Guernsey milk samples have tested as 95% Beta Casein A2 which is the desired type of Casein (A2 is not linked to any possible health problems), but there are bloodlines within the breed that carry the A1 Casein. We have identified 14 modern bulls that carry A1 and 12 of these trace to Welcome Choice Admiral and the 2 bulls that are Homozygous A1  (A1xA1) have Admiral blood on both sides of the pedigree.

These bulls CC Enhancer Storm and Jacob of the Bigard will be withdrawn from service, their progeny will be at best Heterozygous (A1x A2) but if used onto a Heterozygous Dam could combine as either (A1x A1) or (A1x A2).

EGCS Council have decided that potential Bull mothers should now be tested, so that in future we can be sure that only bulls that are (A2 x A2) are used in AI, this will involve between 30 and 40 cows a year for the next 2 or 3 years, but we should then be able to move to their daughters which once we know the Genotypes of their Parents we can safely predict their Genotypes.

I tabled a worst case scenario to Council looking at the possible Genotypes of the top 50 cows on GMI and the top 50 Heifers and approximately 30% could be expected to be (A2xA2) and 30% (A1xA2) with perhaps 5% (A1xA1)  and 35% with one Parent as yet of an unknown status. This is why we must test so as to provide certainty, it would not be fair to ask a member to rear a bull calf, only to reject him if he carries the A1 Genotype.

All imported semen and those UK young bulls already born that are of the necessary GMI standard for AI use will now be DNA tested (using hair samples) and only those that are (A2xA2 ) will be offered for use. Please ask your AI providers for information on the bulls they are selling:  if not already tested we will be happy to test them.

The case for A2 is still being investigated but each new study does reinforce the argument for its benefits and we have a unique opportunity to become the only significant Dairy Breed to have majority A2 status and if we work together we can quickly suppress the A1 variant. If you consistently use Homozygous Sires (A2xA2), then no more (A1xA1) sires will be produced and in time the Heterozygous combination (A1xA2) will become less numerous.

To visit the website of the A2 Corporation in New Zealand, please click here.  It should be noted that The English Guernsey Cattle Society has no connection with A2 Corporation and provides this link purely for informational purposes and without endorsement.