What is a breed? - Serena Sykes tells all

NORMALLY A small animal vet, I recently developed an interest in genomic research in pedigree dogs and cattle. A report has just been published by Aberystwyth University (IBERS) which I believe is important. It is probably the most detailed DNA investigation yet in any beef cattle breed, and concerns the Hereford, although the methods are applicable to other breeds of livestock.

I first qualified in the 1970s, working in large animal practice in south west Scotland. The farm livestock then were mainly British native breeds. I don’t remember any continental beef cattle or sheep, though some had been imported. All our hardy breeds had their own special characteristics and function making them unique eg the white face of the Hereford, a double dominant gene, which stamped its identity on every calf.

By the 1980s, nutritionists decided that saturated fat in meat was harmful (ironically now refuted). Farmers wanted larger framed, leaner, more muscular animals to produce what the market demanded. The continental breeds became popular and many of the native breeds might have disappeared altogether if it was not for the formation of the Rare Breed Survival Trust (RBST). Farmers who kept native breeds faced the problem of how to make them more “continental”.

Meanwhile, in the harsh environments of the Americas, Australia and South Africa, British native cattle, exported years before, were still proving that they could survive and adapt.

North America was already producing what British breeders wanted. A trickle of importations became a flood when semen and embryos could be imported. This led to a situation which persists today – some of our present '

British' breeds consist almost entirely of imported bloodlines, mainly from North America.

Certain native breed societies made the collective decision to 'open' their herd books, introducing continental bloodlines, eg Limousin and Maine Anjou. Others registered imported animals without question. The result is that some native breeds have both 'Modified' and 'Original' Populations (ie without imported bloodlines) eg the Hereford, Angus, Lincoln Red, Sussex and Dairy Shorthorn. These Original Population cattle are classed by the RBST as 'rare', some 'critically endangered'.

Fast forward to 2013 and suddenly the news was full of 'horse meat being sold as beef'. DEFRA and the Food Standards Agency were already researching DNA profiling of meat products, not only to see if it contained horse, cow or pig, but from which breeds it originated, because labelling and sale of meat by breed of origin is widely used in the retail industry. In 2012, Dr Robert Ogden, now director of conservation science at Edinburgh University, (DEFRA reports Q01130, FA0112 and FA0125) identified a problem with breed assignment of meat samples from the Hereford, which originated from both Modified and Traditional (OP) cattle – their DNA profiles were completely different.

Other geneticists confirmed this initial research, and the new report by Dr Matt Hegarty, Zoe Broadbent and Dr R McMahon (2020) clearly demonstrates that the 'Hereford' is two different breeds, the HOP (Hereford Original Population) and the NADH (North American Derived Hereford).

This is perhaps not surprising, considering the origins of the two populations, but the differences are too great to be explained by 'genetic drift' and suggest introgression of other breeds into the NADH.

In addition, some widely used bulls do not match either population. The HOP is recognised in the herd book by an asterisk(*) but HOPs were widely crossed with NADHs in the past. It is likely that similar results would be obtained in other breeds with both modern and original populations, but this research remains to be carried out.

So do 'breeds' matter, or are they just a Victorian invention? The purpose of the project, to develop a genetic test to identify previously unknown lines of HOP cattle to expand the gene pool, has undoubtedly been achieved.

However, in my opinion, DNA analysis is the future – most breed societies at present only require determination of parentage and genetic abnormalities, but breed assignment for meat provenance is arguably more important for traceability and for consumer confidence, and to detect fraudulent practices. Estimated Breeding Values are of limited value in unrelated animals. There may be infringements of Zootechnical regulations.

Most importantly, for UK livestock breeding, this study showed that 63 SNP markers which strongly differentiated the HOP from the NAD, while mainly linked to body mass and milk composition, also showed involvement with meat tenderness, marbling, fertility, feed efficiency, immune response and disease resistance.

Genetic diversity may be very important to UK farmers in the future with Brexit, agricultural support reduction and increased demand for meat from sustainable low-quality grazing systems. I believe this should be protected and promoted.

A link to the paper can be found here - hdl.handle.net/2160/7ae993bf-83d8-47da-a2a3-768cae47744b