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Cow milk has been used globally for its nutritive and medicinal values in all age groups. There are references on cow milk in ancient Vedas. Ayurveda, the Indian system of medicine, has described in detail the innumerable benefits of cow milk. Charaka (200 B.C.), describes the following properties of cow milk:

“Svadu, sheeta, mridu, snigdha, bahula, shlakshna, pichcchil, guru, manda, and prasanna Dashaguna…” “Cow’s milk has 10 properties: sweet, cold, soft, unctuous, dense, smooth, viscous, heavy, slow and pleasing.” It is said to enhance tissues and immune resistance. Many cow products are used for their health promoting, disease-preventing and therapeutic purposes. Besides its nutritive use, milk and milk products are used in conjunction with medicines to enhance their pharmacokinetic and dynamic benefits. In Ayurvedic rejuvenation programmes, milk is central to tissue regeneration. It contains many beneficial proteins, hormones, growth factors, vitamins and minerals.

Cow milk is constituted of Water – 87%, Carbohydrate (Lactose) – 4.8%, Fat – 4%, Protein (Casein, Whey, Glycoprotein) – 3.4%, Minerals (Ca, K, I) – 0.8%, and Vitamins (A, B2, B12). Casein forms about 80% and whey protein forms about 20% of the total protein content in the milk. Glycoproteins are found in trace fractions. Thus, casein becomes a major source for supply of all essential amino acids (except sulphur-containing amino acids – methionine and cysteine).1 Based on the DNA sequence, casein is classified into four types viz, aS1, aS2, ß, ?. Milk contains lactoferrin that is microbicidal. Mother’s milk helps in establishing healthy microbiome of the gastrointestinal tract.

Debate on ß-casein types in Cow’s Milk
ß-casein is a protein with 209 amino acids chain. At its 67 position, the A1 type is a mutant variant which has the amino acid – Histidine instead of Proline in the natural A2 type. This variant was developed due to mutation in normal A2 beta casein gene about 3,000 years ago in Europe. Indian desi cows did not have this mutation. This mutation leads to an enzymic product of the A1 type in the small intestine. A1 casein, unlike A2 type, is prone to digestion by pepsin, leucine aminopeptidase and elastase. A 7 amino acid peptide, called ß casomorphin 7 (BCM-7) is released by the proteases. BCM-7 binds to the opioid receptors and causes immunosuppression – leading to type 1 diabetes mellitus (DM1), cardiovascular diseases (CVD), autism, metabolic syndrome, schizophrenia2 (Fig. 1).

It was in the 1990s that this hypothesis of A1 type of beta casein as a risk factor, was developed by R B Elliot for various diseases. He found that children in Polynesian islands, with an access only to A2 type were at lower risk of Diabetes type 1 than Polynesian children in Auckland who were on A1 type of milk. He further confirmed his hypothesis by in vivo experiments on non-obese diabetic mice. Similarly McLachlan CNS, also in Auckland, found a direct correlation between the mortality rates from coronary heart disease in 16 countries with their national A1 ß-casein consumption (g/day).

Cow Breeds and Types of Milk (A1 or A2)
The type of milk a cow will produce depends on the genotype frequency. Each cow carries two copies of the gene encoding beta-casein with a genotype of A1/A1, A1/A2 or A2/A2. Neither A1 nor A2 trait appears to be dominant. This means that the milk produced by an A1/A2 cow – contain equal proportions of A1 and A2 beta-casein; A1/A1 cows would produce only A1 beta-casein and A2/A2 cows would produce only A2 beta-casein.

The genotype frequencies of different cow breeds are shown in Table 1.

Table 1. Genotype Frequencies of Different Cow Breeds

Indian study by Mishra et al has reported the status of beta casein gene in native Indian cows. From Table 2 it can be seen that, except for Maland Gidda and Kherigarh breeds, all the native cow breeds (Milch as well as non-milch cows) are pure A2 type3. Hence native Indian cows should be pure-bred, chosen, protected and increased in number.

