Published: December 2025
Publisher: Industrial Experts Forums Pakistan
Author: Dr. M. Shoaib
Group Nutritionist, PK Feeds & Hateem Corn Products, Gujranwala – Pakistan
Email: shoaib.imtiaz43@gmail.com
Calcium (Ca) and Phosphorus (P) are two essential elements in poultry nutrition that must be precisely calculated in feed formulations. Different regions or feed formulations may use distinct terms like Digestible, Available, and Retainable to describe how these minerals are utilized by poultry. The distinction between these terminologies is as follows:
1. Digestible Phosphorus (Dig-P or Digestible-P)
Definition:
Digestible phosphorus represents the portion of phosphorus that can be broken down and absorbed through the digestive tract, but it may not necessarily be retained by the body. This is a direct measure of phosphorus that has passed through digestion but doesn’t indicate if it is used or lost through excretion.
Common use:
Digestible phosphorus is commonly used in European feeding systems and focuses on absorption rather than retention.
Example:
A certain percentage of phosphorus in a feed ingredient might be digestible, but not all of that phosphorus will be retained in the body.
2. Available Phosphorus (Avail-P or Av-P)
Definition:
This refers to the portion of phosphorus that can be absorbed by the bird and is physiologically usable for metabolism. It is a measure of how much phosphorus can be utilized by the bird after it passes through the digestive system.
Common use:
This term is often used in North America and other regions.
Example:
Inorganic phosphorus sources like di-calcium phosphate are mostly available, but plant-based phosphorus (like that from grains) may not be fully available without the use of phytase enzymes.
Table 1: Total P, Phytate P, Non-Phytate P and True Digestible P Content of Common Feed Ingredients (g/kg)
| Ingredient | Total P | Phytate P | Non-Phytate P | Digestible P |
|---|---|---|---|---|
| DCP | 180 | – | 180 | 99 |
| MCP | 220 | – | 220 | 187 |
| Corn | 2.54 | 1.79 | 0.75 | 1.72 |
| Wheat | 3.22 | 2.11 | 1.11 | 1.49 |
| Sorghum | 2.37 | 1.82 | 0.55 | 0.78 |
| Canola Meal | 9.70 | 6.88 | 2.82 | 4.55 |
| Soybean Meal | 6.46 | 4.31 | 2.15 | 5.16 |
| Corn-DDGS | 8.18 | 3.82 | 4.36 | 5.94 |
| MBM-1 | 37.5 | – | 37.5 | 26.0 |
| MBM-2 | 60.2 | – | 60.2 | 36.6 |
| MBM-3 | 59.8 | – | 59.8 | 25.1 |
3. Retainable Phosphorus (Retain-P or Retained-P)
Definition:
Retainable phosphorus is the portion of phosphorus that is not only absorbed but also retained in the bird’s body for various physiological functions, such as bone mineralization or egg production. It excludes the phosphorus that is absorbed but later excreted.
Common use:
This term is sometimes used in more precise or research-driven contexts where phosphorus retention and utilization need to be measured.
Example:
Phosphorus that is retained in bones, eggs, and tissues would count towards retainable phosphorus, while any that is absorbed but excreted in urine or feces would not.
Calcium (Ca)
Similar concepts can apply to calcium in terms of availability and digestibility, but calcium is usually calculated as total calcium in most regions.
1. Digestible Calcium
The amount of calcium that is absorbed from the digestive tract, regardless of how much is retained.
2. Available Calcium
The portion of calcium that can be utilized by the bird after digestion.
3. Retainable Calcium
The calcium that remains in the bird’s body (e.g., bones, eggs).
Table 2: Total and Digestible Calcium Content of Ingredients (%)
| Ingredient | Total Ca | Ca Digestibility | Digestible Ca |
|---|---|---|---|
| Limestone | 38.0 | 0.55 | 21.0 |
| Meat and Bone Meal | 10.0 | 0.50 | 5.0 |
| Oyster Shell | 37.0 | 0.44 | 16.3 |
| DCP | 22.0 | 0.36 | 7.9 |
| MCP | 16.0 | 0.32 | 5.1 |
| Canola Meal | 0.60 | 0.31 | 0.19 |
| Poultry By-Product Meal | 4.0 | 0.29 | 1.15 |
| Fish Meal | 6.7 | 0.24 | 1.61 |
| Soybean Meal | 0.35 | 0.54 | 0.19 |
| Corn | 0.01 | 0.70 | 0.007 |
| Wheat | 0.04 | 0.71 | 0.028 |
Key Differences
- Retainable vs Digestible: Retainable focuses on what remains in the body for long-term use, whereas digestible focuses only on what gets absorbed during digestion.
- Available vs Digestible: Available refers to phosphorus that the bird can actually use physiologically, while digestible refers only to gut absorption.
- Practical Impact: Use of phytase enzyme increases phosphorus availability and digestibility but may not always affect retention equally.
ADDITIONAL TERMS AND CONCEPTS
There are a few additional terms and concepts related to calcium (Ca) and phosphorus (P) in poultry diets, which are important for understanding their bioavailability and utilization. These terms are often used in more advanced nutrition discussions:
1. Phytate Phosphorus (Phytate-P)
Definition: This refers to phosphorus that is bound in the form of phytate (or phytic acid) in plant-based ingredients such as grains and oilseeds. Poultry have limited ability to digest phytate phosphorus without the help of the enzyme phytase, making it largely unavailable unless phytase is added to the feed.
Importance: Many feed formulations now include phytase to increase the availability of phytate-bound phosphorus.
