The first question has already been answered in a separate question. As for the second, that is all up to the hormones surging through her body that keep her in heat.
Please see the related questions below.
If she's in heat, most definitely. Often a bull will go look for the cow that is in heat, no matter if he's the neighbor's bull or not.
A Jersey cow should be cycling, on average, once every 21 days.
No, the cow will not go into estrus after she becomes pregnant.
Since ovulation occurs a couple days after a cow or heifer has gone into heat or estrus, it occurs once every 17 to 24 days, which is the same time span a female would go into heat.
Normal female hamsters go into heat every 4 days. they stay in heat for 1 day only.
A barren cow is another name for an open cow or heifer. Barren cows are cows that are not pregnant.
First of all, let's do the math here. One year has 365 days, and the average estrous period of a cow is 21 days. So to find how many times a cow will go into heat in one year is 365/21 = 17 days. Thus, a cow (if not bred during that year) will go into heat 17 times in one year.
You stay still when you rope him then when he stays till you go
Every 6 months.
Calves don't grow into cows. They stay small and you brush them as opposed to milking them.
For female animals, they go in heat about every 6 months.
When the boxers are on heat, they usually mate just like the cats.