SELECTIVE BREEDING - COWS

=Selective Breeding - Cow= Cows have been domesticated as early as 9000BC. Selective breeding has produced breeds that are more tolerant to different climates and conditions. Some animals selectively bred for the meat (beef cattle) while others were bred for the milk (dairy cattle). Some of the traits traits have developed over the centuries include: *Increased size and muscle mass (beef) *Increased milk production and udder size (dairy) *Increased fat and protein content ==Examples of Selective Breeding== ===A2 Milk=== There are two forms of the beta-casein protein (A1 and A2) there is some evidence that consumption of the A1 form is associated with slightly higher rates of diseases such as diabetes. This has generated demand for milk that contain only the A2 form of the protein and farmer have used selective breeding to produce milk without the A1 form of the protein. [http://biotechlearn.org.nz/themes/marvellous_milk/a1_or_a2 Biotech Learning Hub A2 milk] ===Belgian Blue=== Belgian Blue is a breed of beef cattle in Belian. The Belgian Blue's extremely lean, hyper-sculpted, ultra-muscular physique is termed, "double-muscling". The double-muscling phenotype is a heritable condition resulting in an increased number of muscle fibers (hyperplasia). The Belgian Blue has a natural mutation in the myostatin gene which codes for the protein, myostatin ("myo" meaning muscle and "statin" meaning stop). Myostatin is a protein that acts to inhibit muscle development. This mutation also interferes with fat deposition, resulting in very lean meat. Cows with the mutation have been selectivity bred Some Useful Links: [http://biotechlearn.org.nz/news_and_events/news/2005_archive/genetic_test_breeds_once_a_day_cows once a day cows] [http://www.fao.org/fileadmin/user_upload/animalwelfare/dairy.pdf natural selection and its impact on the well-being of dairy cows] [https://www.ciwf.org.uk/media/3818641/impact-of-selection-on-health-and-welfare-of-dairy-cattle.pdf implication for welfare of dairy cattle] [http://occupytheory.org/advantages-and-disadvantages-of-selective-breeding/ advantages and disadvantages of selective breeding] [http://letstalkaboutselectivebreeding.weebly.com/impact-on-evolution.html Implications] [http://phys.org/news/2013-05-diet-methane-cows.html ecological implication - methane] [http://cdn.intechopen.com/pdfs-wm/40414.pdf reducing methane emission]