms of dominance effects alone and non-allelic interactions may therefore also be involved. At all ages the effect of inbreeding of the dam was consistent with dominance effects alone.

Keywords

body weightgrowthinbreedingline differencessheep
Type
Research Article
Information
Animal Production , Volume 55 , Issue 1 , August 1992 , pp. 89 - 99
Copyright
Copyright © British Society of Animal Science 1992

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References

Doney, J. M. 1959. The effects of inbreeding in four families of Peppin Merinos. III. The influence of crude pituitary extract on inbred lambs. Australian Journal of Agricultural Research 10: 97–107.CrossRefGoogle Scholar
Doney, J. M. 1966. Inbreeding depression in grazing Blackface sheep. Animal Production 8: 261–266.Google Scholar
Ercanbrack, S. K. and Knight, A. D. 1981. Weaning trait comparisons among inbred lines and selected noninbred and randomly bred control groups of Rambouillet, Targhee and Columbia sheep. journal of Animal Science 52: 977–988.CrossRefGoogle ScholarPubMed
Ercanbrack, S. K. and Knight, A. D. 1983. Yearling trait comparisons among inbred lines and selected noninbred and randomly bred control groups of Rambouillet, Targhee and Columbia ewes. Journal of Animal Science 56: 316–329.CrossRefGoogle ScholarPubMed
Falconer, D. S. 1989. Introduction to quantitative genetics. 3rd ed. Longman, London.Google Scholar
Harvey, W. R. 1977. Users' guide to LSML76. Mixed model least squares and maximum likelihood program. Ohio State University, Columbus.Google Scholar
Lamberson, W. R. and Thomas, D. L. 1984. Effects of inbreeding in sheep: a review. Animal Breeding Abstracts 52: 287–297.Google Scholar
Lee, G. J. 1984. A comparison of carcass traits in Scottish Blackface and Welsh Mountain lambs and their crosses. Animal Production 39: 433–440.Google Scholar
Wiener, G. 1967. A comparison of the body size, fleece weight and maternal performance of five breeds of sheep kept in one environment. Animal Production 9:117–195.Google Scholar
Wiener, G. and Hayter, S. 1974. Body size and conformation in sheep from birth to maturity as affected by breed, crossbreeding, maternal and other factors. Animal Production 19: 47–65.Google Scholar
Wiener, G. and Woolliams, J. A. 1982. The effect of crossbreeding and inbreeding on the performance of three breeds of hill sheep in Scotland. Proceedings of the world congress on sheep and beef cattle breeding, vol. 1. (ed. Barton, R. A. and Smith, W. C.), pp. 175–187. Dunsmore Press Ltd, Palmerston North, New Zealand.Google Scholar
Wiener, G., Woolliams, C. and Slee, J. 1988. A comparison of inbred and outbred sheep on two planes of nutrition. 1. Growth, food intake and wool growth. Animal Production 46: 213–220.Google Scholar
Woolliams, J. A. and Wiener, G. 1981. The effect of breed type and inbreeding on characteristics of the fleece and skin of 12-week-old lambs. Animal Production 32: 9–22.Google Scholar