Did you know that Jersey pregnancies are five days shorter than the average cow? That's right! The average cow is pregnant for 283 days, but the average Jersey cow is pregnant for 278 days.
"The normal gestation period of the dairy cow is 283 days. Based on studies made by the Ohio Experiment Station, however, it is evident that there is variation among breeds. The following figures show the gestation period by breed, as found in this experiment: Ayshire, 278 days; Brown Swiss, 288 days; Guernsey, 283 days; Holstein, 279 days; and Jersey, 278 days. The Ohio station also reported (1) that the gestation period of first-calf heifers is about 2 days less than that of older cows of the respective breeds, and (2) that the gestation period where bull calves are born is about 1 day longer than where females are born." ~M.E. Ensminger, Dairy Cattle Science