OMIA 000443-9940 : Halo hair 1 in Ovis aries

Mendelian trait/disorder: yes

Considered a defect: yes

Key variant known: no

Species-specific name: Carpet wool

Species-specific symbol: N

Species-specific description: Normal wool fibres are solid. In contrast, hair has a core (medulla) down the centre, filled with air. Sheep that are bred for wool have almost zero medullated (hairy) fibres. In 1931, a purebred Romney Marsh ram lamb with an exceptionally hairy fleece was born in New Zealand, on a property belong to a Mr Nielson. The lamb was given to Professor Dry at what is now Massey University, where a set of experimental matings showed that the extreme hairiness is due to an incompletely dominant allele, N, at an autosomal locus (Dry et al., 1940; Dry, 1955). NN homozygotes have approximately 65% by weight of medullated fibres. This is no use for traditional wool production, but it is ideal for carpet manufacture. In the following decades, the mutant allele was multiplied within a Romney background, giving rise to a new 'carpet-wool' breed: the Drysdale. Other carpet-wool alleles have appeared from time to time in New Zealand and Australia, also eventually giving rise to new breeds: the Tukidale and the Carpetmaster in New Zealand, and the Elliotdale in Tasmania. The New Zealand mutants appear to be alleles at a single locus, but there is some evidence that the Tasmanian mutation is at a different locus (Sides and Banks, 1987). The most comprehensive review of carpet-wool genetics is provided by Wickham (1978).

References


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
1987 Sides, R.H., Banks, R.G. :
The genetics of carpet wool production: the Elliotdale breed :356-359, 1987.
1981 Alston, B.T., Edey, T.N. :
An accelerated progeny test method for Tukidale rams using controlled reproduction techniques Wool Technology and Sheep Breeding 29:134-136, 1981.
1978 Wickham, G.A. :
Development of breeds for carpet wool production in New Zealand World Review of Animal Production 14:5, 7, 33-40, 1978.
1969 Rae, A.L. :
The Drysdale sheep: its history and present development Sheepfarming Annual 1969 :69-76, 1969.
1963 Cockrem, F. :
Body growth and fleece development in the New Zealand Romney N-type sheep Animal Breeding Abstracts 31:445-453, 1963.
1959 Carter, H.B., Tibbits, J.P :
Post-natal growth changes in the skin follicle population of the New Zealand Romney and N-type sheep Journal of Agricultural Science 52:106-116, 1959.
Cockrem, F. :
Studies of the effects of the gene N on body growth and fleece development of the New Zealand Romney. II. The development of the fibre population Australian Journal of Agricultural Research 10:400-412, 1959.
Cockrem, F. :
Studies of the effects of the gene N on the body growth and fleece development of the New Zealand Romney sheep. III. Fibre diameter and medullation Australian Journal of Agricultural Research 10:413-423, 1959.
Stephenson, S.K. :
Wool follicle development in the New Zealand Romney and N-type sheep. IV. Pre-natal growth and changes in body proportions Australian Journal of Agricultural Research 10:433-452, 1959.
Stephenson, S.K. :
Wool follicle development in the New Zealand Romney and N-type sheep. V. The pre-natal relationships between growth, skin expansion, and primary follicle number Australian Journal of Agricultural Research 10:453-470, 1959.
Stephenson, S.K. :
Wool follicle development in New Zealand Romney and N-type sheep. III. The diameters of follicles and fibres Australian Journal of Agricultural Research 10:108-120, 1959.
Tibbits, J.P. :
Post-natal growth changes in the fibre cortex and medulla of the New Zealand Romney and N-type sheep. Journal of Agricultural Science 53:358-368, 1959.
1958 Dry, F.W. :
Further breeding experiments with New Zealand Romney N-type sheep to 1956 Australian Journal of Agricultural Research 9:348-362, 1958.
Stephenson, S.K. :
Wool follicle development in the New Zealand Romney and N-type sheep. II. Follicle population density during fetal development Australian Journal of Agricultural Research 9:138-160, 1958.
1957 Stephenson, S.K. :
Wool follicle development in the New Zealand romney and N-type sheep. I. The relationships of development to age in the New Zealand romney and N-type sheep foetuses and a comparison with results obtained from the merino Australian Journal of Agricultural Research 8:371-384, 1957.
1956 Stephenson, S.K. :
Some aspects of gene dosage in N-type sheep Australian Journal of Agricultural Research 7:447-468, 1956.
1955 Dry, F.W. :
The dominant N gene in New Zealand Romney sheep Australian Journal of Agricultural Research 6:725-769, 1955.
1954 Fraser, A.S., Ross, J.M, Wright, G.M. :
Development of the fibre population in N-type sheep Australian Journal of Agricultural Research 5:490-502, 1954.
Ross, J.M. :
Development of the follicle population in N-type sheep Australian Journal of Agricultural Research 5:484-489, 1954.
Ross, J.M., Wright, G.M. :
Kemp succession in N-type sheep Australian Journal of Agricultural Research 5:503-, 1954.
1952 Dry, F.W. :
The genetics and fibre morphology of N-type sheep. New Zealand Science Review 5:69-71, 1952.
1950 Dry, F.W., Fraser, A.S. :
The genetics of N-type sheep Heredity 4:137 only, 1950.
1946 Dry, F.W. :
Breeding N-type sheep. Proceedings of the New Zealand Society of Animal Production 1946 :95-97, 1946.
1940 Dry, F.W., McMahon, P.R., Sutherland, J.A. :
A Mendelian situation in the birthcoat of the New Zealand Romney lamb Nature 145:390-391, 1940.

Edit History


  • Created by Frank Nicholas on 06 Sep 2005
  • Changed by Frank Nicholas on 18 Oct 2011
  • Changed by Frank Nicholas on 21 May 2012