Yes, always.
A cow that is very close to calving or which calving is imminent.
Calving.
A cow typically begins to "bag up," or develop udder fullness, about 1 to 2 weeks before calving. This process can vary depending on the individual cow and her specific circumstances, including breed and parity. Signs of bagging up include increased firmness and size of the udder, which indicates that the cow is preparing to produce milk for her calf. Keeping an eye on these changes can help farmers anticipate the calving process.
A breaching cow could mean a cow that is calving out a backwards calf.
The udder will only swell, the cow is dropping her milk into the milk cisterns in the udder for the calf to suckle.
A cow that is close to calving, and is far along in her gestation period.
Parturition or calving, just like with any other cow.
the cow will get restless and will isolate itself from other cows.
A calving pen, or out on the pasture.
For one cow, it's usually 11 to 12 months in between each calving. For a cow-calf operation with defined breeding and calving seasons, it's always 12 months in between the start of one season to the start of the next.
Absolutely nothing. A pig doesn't care nor cannot help a calving cow.
Don't wait. This is a good time to put on the calving chains and start pulling. Make sure the cow is secured in a head gate first, though, before you latch on the calving chains on the calf.