Cogent recently partnered with the UK Guernsey Cattle Society to genomically test 500 females through PrecisionDNA, its in-house genomic testing service. The main aim was to establish the genetic potential of the current UK Guernsey population while also looking at the prevalence of the A2A2 milk gene of which 99% carried at least one copy.
PrecisionDNA provides the ultimate in female genomic testing for dairy farmers, and the UK Guernsey Cattle Society has benefitted from its many advantages, by evaluating over 40 traits with high reliability.
William Barber, Genetic Testing Specialist, Cogent Breeding says: “Working with the Guernsey Society has allowed us to learn so much more about the genetics of the breed as a whole and identify its strengths and weaknesses in relation to other dairy breeds, “We can now use this to shift focus onto traits in which the breed is weaker when making breeding decisions”.
It also highlighted the high genetic variation within the breed for example, milk which had a variation of over 1,000kg between the animals with the highest and lowest genomic values. Although this could be perceived as a negative, it can also be indicative of the diversity of the gene pool – which in breeds with smaller populations can be significantly beneficial.
Despite this the averages for many of the key health, production and type traits were similar to the predictions already being used by AHDB in their proof calculations, meaning the base animal used as a comparison in linears and health traits was already a very accurate depiction of the average Guernsey cow in the UK.
This is testament to the milk recording and classification data which is gathered from pedigree Guernsey herds, but it can certainly be bolstered and made more reliable by feeding additional data into the database through genomic testing.
Mr Barber says: “The data provided through genomic testing is significantly more reliable than breeding from parent averages alone, genomic data is 40% reliable versus 17% for data derived from parent averages.
“Although improving a breed using accurate data takes years, the implications of bad breeding decision because of poor data spans generations,” he adds.
Currently within the Guernsey breed there are no known haplotypes affecting fertility, but this is not to say there are none. For example, within the Holstein breed six haplotypes, resulting in early embryonic death, have been identified since the bovine genome was sequenced in 2009, which previously would have been attributed to fertility problems when in fact a genetic defect was at work.
Genomic testing has also helped the Ayrshire breed to identify a high prevalence of two particular haplotypes within its population, with a third recently discovered. This means informed breeding decisions can be made to avoid the crossing of two carriers which may have resulted in either the birth of further carriers or the loss of the embryo.
“Haplotypes can have a financial impact and in today’s climate where efficiency is key, no dairy farmer can afford for animals to remain open for a sustained period.”
As the database of genomically tested Guernseys increases, the Society can benefit greatly from a bull procurement perspective by being able to identify genetic outliers for traits in which the breed falls short.
“If the breed has ambition to promote itself outside of the UK, genomics is the only way to do that,” says Mr Barber.
William Astley, Friesian and Coloured Breeds Specialist for Cogent says: “The testing that has been done has helped build a better picture of the genetic potential within the breed which will not just benefit farmers but the future of the breed when choosing females for contract mating.
“This data should ensure genetic gain in the next generation of UK Guernsey sires through more informed decisions on which cows to mate and which sire suits them best. These improvements will not only help improve the UK breed but futureproof it for generations to come.”
Write a comment