When cattle are stressed out, they often eat less. The quicker you can get your herd to eat, the less likely they will get sick
For the first 7 days, it is encouraged to feed the calves at least 2.5 - 3% of their body weight. This can be achieved using available forages with highly palatable supplemental feed or complete feed. Allow the calves to continue build intake through 21 - 28 day starting/weaning program.
It is also very important to have ample bunk space for the calves. Each calf would need about a foot of bunk space so that all calves can be at the feed bunk simultaneously. If you are using starter with intake control properties, it is important to ensure each calf have about 6 - 8 inches of bunk space as not all of them will eat at the same time. As for fenceline-weaned cattle, bunks should be placed perpendicular to the fenceline. This will allow the calves to bump into feed as they are trying to figure out how to get out.
It is also highly encouraged to place mineral tubs along the pen perimeter so that calves encounter them as they are circulating and begin licking the tub. This will cause salivation which will encourage further consumption of feed.
Regardless of any weaning program, it is essential that there is ample of clean and fresh water readily available to the calves. It is also very important to work with your veterinarian on a herd health program to ensure that if any calf ever gets sick, there is a proper plan to get it back on track.