DuMOR 16% Layer Poultry Feed Pellets, Calcium Fortified, 50 lb.

Sixteen or 16 may refer to:

• 16 (number), the natural number following 15 and preceding 17
• one of the years 16 BC, AD 16, 1916, 2016

50 may refer to:

• 50 (number)
• one of the following years 50 BC, AD 50, 1950, 2050
• .50 BMG, a heavy machine gun cartridge also used in sniper rifles
• .50 Action Express, a large pistol cartridge commonly used in the Desert Eagle
• .50 GI, a wildcat pistol cartridge
• .50 Beowulf, a powerful rifle cartridge used in the AR-15 platform
• .50 Alaskan, a wildcat rifle cartridge
• 50 Cent, an American rapper
• Labatt 50, a Canadian beer
• Fifty (film), a 2015 film
• "The Fifty", a group of fifty airmen murdered by the Gestapo after The Great Escape in World War II
• 50 (Rick Astley album), 2016
• 50 (Chris de Burgh album), 2024
• Benjamin Yeaten, widely known by his radio call sign "50", a Liberian military and mercenary leader
• "Fifty", a song by Karma to Burn from the album V, 2011
• 50 Virginia, a main-belt asteroid
• Audi 50, a supermini hatchback
• Dodge Ram 50, a compact pickup truck sold in the United States as a rebadged Mitsubishi Triton

Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossilised remnants of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name derives from Latin calx "lime", which was obtained from heating limestone.

Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for calcium supplementation, in the paper industry as bleaches, as components in cement and electrical insulators, and in the manufacture of soaps. On the other hand, the metal in pure form has few applications due to its high reactivity; still, in small quantities it is often used as an alloying component in steelmaking, and sometimes, as a calcium–lead alloy, in making automotive batteries.

Calcium is the most abundant metal and the fifth-most abundant element in the human body. As electrolytes, calcium ions (Ca²⁺) play a vital role in the physiological and biochemical processes of organisms and cells: in signal transduction pathways where they act as a second messenger; in neurotransmitter release from neurons; in contraction of all muscle cell types; as cofactors in many enzymes; and in fertilization. Calcium ions outside cells are important for maintaining the potential difference across excitable cell membranes, protein synthesis, and bone formation.

Poultry () are domesticated birds kept by humans for the purpose of harvesting animal products such as meat, eggs or feathers. The practice of raising poultry is known as poultry farming. These birds are most typically members of the superorder Galloanserae (fowl), especially the order Galliformes (which includes chickens, quails, and turkeys). The term also includes waterfowls of the family Anatidae (ducks and geese) but does not include wild birds hunted for food known as game or quarry.

Recent genomic studies involving the four extant junglefowl species reveals that the domestication of chicken, the most populous poultry species, occurred around 8,000 years ago in Southeast Asia. This was previously believed to have occurred around 5,400 years ago, also in Southeast Asia. The process may have originally occurred as a result of people hatching and rearing young birds from eggs collected from the wild, but later involved keeping the birds permanently in captivity. Domesticated chickens may have been used for cockfighting at first and quail kept for their songs, but people soon realised the advantages of having a captive-bred source of food. Selective breeding for fast growth, egg-laying ability, conformation, plumage and docility took place over the centuries, and modern breeds often look very different from their wild ancestors. Although some birds are still kept in small flocks in extensive systems, most birds available in the market today are reared in intensive commercial enterprises.

Together with pork, poultry is one of the two most widely-eaten types of meat globally, with over 70% of the meat supply in 2012 between them; poultry provides nutritionally beneficial food containing high-quality protein accompanied by a low proportion of fat. All poultry meat should be properly handled and sufficiently cooked in order to reduce the risk of food poisoning. Semi-vegetarians who consume poultry as the only source of meat are said to adhere to pollotarianism.