Summary of Article About Dexters

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"A Comparative Study of Blood Groups in the Kerry and Dexter Cattle Breeds" 
by C. Buys and Jy Chiperzak

A chapter in the book, Genetic Conservation of Domestic Livestock, Volume 2, 1992, edited by Lawrence Alderson and Imre Bodό, published by CAB International, Wallingford, UK, pages 247-250. The book brings together a number of papers presented at the second non-governmental meeting on the genetic conservation of domestic livestock, held in Budapest in August 1991. This was also the first conference of the newly established Rare Breeds International.

At the time of publication, C. Buys was at the Stichting Gezondheidsdienst. Voor Dieren in Gelderland (in the Netherlands) and Jy Chiperzak was from the Joywind Farm Rare Breeds Conservancy (which later became Rare Breeds Canada - www.rarebreedscanada.ca).

Introduction (Pages 247-248)
 

The authors note that livestock history books tend to view the Dexter breed as a special line derived from the Kerry breed. They quote Felius (1985) as writing that "the Dexter (first reported in 1776) may be a mutation selected from the Kerry or may have resulted from later breeding with it" while Sambraus (1986) noted that "the Dexter can be considered as a dwarf form of the Kerry. At the end of the eighteenth century Mr Dexter, living in the southwest of Ireland, wanted to breed a small dual-purpose cow. He mated a small cow with short legs and a large udder to a Kerry bull. The offspring formed the basis of the Dexter breed."

The authors believe that the Kerry breed is probably a very ancient one, dating back to when cattle from Spain, mainly of Hamitic Longhorn type, spread over western Europe early in the second millennium BC. However, numbers of both the Kerry and Dexter are currently very low, both having been close to extinction. The Kerry remains quite rare.

Kerry cow, Castlelough Flora, at the

Royal Ulster Show in 1951 (page 249)

"In the Dexter, a high percentage of defective 'bulldog' calves are found and this is one reason why the Royal Dublin Society wishes to reintroduce Dexters to Ireland using an earlier system of breeding short-legged Dexter females to Kerry bulls in order to avoid this problem. The international breed societies are disturbed by this proposal. Since 1919 the Kerry and Dexter have been maintained as separate breeds and bred for different physical traits. They are now quite different from each other and to bring them back together would confuse the situation internationally, and might put the breeds at risk" (pages 247-248). The authors believe it would be useful to develop guidelines to define the basic similarities and differences between the two breeds, and they note that blood typing is a helpful tool for this.

Courmouse of Knotting, a very small Dexter cow

bred by Miss Jayne Paynter (page 248)

Blood Typing (Page 248)

The authors point out that blood groups are genetically controlled substances on the surfaces of red blood cells. "At present, 11 loci are known on the chromosomes of cattle which determine the blood groups. A blood group system is the collection of blood groups determined by the alleles of one locus. In some systems, such as B, C, and S, many groups are known. Due to the wide genetic variation in blood groups the probability of finding two unrelated animals with an identical blood type is very small. A blood group consists of one or more factors. In each blood group system an individual has a group derived from the sire and one from the dam" (page 248). It is possible to determine the gene frequencies of blood groups per system within a breed. Comparisons of these gene frequencies are able to indicate the degree to which the breeds are related.
 

Materials and Results (Page 249)

The authors made a comparison in blood group frequencies between 45 Kerries and 45 Dexters. The Kerry blood types were from animals typed in Ireland in the 1970s and from Canada in the 1980s. The Dexter blood types were from animals in Canada, England and the USA collected in the 1980s. In these populations, the frequencies of the groups in the B and C systems were determined as shown in the Table below (Table 25.1, page 250). The results showed significant differences between the two cattle breeds. In the second Table below, (Table 25.2, page 250), the frequencies of blood groups in seven systems are examined. One of the points of interest to the authors was that in the S system, the factor U′ is found frequently in the Kerry but not at all in the Dexter.

Table 25.1: Blood group frequencies (in %) in the B and C systems.

Table 25.2: Frequencies of blood group factors in seven systems.

Conclusion (Page 249)

"Blood group studies in populations of Kerry and Dexter cattle demonstrate significant differences in gene frequencies. This indicates that Kerry and Dexter cattle should be considered as separate breeds" (page 249).

References (Page 250)

Alderson, L. (1989). The Chance to Survive. A.H. Jolly (Editorial) Limited and Rare Breeds Survival Trust.
 

Felius, M. (1985). Genus Bos: Cattle Breeds of the World. MSD AGVET, New Jersey.

Sambraus, H.H. (1986). Atlas der Nutz Tierrassen. Eugen Ulmer, Stuttgart.
 

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