CP (Crude Protein)
CP — Crude Protein — is the standard measure of total protein content in cattle feed ingredients and complete rations. It is calculated by measuring the nitrogen content of a feed and multiplying by 6.25, based on the assumption that protein averages 16% nitrogen.
The CP formula
CP % = Nitrogen content (%) × 6.25
The 6.25 factor comes from 100 ÷ 16, since dietary protein contains approximately 16% nitrogen by weight.
What CP includes (and doesn't)
CP is a chemical measure of total nitrogen, expressed as protein-equivalent. It includes:
- True protein — actual amino acid chains
- Non-protein nitrogen (NPN) — urea, free amino acids, ammonia, nucleic acids
This is important: a feed labelled "22% CP" may have its nitrogen coming from either true protein or NPN, and the two are not nutritionally identical. For young calves, NPN (like urea) is dangerous because their undeveloped rumen cannot convert it safely. This is why calf starter feed must contain no urea, despite the 22% CP minimum.
BIS minimum CP for compound cattle feed
BIS IS:2052 specifies two CP minimums for compound cattle feed:
| Grade | CP minimum |
|---|---|
| Type-1 (premium) | 22% |
| Type-2 (standard) | 20% |
A product below 20% CP cannot legally be labelled "cattle feed" in India.
CP in common Indian feed ingredients
| Ingredient | Crude protein |
|---|---|
| Soybean meal (Normal grade) | 45–46% |
| Soybean meal (Hipro) | 50% |
| Groundnut cake (decorticated) | 38–45% |
| Mustard cake (DOMC) | 37% min |
| Cotton seed cake (premium) | 22% |
| Wheat bran | 14–17% |
| DORB | 16–17% |
| Maize | 9–10% |
| Maize silage | 7–9% |
| Green fodder (legume) | 14–18% |
| Green fodder (grass) | 8–12% |
| Dry straw | 3–4% |
CP vs Digestible Protein vs Bypass Protein
CP is the gross measure. Two more refined measures matter for ration formulation:
- DCP (Digestible Crude Protein) — the fraction of CP that is actually digested by the animal
- RUP (Rumen Undegradable / Bypass Protein) — the fraction of CP that bypasses rumen degradation and reaches the small intestine intact
A high CP feed is not automatically a great feed — the digestibility and rumen behaviour matter just as much.
Practical use
A lactating cow ration on a dry matter basis should provide 16–18% CP for moderate yielders, 18–20% CP for high yielders. The DCP and TDN calculator computes the total CP of any ration.