Conservation of rare wild-living cattle Bos taurus (L.): coat colour gene illuminates breed history, and associated reproductive anomalies have not reduced herd fertility

Coat colour patterns are important characteristics of many cattle breeds and in some are determined by a chromosomal translocation, which can have the pleiotropic effect of testicular hypoplasia. We test the hypothesis that this variant, known as the Cs-29 allele, is prevalent in the ancient Chillingham White Cattle (Bos taurus) of north-east England. Its distribution may provide insights into breed history, and as it is associated with reproductive anomalies, we investigated the issues of subfertility in this cattle herd which are of clear relevance to its conservation. We report that the cattle are homozygous for the translocation. As it is also known in other breeds of the England-Scotland border and northern Irish area, namely the White Galloway and Irish Moiled, and in the Northern Finncattle and Swedish Mountain, we further hypothesize a Scandinavian connection for White Galloway, Irish Moiled and Chillingham cattle. We present unpublished data showing testicular hypoplasia to be present at Chillingham. Sperm quality is also known to be very low, and the question arises as to how the highly inbred (F-is = 0.92) Chillingham cattle have continued to survive in spite of these reproductive anomalies. Surprisingly, herd fertility has not declined over the last 160 years, and in the light of behavioural data, we propose this is probably because of multiple mating, there being no castration and only welfare culling in this herd. These findings have wide relevance, particularly for breeds of conservation importance and probably for other bovine species, because male subfertility, frequent in cattle generally, could restrict the choice of bulls for representation in gene banks with consequent risk of loss of lineages. Research on heterospermic insemination or multiple mating of cattle could, therefore, be a useful complement to the development of assisted reproduction technologies for cryoconservation.

Automated summary

The Chillingham White Cattle carry the Cs-29 allele as a homozygous translocation, similar to other breeds in the England-Scotland border and northern Irish area, suggesting a possible Scandinavian connection. Despite testicular hypoplasia present in Chillingham cattle, herd fertility has not declined over the years, possibly due to multiple mating and welfare culling practices.