Description
The first few weeks of a calf’s life are critical for long-term health and performance. After calves receive antibodies from maternal colostrum or colostrum replacer, they enter a vulnerable transition period before their own immune systems are fully developed.
This stage, often called the “immunity gap,” can increase the risk of digestive challenges, scours, reduced feed intake, and slower growth.
First 21 is specifically designed to help bridge this critical immunity gap during the first three weeks of life. As a nutritional supplement, First 21 provides research-supported ingredients that help support calf immunity, digestive health, and growth performance during this important stage of development.
First 21 Supplement can be added to pasteurized whole milk or calf milk replacer. Ideal for producers who:
- Feed pasteurized whole milk
- Use an existing milk replacer program
- Want additional immune and digestive support during the first weeks of life




