That really depends on the breed of the heifer and her age. At the most she should be around 24 months of age when she calves. Brahman and Brahman-influenced heifers should be a few months older. Weight really isn't a factor in this type of question.
According to the below website, your BMI is at 48.7, which puts you largely above healthy weight. A healthy BMI should be between 18.5 and 24.9. So according to some rouch calculations, at your height a healthier weight would be closer to say, 160 lbs.
There are several different varieties of cantaloupe and other factors that affect their weight. A cantaloupe is between 1.5 and 4kg, or 4 to 9 lbs.
Other things (the volume and shape) being equal, a greater weight would cause a greater terminal velocity.
The weight of a carot is equal to 200 milligrams. Carots are used to measure and weigh diamonds. A diamond's worth is determined by how many carots it has.
290 pounds is 20.71 stones.
Put a calving-ease yearling bull in with her.
The anestrous period for a cow or heifer after calving is 45 to 60 days, but can range between 25 to 80+ days.
This all depends on the individual first-calf heifer. Some may be aggressive after calving, others will be quiet and not cause you any trouble.
That all depends on the age of the heifer. The older the heifer, the heavier she'll be.
A cow that has NEVER had a calf in her lifetime is called a Heifer. A cow that has not had a calf YET is a heavily pregnant or heavy-bred, or a short-bred or long-bred cow. A cow that has not had a calf during a calving season is called a barren cow, an open cow, a cystic cow, a cull cow, a meat/slaughter cow, a poor cow, a free-loader, etc.
A heifer should be getting bred at that age, not calving. But, I digress. Unless the heifer has been knowingly and purposely bred to a low birth-weight bull, I wouldn't count on it. Keep a constant eye on her when she gets to the point where she's about to "pop" any day and keep tabs on her progress. If she's having any difficulty, get the veterinarian out to see if she will have to have a calf pulled of if a Caesarean section (C-section) needs to be done on her.
It depends on you and what your plans are for the female and her calf and your experience with calving females. Often bred heifers are cheaper than bred cows, but they can be a pain in the rear when it comes down to calving, because they're predictably unpredictable. A bred cow will have more experience delivering and mothering up to a calf than a heifer will, and if you intend on keeping the calf for breeding (IF it's a heifer), then more often than not, if the cow's a good dam, the calf will be a good keeper. Not so for heifers: any calf that they birth should be raised for slaughter or sold, as they're not as good quality to keep for breeding purposes as her second, third, fourth, etc. calves will be. So it's all up to you.
Low birth weight is the genetics that a bull passes on to his offspring to be able to be small at birth so that the calf can easily fit through the pelvic opening of his dam. This is important as heifers have small pelvic openings and will have a harder time delivering a calf if the bull they are bred to is not a low birthweight or high calving-ease bull.
Birthing, or calving.
As a general rule, a good fertile cow or first-calf heifer should be able to come back into heat in 45 to 60 days after calving. But if you need your females to meet the same calving date as the previous year, you will have to account for at least 80 to 90 days of rest before you can get her bred again. All cows and heifers should be in their normal estrous cycles by the time the annual breeding season starts again, and not just starting to come into heat. If you're finding that's the case, then you really need to make some culling decisions in your herd.
There really isn't a specific age when a heifer is too old to be bred. However, past five to seven years of age can be considered "too old" to get her bred. And yet, you still can get her bred if you use a really calving-ease (and proven) bull on her, just like you would with 15 month old heifers.
That all depends on the gender of that calf. Bull or heifer or steer?