The gestational period of a horse is 11 months and cow is range from 270 days to 295 days.
The gestation length for all breeds of cattle averaged together is 283 days. The range is 279 for Jersey and up to 292 for Brahman. On the average, the Continental breeds of Charolais, Simmental, and Limousin exhibit gestation lengths of 289 days. English-bred cattle such as Angus, Shorthorn, and Hereford exhibit, on the average, shorter gestation lengths of 281, 282 and 285 respectively. Within those breeds the average gestation length can vary an additional twelve days on either side of the average for the breed. Occaisonally a mare will give birth at a shorter period than 11 months long, which can be at 10.5 months. Anytime before that foals that are born are deemed premature. On average, 340 days but a healthy gestation can be as few as 315 days and as much as 370. The gestational period of a horse is 11 months. 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. Below you will find the gestation chart for your use in determining due dates for beef cattle. Just simply select the date you bred the cow to find the expected calving date. Chart is based on 283 days of pregnancy. This is similar to the pregnancy period of a woman,  which is closer to around 9 months o … 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. Length of gestation is primarily an  inherited trait, but has nothing to do with the rate of maturity of  a certain breed or an individual animal.
http://www.manzanoangus.com/back-to-basicsgestation-length-of-the-beef-cow-versus-dystocia/ http://www.answers.com/Q/How_long_is_the_gestation_period_of_a_horse http://www.answers.com/Q/What_is_the_gestation_period_of_a_cow_or_heifer http://www.hereford.org/seedstock/gestation-chart http://www.answers.com/Q/What_is_the_gestation_period_of_a_cow_or_heifer
gestation period horses and cows