Stock raising is generally a supplementary activity on small farms. In 2001 there were 1,440,000 head of cattle, 1,000,000 hogs, 1,942,000 goats, 501,000 horses, 152,000 sheep, and 5,500,000 poultry. The hog population was decimated by African swine fever in 1979, and careful efforts at replacement have been unsuccessful. In the mid-1990s, the poultry industry contracted from over 100 commercial producers to less than 10. In addition to the embargo and political uncertainty, the industry is under competitive pressure of low cost poultry imports from the United States. Poultry production has not risen enough to fill the vacuum in the rural diet. Extension work directed by the Department of Agriculture's educational center at Damien has helped to stabilize animal husbandry. Poultry production slowly increased from about 6,000 tons per year in the mid-1990s to 8,700 tons by 2001. Native stock has been upgraded by the introduction of hogs and cattle from abroad, particularly the zebu, which does well in the hot, dry plains. Two major stock-feeding centers operate at Port-au-Prince and Cap-Haïtien. Livestock products in 2001 included 96,000 tons of meat, 24,500 tons of goat's milk, 42,000 tons of cow's milk, and 4,200 tons of eggs.