The cow is responsible for protecting the calf, not the bull. This is true for not just bovines and moose, but for all ruminants, wild and domesticated.
When he's old enough to be weaned, which would be around six to eight months of age.
Both. A calf is a general term for a young bovine, regardless of sex. A calf, thus, can be either male or female. A male calf is called a bull calf, and a female calf a heifer calf. If the bull calf has been castrated, he is then called a steer calf.
The offspring of a cow is referred to as a calf. A heifer calf is a female calf, a bull calf is an intact male calf, and a steer calf is a castrated male calf (castrated after birth).
calf-bull
Bull calf.
Baby cow, baby calf, bull calf (if male), steer calf (if male and has been castrated), heifer calf (if female), dogie, offspring, progeny, etc.
What calf? Is this calf this bull calf you are concerned about in other different questions, or another calf altogether? Most cases a bull won't hurt nor kill a calf that is even male or around 4 months of age.
A young "male cow" (which is non-existent, by the way) is called a bullock or a young bull or, if not of weaning age, a bull calf. That is, if the so-called "male cow" is intact. If not, it is called a steer calf if castrated and is still relying on its mother's milk, or simply a steer after weaning or after it reaches around a year of age.
Bull calf if intact; steer calf if castrated.
The opposite gender of a bull is a cow. In the context of "bull-calf," which refers to a young male bovine, the opposite would be a heifer, which is a young female bovine that has not yet had a calf. Thus, the opposite gender of a bull-calf would be a heifer-calf.
A young male bovine is commonly referred to as a bull calf.
The cow gave birth to a small male calf. We called the calf Sunday.