ABSTRACT
With industrialization and rationalization efforts during the last century, including changes in infrastructure, feed imports, innovations in animal genetics, breeding and mechanization of work, production systems have become more confined, and dairy farms more sparsely scattered and larger. Relating the number of dairy holdings in a country to the number of inhabitants may highlight this trend (Fig. 1). The average herd size is today well above a hundred cows in a number of countries (Anon., 2013c; Fig. 2). Farms with several tens of thousands of cows are seen in the United States, Saudi Arabia and China, and mega dairies of 100 000 cows will soon become a reality.
