Three main agricultural sub-sectors are active in Sudan: pastoral livestock, cropping and fish production. Livestock production has vast potential, and many animals, particularly cows, sheep, and camels, are exported to Saudi Arabia and other Arab countries. However, Sudan remains a net importer of food. Problems of investment finance, production and transportation remain the greatest constraints to a more dynamic agricultural economy. A major problem which has been growing for decades is the continual loss of open lands previously used for animal grazing to mechanized drylands and irrigated farming.