Dairy farming

Dairy farming is a class of agriculture for the long-term production of milk, which is processed (either on the farm or at a dairy plant, either of which may be called a dairy) for the eventual sale of a dairy product. Dairy farming has a history that goes back to the early Neolithic era, around the seventh millennium BC, in many regions of Europe and Africa. Before the 20th century, milking was done by hand on small farms. Beginning in the early 20th century, milking was done in large scale dairy farms with innovations including rotary parlors, the milking pipeline, and automatic milking systems that were commercially developed in the early 1990s.

Milk preservation methods have improved starting with the arrival of refrigeration technology in the late 19th century, which included direct expansion refrigeration and the plate heat exchanger. These cooling methods allowed dairy farms to preserve milk by reducing spoiling due to bacterial growth and humidity.

Worldwide, leading dairy industries in many countries including India, the United States, China, and New Zealand serve as important producers, exporters, and importers of milk. Since the late 20th century, there has generally been an increase in total milk production worldwide, with around 827,884,000 tonnes of milk being produced in 2017 according to the FAO.

There has been substantial concern over the amount of waste output created by dairy industries, seen through manure disposal and air pollution caused by methane gas. The industry's role in agricultural greenhouse gas emissions has also been noted to implicate environmental consequences. Various measures have been put in place in order to control the amount of phosphorus excreted by dairy livestock. The usage of rBST has also been controversial. Dairy farming in general has been criticized by animal welfare activists due to the health issues imposed upon dairy cows through intensive animal farming.