A1 or A2 milk in Jerseys?

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I received a question about the possibility of A1 or A2 milk in Jersey cattle from Mr. . With his permission I am posting my reply on the RawDairy forum, since I think it will be of interest to many.

> Gene Bowen>> thank you for your information, and for your efforts to advance > understanding of A2 milk>> have you any guesses about antique mini-Jerseys being A2?>> Gordon

Mr. ,The only way to tell is to have a DNA test done. There are no visible indicators. The milk tastes and feels the same.Jerseys are very similar in genetic makeup to all the other British breeds. So much so that there isn't yet a definitive DNA test for breed. In other words, they still can't tell a Jersey from a Guernsey by DNA. They're that similar.Therefore, it is my guess that Jerseys are no more or less likely to carry the A1 gene than any other dairy breed.Among the published results from the breeds tested so far, It appears that the A1 is most prevalent in the Holstein-Friesian breed. Yet it was found in my herd of US Dexters, a very primitive breed. The American Dexter Cattle Association has never allowed outcrossing of any of it's registered cattle. Yet the A1 gene was found in two of my cows. If it didn't get there from an outcrossing, it must be native to the breed.American Jerseys have allowed outcrossing. Only the cattle born and raised on the Isle of Jersey in the last two centuries were not allowed to be outcrossed. The original Jersey cattle imported to this country were from that stock. They were all horned. Every one. The color black was almost nonexistent in their coat. An early breeder used Angus genetics to create a line of polled Jerseys, which were very popular and spread widely. That's one case of outcrossing, where the A1 could have gotten in, even if it wasn't there before. That outcrossing also introduced the black markings that are on so many jerseys today.The original Jerseys were small, probably no taller that 45" or 46". The "mini" Jerseys of today are a mixed lot. Some were bred down in size using Dexters. Others were selected for size until their height was reduced. Records of this are hard to come by. It's nearly impossible to tell which you are getting today.Standard sized Jerseys were frequently crossed with Holstein-Friesians to increase their milk production. It was a common practice among Jersey dairy herds. The offspring of these herds were sold as Jerseys. Even though they were part Holstein, the most common source of A1.All of this is to establish the fact that the American Jersey as a breed isn't 100% pure. It contains genetics from other sources, including sources known to contain A1. So even if you were to assume that the Jerseys didn't have A1 originally (which I don't believe), then it would be hard to assume that they were free of it now.I know that one Jersey bull was in the batch when my cattle were tested. There could have been more. The results were coded by ID numbers, and I only got the Id numbers for mine, so I can't tell you how the Jersey bull tested.It is my belief that Jerseys are probably right in there with all the other dairy breeds in having A1 milk genes. I read that 40% to 50% of all dairy cattle do not have the A1 gene, and therefore produce A2 milk. That figure is as low as 30% for Holsteins, so some of the dairy breeds must be better than 50%. Whether Jerseys are better or worse is anybody's guess, until they are properly tested.GeneboParadise Farm