Increasing evidence supporting the correlation between bovine beta-casein and disorders in milk consumers has led to the development and popularity of A2 milk and milk products worldwide. [2] The indigenous cattle population of India harbours the preferred A2 allele of beta casein; however, genetic improvement of this cattle population by crossbreeding with exotic breeds is spoiling the gene pool as most of the exotic breeds contain A1 allele of the gene.
Original Source [3]
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/milk-proteins-health-issues-and-its-implications-national-livestock-breeding-policy
[2] http://www.indiaenvironmentportal.org.in/files/file/milk_proteins_livestock_breeding_India.pdf
[3] http://www.currentscience.ac.in/Volumes/115/07/1393.pdf
[4] http://admin.indiaenvironmentportal.org.in/category/author/ashish-kumar
[5] http://admin.indiaenvironmentportal.org.in/category/author/bakul-rao
[6] http://admin.indiaenvironmentportal.org.in/category/author/arun-kumar-de
[7] http://admin.indiaenvironmentportal.org.in/category/journal/current-science
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/livestock
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/animal-breeding
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nutrition
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/milk