Last October, the government announced a major initiative to improve the milk productivity of Indian cows. The Department of Biotechnology (DBT) said it would embark on a year-long project to map and analyse the genomes of at least 40 local breeds of cattle. India is the world’s largest producer of milk, partly due to importing European cows and cross-breeding them with local varieties as well as having a successful decades-long programme to source milk from small farmers through cooperatives. However, milk productivity in India, which ranges from 2-4 kg a day, is much lower than the 25-38 kg a day yielded by cattle in the United States, Europe or Israel.
DBT officials told The Hindu that the National Institute of Animal Biotechnology in Hyderabad — a DBT-funded organisation — would sequence the genetic structure of several strains of cattle and then take steps to ensure that these cattle were bred and popularised.
Focus on local breeds
One reason for heightened interest in the milk of local breeds is a raft of research that implicates a protein — called A1 beta-casein and found in the milk of several European breeds — being linked to a risk of diabetes, ischemic disease and heart disease. Cattle that lack the A1 gene are categorised as A2.
A1 and A2 beta-casein are genetic variants of the beta-casein milk protein that differ by a single amino acid. The A1 beta-casein type is the most common type found in cow’s milk in Europe (excluding France), the U.S., Australia and New Zealand. A controversial company, called the A2 Corporation (and now renamed the A2 Milk Company), patented and marketed a test that purportedly checked if a cow was likely to give A2 or A1-laced milk.
While commercial breeds in India are dominantly A1, there are several indigenous breeds that may have the safer A2 genes that lead to milk free of A1 proteins.
However, scientists now say that techniques are round the corner that can potentially ‘silence’ A1 genes. Genome editing software such as CRISPR-Cas9 can be used to achieve this. Dr. Bruce Whitelaw’s group from the Roslin Institute (University of Edinburgh), and Dr. Satish Kumar, chief scientist at the Centre for Cellular and Molecular Biology, Hyderabad, have recently published a review on some of the solutions that researchers have developed over the years using tools of genetic engineering. “A key development has been our ability to introduce the necessary genes into the local breeds, without the necessity to cross-breed, which is relatively more uncontrolled,” Dr. Kumar told Research Matters .
Improving milk
Another instance where genes could be tweaked to improve milk, according to Dr. Kumar, is to remove sources of allergies from milk. Beta-lactoglobulin is a protein in cow’s milk that triggers an allergic reaction in many infants. However, in 2014, a group of researchers at the University of Vienna discovered that it was the absence of iron in beta-lactoglobulin which led to allergies. That means that if there were ways to set off another set of genes to produce iron, cow’s milk would be palatable to many more children.
Genes could also be tweaked to increase the protein content of milk and tinker with their structure to make them last longer without spoiling and be more resistant to bacterial degradation.
jacob.koshy@thehindu.co.in
