As soon as they are curious enough to start experimenting with what Momma is eating, which would be when they're less than a few days old. But hay and grass isn't their staple diet at that age, because they still depend on their mother's milk until they're between 3 and 6 months of age.
When calves start eating grass they also start ruminating.
When calves that have not started eating solid food (grain, hay, etc.) are slaughtered for meat, the product is called "veal".
Beefalo bulls weigh an average of 2000 lbs. Cows average around 1500 lbs. Beefalo calves are typically born smaller than beef calves but they gain weight quickly and normally catch up in size by the time they start eating grass and hay.
The sheep were eating hay in the field.
It depends on what purpose you have for these calves, and what you wish to feed them. But really, you just start feeding them, start training them to eat whatever you set out for them, and let their curiosity get the best of them and get them interested in eating what you've set out for them to start eating. But, it's best to feed them what you have been feeding them prior to weaning, and continue feeding them this, slowly switching over to what you are intending to feed them in the first place.
If a horse is hungry straw is similar enough to hay that they will eat it.
Calves or cattle, wheat, hay, barley, and dairy products
Kids can start nibbling on hay from a week old - they will copy their mother's behaviour but they can't be weaned until at least 12 to 14 weeks of age as their rumen needs to fully develop.
This could be for a number of reasons: they are eating too much grain before eating hay, they are sick, or the hay could be molding or tasting bad.
Not really, no. Calves should be eating plant-type feed, not insects or insect larvae.
A newborn calf must be up and suckling within an hour after it is born. This is important because it needs colostrum in order to survive and decrease its chances of getting sick should any pathogens happen by, thereby decrease its chance of dying at a young age from illness.
After it calves