Figure 2-1 4. Geographic changes in hog and pig production in the U.S. Source: McBride, 1997 (arrows added)

facilities by US based firms, Cargill and Tyson. Sheep and lamb slaughter, while still very small has managed to almost double since 1976—a very different trend than the US.
     Overall, livestock productivity and output in NAE has increased enormously since 1945 with beef, pig meat and milk production almost doubling and a four-fold increase in numbers of poultry. Sheep and goat numbers and produc­tion of meats and other products from this animal stock have remained comparatively stable (data compiled from FAO, Eurostat and USD A).

2.5.2 Drivers of increased livestock output and productivity
The spectacular rises in livestock numbers and productivity seen in NAE over the past 50 years result from six major drivers:
•     Growth in population numbers and wealth, creating strong market demand for meat and dairy products (for example in dairy products a 1 % growth in income gives almost the same increase in consumption in low income countries and about 0.35% increase in wealthy coun­tries (Agra/CEAS, 2004);
•     Strong policies and strategic frameworks within NAE aimed at increasing livestock production;
•     Rules and regulations determining husbandry methods and processing of livestock products;

•     Production-led subsidies that funded output and pro­ductivity increases (Starmer and Wise, 2007);
•     The application of knowledge, science and technology to animal genetics and nutrition, including grassland management and feed formulation; and
•     Improvements in animal and livestock product trans­port systems allowing animal production and slaughter to be situated more closely to major supplies of feed.

The most important contributors of AKST to increased pro­ductivity have been changes in livestock genetics, livestock feeding and stock management systems. For example, selec­tion involved in animal breeding took place at the farm level until the end of the 19th Century resulting in the adaptation of cattle, pigs, sheep, goats and poultry to specific (usually regional) farming and market situations (Hodges, 1999). Yield goals were blended with emphasis on selecting live­stock that would thrive on particular types of land, climate and feed (CIV website).
     By contrast, in the 20th Century livestock breeding was increasingly done in either state-owned or private institu­tions using genetic science. Coupled with advances in land and management practices such as drainage, fertilizer use and better harvest and storage techniques, these breeding programs began to be more yield-oriented to cope with in­creased demands for food from a rapidly expanding urban