breeding white peking ducks on natural pond

american animal aviculture barndoor bionomics bird breed breeding brown cholera cleaning cleans contamination crassipes domestic duck ducks eichhornia eutrophication farm farming feed feet fertilizer fowl gallinarium grows husbandry hyacinth industry invasive keeping macrophyte macrophytes meat mountains organic peking phosphates picturesque plant pollution pond poultry reservoir species thailand utrophication vegetation water white