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Overview of Cow Milk Protein

Miniature-Cattle.com Mini Milk Maids (miniature dairy cattle) A1 A2 Beta-Casein

Milk is one of nature's most perfect foods, thanks to its combination of essential vitamins, minerals, proteins, healthy fats and milk sugars. And it is fairly well established that when clean cow's milk is raw and from healthy 100% grass-fed cows, its enzymes and probiotics also aid digestion and the effective absorption of nutrients.

Blue Albion cowCows Milk Basic Makeup:
85% water
4.6 % lactose (milk sugar)
3.7 % triacylglycerols (milk fat)
2.8% proteins
0.54% minerals and 3.36% miscellaneous

Cows milk contains six proteins: 2 whey proteins and 4 casein proteins (the caseins make up the majority). Beta casein makes up a third of the casein proteins, and in volume is equivalent to about 1 teaspoon per 2 cups of milk.

Whey proteins make up about 20% of the total protein in cows milk.(5)
Alpha-lactalbumin (ALA) protein makes up about 5% of the total protein milk.
Beta-lactoglobulin (ß-lg) is the major whey protein gene in cows milk (BLG does not occur in human breast milk). It occurs in a number of genetic variants, but the most prevalent bovine variants are BLG A and BLG B. The A variant is associated with higher milk yield and higher whey protein content. The B variant is associated with increased casein and fat content and is favorable for cheese production.

Casein proteins make up about 80% of the total protein in cows milk.
Alpha-casein
Beta-casein (A2)
The 2 most common Beta-casein variants in cows milk are A1 and A2. The A1-beta casein is in general, a more inflammatory casein. The A2/A2 genotype is also considered to have positive effects on human health. The A2 variant has been shown to have a positive association with milk yield and protein content.
Kappa-casein - The 2 most common Kappa-casein variants are A and B. The A variant and AA genotype are associated with higher milk production. The B variant and BB genotype are associated with increased milk protein and casein content, and better cheese yield.

A1 & A2 ßeta-Casein in Cows Milk

There are 2 groups of amino acid variants in the Beta (ß)-casein protein in cow's milk; group A1 and group A2.
Variants that belong to A1 and A2 groups are:

A1 group variants: (His67) are A1, B, C, F and G.

A2 group variants: (Pro67) are A2, A3, H1, H2, I, J, K and L.

There is some evidence that lactose-intolerant people can drink A2 milk without problems. "Breeders interested in developing dairy or dual purpose herds of cattle for human health benefits can use a simple DNA test to determine a cow's beta casein (A1 or A2 group) type."(1)

Lactose sensitivity or intolerance is not the same thing as an allergy. Cow's milk protein allergy (CMPA) is an immune-mediated allergic response to naturally-occurring milk proteins, either or both casein and whey. People who are allergic to milk are still allergic to A2 milk.

The A1 A2 concern is regarding an opioid, ßeta-casomorphine-7 (BCM-7) present in A1 cow milk. According to the growing A2 commercial industry (not wholly objective, mind you), BCM-7 in A1 milk is what causes problems. It is an exogenous opioid (not found in the human body) that interacts with the human digestive system, internal organs, and brainstem. While no direct causal relationships have been demonstrated between BCM-7 and these diseases due to a wide range of contributing factors for each illness, BCM-7 could be linked to type 1 diabetes, heart disease, autism, and other serious non-communicable diseases.(2)

History: Humans, goats and most other mammals produce only A2 milk. Originally all cow milk was of the A2 type. However, a genetic mutation that is believed to have occurred from 5000-10,000 years ago, apparently in the northern European Holstein Friesian dairy ancestors, changed the ßeta-casein they produced. The gene encoding beta-casein was switched from proline to histidine. The original ßeta-casien was A2. The newer mutated ßeta-casein is A1.

The mutation in the beta casein gene eventually led to 12 genetic variants, of which A1 and A2 are most common. The mutation was passed on to many other breeds, principally because Holsteins were used to genetically improve the milk production of other breeds. Slowly, the A1 ßeta-casein variant grew in many breeds. The A1 ßeta-casein mutation is not present in the milk of pure Asian and African origin breeds of cattle. Dairy herds in much of Asia, Africa, and part of Southern Europe remain naturally high in cows producing A2 milk. The A1 version of the protein is more common among cattle in the Western world. (4) The proportion of A1 ßeta-casein is higher in the black and white European dairy breeds compared to the red (yellow and brown) breeds. The Holstein carries A1 and A2 alleles usually in equal proportion, with some sources reporting A1 averaging as high as 65% of the population. The Brown Swiss, Ayrshire and British Shorthorns typically average 35-50% A1. Jersey cows and other southern European breeds probably have about 33% A1 and 66% A2 genetics. Guernsey cows generally have about 10% A1 and 90% A2 genetics. Most European breeds have both variants, but beef cattle breeds generally test a lower incidence of A1 than dairy cattle. (3)

If a cow carries only one copy of the A1 mutation, she produces A1 milk. Therefore, whether a cow has one or both copies of A1, will not affect how her milk is classified. It does provide genetic information for anyone who is breeding away from the A1 mutation, however.

As an example, here are the results of tested Dexter cows at VetGen, UC Davis:
Of 78 cows tested:
A1: 39.1% (these would include both A1/A2 and A1/A1 tested cows)
A2: 60.9% (these would be all the cows that tested A2/A2) (1)

 


sources:

(1) Beta Casein – A2 Genotyping cow's milk. UC Davis Veterinary Genetics Lab

(2) (Ng-Kwai-Hang and Grosclaude 2002), Keith Woodford Professor of Farm Management and Agribusiness Lincoln University New Zealand.

(3) nodpa.com, prepared by Marguerita B. Cattell, DVM, MS, Diplomate, ABVP-Dairy & Arden J. Nelson, DVM, Diplomate, ABVP-Dairy for Windsor Dairy, LLC, Windsor Dairy, LLC owners: Dr. Meg Cattell & Dr. Arden Nelson.

(4) Gonca Pasin, Ph.D., California Dairy Research Foundation

(5) sigmaaldrich.com


publisher: Vintage Publishers
owner: Miniature-Cattle.com
published online: October 2018
author: by Donna G Vickery

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