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4) Research on Dexters 

There is limited material on the Internet about scientific, social and historical research on Dexters or related to Dexters. The following are amongst the more useful.

A) GENETIC RESEARCH

1. Introductory Material

i) "Mendelian Inheritance and Beyond" - http://skyway.usask.ca/~schmutz/Mendelian.html - an outstanding explanation of a range of genetic inheritance processes beyond the very simple ones. A paper of general interest but three examples are of relevance to Dexter breeders - first, the short-legged gene is an example of "Autosomal Dominant Inheritance" (where a single copy of an allele is enough for a trait to be expressed - note: a gene consists of two alleles, one inherited from the mother, the other from the father); secondly, where the death of the animal occurs when it is a homozygous carrier of that particular gene, that is, when the animal has two identical alleles, as is the case with the Dexter bulldog calf, this is a "Homozygous Lethal" trait; thirdly, the dun gene in Dexters is an example of "Gene Interaction", where specific alleles at two or more locations are required for a trait to be expressed (for cattle to be dun, they must have at least one allele at one gene to produce a particular pigment and then to be homozygous - have two identical alleles - at another gene).

ii) "Genetic Terms" by Gabriella Nanci - http://bellefourchedexters.tripod.com/Articles/Genetic Terms.htm - a useful list of definitions of a number of technical genetic terms, provided by a Dexter breeder.

2. Useful Advanced Genetic Material

Sheila Schmutz is a Professor of Genetics in the Department of Animal and Poultry Science at the University of Saskatchewan. She has developed web-based material on cattle genetic research that she and her colleagues have conducted , including on coat colour and polledness, to be found at http://skyway.usask.ca/~schmutz. She has also written "Genes for Cowboys"  http://skyway.usask.ca/~schmutz/Cowboys.html, a summary of what is known about inheritance patterns and a range of cattle traits.

3. On Dwarfism in Dexters and the Chondrodysplasia Gene

In 2002, a paper was presented at the Second World Dexter Congress announcing the identification of the gene causing chondrodysplasia in Dexters (a summary of this paper is provided elsewhere in Dex-Info - see here). Early scientific papers on the bulldog calf problem in Dexters were written by F.A.E. Crew, Animal Breeding Research Department, University of Edinburh. These included "The significance of an Achondroplasia-like Condition met with in Cattle" in Proceedings of the Royal Society, Series B, vol 95, 1923, pages 228-255, and "The bull-dog calf: A contribution to the study of acondroplasia" in Proceedings of the Royal Society of Medicine (Comparative Medicine), vol 17, 1924, pages 39-58. It appears that little more was published on genetic studies until the late 1990s. The following can be found on the Internet, some only by subscription or payment.

i) "Dwarfism in Dexter cattle is not caused by the mutations in FGFR3 responsible for achondroplasia in humans" by A.P. Usha, D.H. Lester and J. L. Williams, Animal Genetics, vol 28 no. 1, 1997, pages 55-57 - Abstract available at www.blackwell-synergy.com/links/doi/10.1111/j.1365-2052.1997.00068.x/abs - you have to pay a fee to get a copy of the full article unless you are a member of an institution or company that subscribes to to Blackwell's on-line service. This paper, written by scientists from the Roslin Institute in Scotland, notes that the genetic defect causing dwarfism in Dexters has been likened to achondroplastic dwarfism in humans (e.g., in Crew's work). Recent research had discovered that the human condition was the result of a mutation in a particular region of a certain gene. The paper reports on the analysis of that genetic region in normal (non-short) Dexter cattle and in bulldog calves. Unexpectedly, the researchers found that the gene was the same in both, and was therefore not the one causing Dexter dwarfism.

ii) "Chondrodysplasia in Australian Dexter cattle" by P.A.W. Harper, M.R. Latter, F.W. Nicholas, R.W. Cook and P.A. Gill, Australian Veterinary Journal, vol 76 no. 3, 1998, pages 199-202 - www.ava.com.au/avj/9803/98030199.pdf - if this does not work, go to www.ava.com.au, click on "Media and Publications", click on "Select a Section" in the grey "Publications" box and choose ""Australian Veterinary Journal", then click on "Past Issues", on the next page click on "AVJ 1998", choose the "March 1998 issue", and in the "Original Artilces" section , look for the article "Chondrodysplasia in Australian Dexter cattle" - you should be able to download a pdf copy (as long as you have Adobe Acrobat and are patient).

iii) A paper was presented at the Second World Dexter Congress

Iron Age farm one?????

4. On the Dun Gene in Dexters

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