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Older hens gradually produce fewer eggs, and the eggs are usually larger. [1] Since the average lifespan of a pet layer hen is 8–15 years, [2] henopause has received attention as a potential problem for backyard or urban chicken farmers who are eventually faced with the decision to either slaughter older layers or keep them as non-producing pets.
The traditional modes of reproduction include oviparity, taken to be the ancestral condition, traditionally where either unfertilised oocytes or fertilised eggs are spawned, and viviparity traditionally including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body.
The only living mammals that lay eggs are echidnas and platypuses. In the latter, the eggs develop in utero for about 28 days, with only about 10 days of external incubation (in contrast to a chicken egg, which spends about one day in tract and 21 days externally). [11] After laying her eggs, the female curls around them.
Most Store Eggs Are From Chickens That Roam Free Though many egg cartons have labels such as "cage free," "free range," and "pasture raised," a majority of hens are kept in cages. Only around 29% ...
Forced molting typically involves the removal of food and/or water from poultry for an extended period of time to reinvigorate egg-laying. Forced molting, sometimes known as induced molting, is the practice by some poultry industries of artificially provoking a flock to molt simultaneously, typically by withdrawing food for 7–14 days and sometimes also withdrawing water for an extended period.
During co-nesting, before a bird starts laying its own eggs, it will toss out eggs laid previously by other females. [8] As a result, the last egg-layers may contribute more eggs to the common nest, [8] and this will increase the chances that newly laid eggs bearing the genetic material of that female will have a better chance of survival.
Fertile chicken eggs hatch at the end of the incubation period, about 21 days; the chick uses its egg tooth to break out of the shell. [34] Hens remain on the nest for about two days after the first chick hatches; during this time the newly hatched chicks feed by absorbing the internal yolk sac . [ 42 ]
[2] [3] Chickens raised for eggs are known as layers, while chickens raised for meat are called broilers. [4] In the United States, the national organization overseeing poultry production is the Food and Drug Administration (FDA). In the UK, the national organisation is the Department for Environment, Food and Rural Affairs (DEFRA).