VERY rarely. Cows will only calve once a year.
The "life stages" are heifer calf, then heifer, then cow. Cows become cows when they give birth to a calf at around two years of age, however most producers simply like to call those females first-calf heifers or first-calvers rather than cows. Some won't call cows cows until they've had their second calf.
No. Dairy cows have much larger udders than beef cows do. A dairy cow has been selected to produce more milk than what she can feed her calf to meet the farmers' demands for more milk to be produced per cow per day.
Yes. Quite often cows that already had experience calving will have a much easier time popping out a calf than ones (like heifers) that haven't.
Yes. Interestingly, this is a good example of how dairy cows come back into heat sooner than beef cows. Dairy cows that do not have a calf suckling on them (even though they are producing more than twice the amount of milk), actually come back into heat sooner than beef cows. Research has shown that this is because the calf actually inhibits ovulation. If calves are taken off their dams early, (like, 30 to 60 days after birth), the cows will almost always resume cycling much more quickly than if they were raising a calf. All in all, the simple explanation to the question above is this: A cow that gives birth to a stillborn calf (or has aborted early, or has been weaned early) comes back into heat quicker because partly she's not being suckled, and partly because she will dry up (if she isn't made into a surrogate mother for an orphaned calf), resulting in the decreased drain of energy reserves on her body. Hence, she can put those reserves into returning to her normal estrous cycle instead of growing a calf.
Yes, cows can have twins, it is a rare occurrence but does happen. Offspring is known as calves.
Not necessarily. It really depends on the price (in $ per lb) that is currently going for culls and what class they go into. Bred cows and cows with calf at side will go for more than open cows, and fat or well-conditioned cows often will go for a higher price than thin, rangy looking cows. Most often the most money you'll get out of any cattle is the weaned calves that you sell, not the culls.
No, only the "female cows" do. Male "cows" are not cows. They are bulls or steers, which do not produce milk. Female bovines that have had a calf (or at least two) are called cows and those cows produce milk. Young female bovines that have not had a calf are called heifers, and they are not able to produce milk because they have not had a calf yet.
Yes. A bull will mate with a cow more than once during her heat cycle if he is so inclined and if he has few other cows to mate with.
Technically cows are mature female bovines, so the question doesn't apply. However, as far as calves are concerned, yes, but it takes them from 10 to 60 minutes or more for them to get their feet under them, or at least begin to get their feet under them. A calf must be up and suckling no more than 2 hours after birth. The sooner the calf stands up after birth, the better.
A cow is a much larger animal than a calf. A calf is almost a miniature version of his mother (a cow), only he's more leggy, not as blocky, and way more cuter. Cows produce milk, so they would have an udder between their legs that the calf nurses from, whereas the calf only has tiny nipples (if it's a heifer) or a little nut sac (if it's a bull) hanging from between the legs that cannot be viewed until you have the calf on its back and spread its legs apart to determine it's sex. Calves are more bouncy and playful, were as cows are more lazy and mellower and would rather graze or sit and chew their cud than kick up their heels and chase each other around, inviting another to butt heads. Basically, in a nut shell, a calf is the "baby", offspring, or young of a cow that can be either male (a bull calf) or female (a heifer calf), and a cow is a mature female bovine that has had a calf.
At birth clean colostrum is given to a calf ASAP. This prevents calfhood diseases, improves growth rates, and improves the calf's output when at a mature age. Other measures for cows include. A vet recommended vaccination schedule, clean environment, a nutritionally balanced diet (more balanced than a humans!) and proper human handling.
A great percentage would be 100% calf crop! But, as a benchmark, a producer should aim for a 92 to 98% calf-crop from his cowherd, regardless of size. Anything less than that should be of concern to any cow-calf producer.