As the calving season approaches, cows will show typical signs that indicate parturition is imminent. One change that is gradually seen, is udder development, or making a bag. Another is the relaxation and swelling of the vulva, or springing. These indicate the cow is due to calve in the near future.

There are many differences between individual animals in the development of these signs, and certainly age is a factor. The first-calf heifer, particularly in the milking breeds, develops an udder for a very long time, sometimes for two or three months before parturition. The springing can be highly variable too.

The immediate signs that usually occur within 24 hours prior to calving would be relaxation of the pelvic ligaments and strutting of the teats. These can be fairly dependable for the owner that watches his cows several times a day during the calving season.

The relaxation of the pelvic ligaments really can not be observed in fat cows, (body-condition score 7 or greater). However, relaxation of the ligaments can be seen clearly in thin or moderate body condition cows and can be a clue of parturition within the next 12 to 24 hours. Strutting of the teats is not as dependable. Some heavy milking cows will have strutting of the teats as much as two or three days before calving, while a thin, poor milking cow may calve without strutting of the teats.

Another indication seen 12 hours before calving is variable behavior such as a cow that does not come up to eat, or a cow that isolates herself into a particular corner of the pasture. However, most cows have few behavioral changes until the parturition process actually starts.