Calf Colostrum Calculator — How Much Colostrum to Feed a Newborn Calf
Calculate how much colostrum a newborn calf needs at the first and second feeding from its birth weight, and check colostrum quality from a Brix refractometer reading.
How it works
First feeding = birth weight × 8–12% (1 kg of colostrum ≈ 1 L) · Second feeding ≈ 5% of birth weight by 12 hours · Good colostrum: Brix ≥ 22% (≈ 50 g IgG/L)
A calf is born with no antibodies and depends on absorbing immunoglobulin G (IgG) from colostrum in the first hours of life, while its gut can still take up large proteins. Extension guidelines call for 8–12% of body weight — about 4 L for a Holstein — within 2 hours of birth and another feeding by 12 hours, aiming for at least 200 g of IgG in the first meal. A Brix refractometer is the quick on-farm quality test: 22% Brix or more indicates roughly 50 g/L of IgG or better.
Worked example
A 40 kg Holstein calf fed 10% of its body weight needs 4.0 L of colostrum within 2 hours of birth, then about 2.0 L by 12 hours — 6.0 L in total. Colostrum reading 24% Brix is good quality, so 4 L delivers well over the 200 g IgG target.
Sources: University of Wisconsin–Madison Extension — Feeding the newborn calf · Merck Veterinary Manual — Feeding young dairy calves
Frequently asked questions
How much colostrum does a calf need?
About 10% of its birth weight at the first feeding — 3–4 L (3–4 qt) for a Holstein — within 2 hours, plus around 2 L by 12 hours. Small breeds such as Jerseys need proportionally less.
What Brix reading means good colostrum?
A reading of 22% Brix or more indicates about 50 g/L of IgG or higher, which is good quality. Readings of 18–21% are fair, and colostrum below 18% should be replaced or supplemented with a colostrum replacer.
Why must colostrum be fed in the first 2 hours?
The calf’s gut absorbs antibodies best right after birth; absorption falls steadily and is nearly gone by 24 hours. Late or small feedings are the main cause of failed passive transfer and later disease.
What if the calf will not drink enough?
Use an oesophageal tube feeder to give the full first feeding — it is quick and safe when done correctly, and ensures the calf gets its antibodies.
Related calculators
General guidance only — ask your veterinarian about colostrum management for your herd.