Everyone knows the most critical time for raising healthy calves are the first 21-28 days. That’s because when a calf is born, it has very little fat and can quickly burn what little reserves it has through shivering in temperatures less than 50°. The Fly Away™ Calf Jacket is the only jacket proven to keep calves dry and help them retain more body heat, which causes them to grow faster, retain weight and become healthier.