This is similar to the pregnancy period of a woman, which is closer to around 9 months or ~260 days. However, actual gestation period of a cow can range from 270 days to 295 days, depending primarily on breed[s], age, body condition and nutritional health.Gestation period is also controlled by genetics, but not rate of maturity.his is similar to the pregnancy period of a woman,  which is closer to around 9 months o â¦ r ~260 days.    However, actual gestation period of a cow can range from 270 days  to 295 days, depending primarily on breed[s], age, body condition  and nutritional health.
Whereas fertilized chicken eggs usually take exactly 21 days to hatch, most duck eggs take 28 days, apart from Muscovy ducks. As a general rule of thumb, the eggs of Muscovy ducks take 35 days, but once again, it can vary slightly depending on conditions.
This is called a 'brood patch'. Different birds sit on their eggs for different lengths of time. Bigger birds lay bigger eggs which take longer to hatch. Blue tits incubate their eggs for two weeks but swans sit on theirs for nearly six weeks!Most birds lay one egg a day until the eggs are all laid. Some birds lay up to 15 eggs but others lay only one.But the parent birds do not start to incubate the eggs until they are all laid.lue tits incubate their eggs for two weeks but swans sit on theirs for nearly six weeks! Most birds lay one egg a day until the eggs are all laid. Some birds lay up to 15 eggs but others lay only one.