Beta-casein typically compromises about 30% of total protein in cows’ milk. Owing to genetic variation it may be present in milk as one of many variants in modern cattle; with A1, A2, A3, B, C and I the most prevalent variants in
Western dairy herds.
Beta-casein variants differ from one another by virtue of amino acid sequence, this has an impact on the structure that the protein adopts and subsequently the way it is digested. One amino acid difference at position 67 of the protein allows the preferential production of a protein fragment termed BCM-7 from the A1 and related variants, but not A2 nor variants that share a common structure at this part of the protein. On this basis beta-casein can be generally divided into either A1-type or A2-type.
The A1-type of beta-casein has been linked to intolerance type responses and its exclusion from milk may allow people who have previously limited dairy intake to benefit from the nutritional goodness it offers.
Further information relating to research on beta-casein variants and bioactive fragments generated from their digestion can be found at www.betacasein.net. CRV Ambreed can test your current herd for A2 status via our DNA Parentage testing or Herd Testing.
CRV has the ability to analyse Herd Test milk samples for beta-casein types. This can be bulk milk, or per animal.
This will result in a cow being classified into one of three categories;
1. A2/A2: This phenotype will result in only A2 type beta-casein in the milk.
2. A1/A2: This phenotype will result in an equal amount of A1 and A2 type beta-casein in the milk.
3. A1/A1: This will result in an onlyA1 type beta-casein in the milk.
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CRV can provide beta-casein status from tissue DNA samples.
Gene Mapping identifies the sire and dam as well as the A2 type beta casein status.
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