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.
Chicken eggs are incubated at 99 to 99.5 degrees. Chicken eggs incubate for 21 days. Your countdown for days starts when you put your eggs in your incubator. It does not start when the hen lays her eggs.Duck eggs are incubated at 99 to 99.5 degrees.Mallard and domestic duck eggs (including Ancona) incubate for 28 days. Muscovy duck eggs incubate for 35 days. You start counting your days when you put the eggs in your incubator.t does not start when the hen lays her eggs. Duck eggs are incubated at 99 to 99.5 degrees. Mallard and domestic duck eggs (including Ancona) incubate for 28 days. Muscovy duck eggs incubate for 35 days.