Table 2. Genotype Frequencies of Native Indian Cow Breeds

Global Status of Indian Cow Milk
Exotic European varieties of cattle (Bos taurus species) like Holstein Friesian (from Holland), Jersey, Brown Swiss (from Switzerland), Ayshire (from Scotland), Red Dane (from Denmark) etc. were introduced in India as a measure to improve the milk yielding capacity of indigenous cows4. But these cows contain the A1 variant of beta casein protein, which has been related to all the health conditions (vide supra). Moreover these cows are less heat- tolerant and less disease-resistant as compared to Indian cattle. Indian cows have to be provided proper nutrients and care to enhance the milk yield. This has been demonstrated in the past by several cow-caring organisations in India and by the Gir cows in Brazil.
The demand for Indian cattle (Type 2 milk) is rising in many countries like Australia, Brazil, Africa, South America and Southeast Asia. A news report titled “Climate change spurs positive for India:Overseas demand for indigenous cattle rises” (dated: Nov. 11, 2014) states that Gir and Ongole cows are economically very profitable. Indian exports of embryos of A2 genotypes is a lucrative business. High quality semen of Bazilian Gir bulls is imported for artificial insemination and enhancement of the local high milk-yielding breeds.

India is the No. 1 in milk production in the world—thanks to the white revolution ushered in at Anand by Kurien. But India should be the world leader in providing pure Type A2 variety milch cows and their milk. This could lead to not only a major source of income for the country but also stem the pandemic of diabesity and cancer in India. But the sad plight is that Gujarat has around 3,000 pure breed Gir cows left and Brazil has emerged as the world’s biggest supplier of improved cattle embryos and semen of Indian origin. The Government of India and the stakeholders need a dynamic strategy to address the problem.

Future Scope and Direction
It cannot be overemphasised that there is an urgent need to expand the Indian breeds of the cows. An awareness campaign has to be launched about the risks with the A1 type of milk. The cross breeding native Indian cows with the European breeds of cows has to be curbed.

The ways to increase the milk productivity of Indian cow breeds, shown earlier, should be revived. The British rulers and merchants exported Indian cattle breeds to their other imperial colonies almost  a century ago. It is now a well-documented fact that the milk productivity of those cows is approximately three times more than that of the average of Indian cows present in India.

Looking at the health risks associated with the A1 type of milk, the nutra and the dairy industry should first analyse the raw materials for the milk products for the A1 or A2 type of milk. Regulations can be considered to permit only A2 type milk. Simple tests must be evolved for the detection of A1 and A2 ß casein in India. In addition, research has to explore the nature of milk allergies and milk antigens. Our group has proposed a project of robust lacto-epidemiological studies to correlate the prevalence of A1 casein related metabolic and other disorders.

Acknowledgements
Bombay Gorakshak Trust and Dr Rama Vaidya

References
1. III-Dairy-E-Casein-3; Available at http://nzic.org.nz/ChemProcesses/dairy/3E.pdf ; Last accessed on 22nd Feb 2015
2. A.F. Keating, T.J. Smith, R.P. Ross and M.T. Cairns. A note on the evaluation of a beta-casein variant in bovine breeds by allele-specific PCR and relevance to ß-casomorphin. Irish Journal of Agricultural and Food Research 47: 99–104, 2008
3. Mishra et al. Status of milk protein, ß-casein variants among India milch animals, Indian J. Animal Sciences, 2009;79(7):722 – 725.
4. Henna Hamadani et al , Breeds of cattle and buffalo in India, Available at http://en.engormix.com/MA-dairy-cattle/genetic/articles/breeds-cattle-buffalo-india-t2420/103-p0.htm ; Last accessed on 23rd Feb  2015

(De is junior research fellow,  Paradkar is senior research fellow, and Vaidya is research director at Medical Research Centre, Kasturba Health Society, Mumbai. They can be reached at supde2003@gmail.com, prajakta.hsp@gmail.comand ashokdbv@gmail.comrespectively)

 

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