2. Non-Phytate Phosphorus (NPP)
Definition: This is the portion of phosphorus that is not bound to phytate and is naturally available to the bird for absorption and use. Non-phytate phosphorus is usually more bioavailable than phytate-bound phosphorus.
Common use: In feed formulations, non-phytate phosphorus is calculated separately to ensure adequate phosphorus levels are provided after accounting for phytate-bound phosphorus.
3. Total Phosphorus (Total-P)
Definition: This is the total amount of phosphorus present in the feed, including both the phytate-bound phosphorus and the non-phytate phosphorus. It does not account for bioavailability or how much is usable by the bird.
Importance: Total phosphorus gives a broader picture of phosphorus content but doesn’t give insight into how much can actually be utilized by the bird unless further analysis (like available, retainable, or digestible phosphorus) is done.
4. Bioavailable Phosphorus (Bioavailable-P)
Definition: Similar to available phosphorus, but with a focus on how much phosphorus can be absorbed, utilized, and retained by the bird based on its physiological needs. It considers the efficiency of the bird’s body to use the phosphorus for growth, egg production, bone health, etc.
5. Net Phosphorus (Net-P)
Definition: This refers to the amount of phosphorus that is retained in the bird after accounting for what is absorbed and what is lost through excretion. It reflects the true efficiency of phosphorus utilization in the bird.
6. Apparent vs. True Digestibility (Phosphorus or Calcium)
Apparent Digestibility: Measures absorption based on fecal output, without accounting for endogenous losses.
True Digestibility: Accounts for endogenous losses, providing a more accurate estimate.
7. Endogenous Phosphorus Losses
Definition: These are phosphorus losses that occur naturally within the bird’s digestive system, such as phosphorus secreted by the bird’s own tissues during digestion.
8. Phosphorus Retention Efficiency
Definition: This is a ratio or percentage that indicates how efficiently phosphorus is retained in the bird’s body after ingestion and absorption.
9. Soluble Calcium
Definition: Soluble calcium is the portion of calcium in the diet that can dissolve in the gut and be absorbed by the bird. It is influenced by calcium form and gut pH.
Summary of Additional Terms
- Phytate Phosphorus (Phytate-P)
- Non-Phytate Phosphorus (NPP)
- Total Phosphorus (Total-P)
- Bioavailable Phosphorus (Bioavailable-P)
- Net Phosphorus (Net-P)
- Endogenous Phosphorus Losses
- Phosphorus Retention Efficiency
- Apparent vs. True Digestibility
- Soluble Calcium
Each of these terms helps refine the understanding of mineral utilization in poultry diets, ensuring optimal nutrient absorption and efficiency in feed formulations.
List of Several Pakistani Companies dealing in Phytase
| Sr No. | Company Name | Product Name | Product Source / Brand Name | Composition | Recommended Dose (g/ton) |
|---|---|---|---|---|---|
| 1 | Nutrion | Thermostable Phytase, Powder | Beijing Strowin Biotechnology Co. Ltd, China | 10,000 FTU/g | 50–100 |
| 2 | Nutrion | Thermostable Phytase, Granular | Beijing Strowin Biotechnology Co. Ltd, China | 10,000 FTU/g | 50–100 |
| 3 | Vennsol Enterprises | Vennphy Plus | N/A | 10,000 FTU/g | 50–100 |
| 4 | Rayan Biosciences & Gilani Biosciences | Pro Phytase | N/A | 10,000 FTU/g | 50–100 |
| 5 | LCI Pakistan | TN-PHY | Trow Nutrition | 24,000 FTU/g | 25–50 |
| 6 | HMZ Nutrition | Sunzyme | SunHy, China | 20,000 FTU/g | 25–50 |
| 7 | Orient Animal Health | Avemix P | Aveve, Belgium | 10,000 FTU/g | 50–100 |
| 8 | Agriprom, Pakistan | PHYTINgest | CJ Bio | 10,000 FTU/g | 50–100 |
| 9 | Agrovisions | Winzyme HTR | Suntaq, China | — | — |
| 10 | Hivet Animal Health Business | PhyzmProt | Hangzhou East Biochem, China | 5,000–20,000 FTU/g | Variable |
| 11 | Ghazi Brothers | SaturnPHY | — | 10,000 FTU/g | 50–100 |
| 12 | Polaris Life Sciences | Microtech & Microtech Plus | VTR Biotech, China | 10,000–20,000 FTU/g | 25–100 |
| 13 | Agriz Life Sciences | Habio Phytase | Habio bioengineering, China | 10,000 FTU/g | 50–100 |
| 14 | DMG Pharmaceuticals | Nuzyme | Compro, China | 10,000 FTU/g | 50–100 |
| 15 | Nutrix International | Megaphy-G | Peli Biochem Tech., China | 10,000 FTU/g | 50–100 |
| 16 | Nexus Agrinutrition | Bestphase HT | Bestzyme, China | 10,000–25,000 FTU/g | 25–100 |
| 17 | Shivani Traders | Hizyme Phy 10000SCT | Bionutri Pte. Ltd., Singapore | 10,000 FTU/g | 50–100 |
| 18 | Ayar Biosciences | Phytotech | Shandong Lonct Enzyme Co., China | 10,000 FTU/g | 50–150 |
| 19 | Bild Agro Pakistan | Smizyme Vinzyme TS | Beijing Smile Feed Sci. & Tech. Co., Ltd., China | 10,000 FTU/g | 50–100 |
| 20 | UM Enterprises | Axtra® PHY GOLD | Danisco Animal Nutrition (IFF) | 10,000 FTU/g | 50–100 |