The key to profitability in dairy farming correct rationstop While underfeeding reduces milk yield, overfeeding increases costs and causes metabolic diseases.
In this guide, you will learn the basics of calculating dairy cow ration. At the end of the article:
- How to calculate dry matter consumption (DMT)
- How to balance energy and protein
- Adjusting the ration according to the lactation period
- Practical ration formulation tips
You will have learned.
1. Dry Matter Consumption (DMT): The Basis of Everything
1.1 What is SPG?
Dry matter consumption is the portion of the feed consumed daily by the animal, excluding water. All nutrients (energy, protein, minerals) are calculated on dry matter basis.
1.2 Factors Affecting KMT
| factor | Impact |
|---|---|
| Live Weight | Heavier cows consume more |
| Milk Yield | ~0.4 kg KMT increases for every 1 kg of milk |
| Lactation Period | Low in early lactation, increases after peak |
| Feed Quality | Increases consumption of quality roughage |
| Environmental Temperature | Consumption drops by 10-25% in hot weather |
1.3 SPG Calculation Formula (NRC 2001)
For lactating cows:
YDS: Fat Corrected Milk (kg), CA: Live Weight (kg), LH: Lactation Week
1.4 Practical SPG Table
| Live Weight | 20 kg of milk | 30 kg of milk | 40 kg of milk |
|---|---|---|---|
| 550kg | 18-19 kg SPG | 21-22 kg SPG | 24-25 kg SPG |
| 650kg | 19-20 kg SPG | 22-23 kg SPG | 25-27 kg SPG |
| 750kg | 20-21 kg SPG | 23-24 kg SPG | 26-28 kg SPG |
2. Energy Requirements: Fuel of Milk Production
2.1 Energy Units
Energy units commonly used in Türkiye:
- NEL (Net Energy Lactation): in Mcal or MJ
- ME (Metabolizable Energy): Usable portion of digested energy
2.2 Energy Requirement Calculation
The total energy requirement consists of three components:
| component | formula | Description |
|---|---|---|
| Survival Share | 0.08 × CA^0.75 Mcal NEL | For body functions |
| Milk Production | 0.74 × Milk (kg) Mcal NEL | per kg of milk (~4% fat) |
| pregnancy | +2-4 Mcal in the last 2 months NEL | For calf development |
2.3 Sample Calculation
Living Share: 0.08 × 650^0.75 = 0.08 × 128.8 = 10.3 Mcal NEL
Milk Production: 0.74 × 35 = 25.9 Mcal NEL
Total: 10.3 + 25.9 = 36.2 Mcal NEL/day
Ration NEL density: 36.2 ÷ 23 kg SPG = 1.57 Mcal/kg KM
3. Protein Requirement: Protein For Milk Protein
3.1 Protein Concepts
- HP (Crude Protein): Total nitrogen × 6.25
- MP (Metabolizable Protein): Actual protein absorbed in the small intestine
- RDP (Rumen Degraded Protein): For Romanian microbes
- RUP (Protein Not Degraded in the Rumen): bypass protein
3.2 Protein Requirement
| Milk Yield | HP (%KM) | MP (g/day) |
|---|---|---|
| 20-25kg | %14-15 | 1800-2100 |
| 25-35kg | %15-16 | 2100-2600 |
| 35-45kg | %16-17 | 2600-3200 |
| 45+kg | %17-18 | 3200+ |
3.3 Energy-Protein Balance
- More protein, less energy: Urea increases, liver gets tired, fertility decreases
- Less protein, more energy: Milk protein decreases and fat occurs
Ideal ratio: 45-50 g MP per 1 Mcal NEL
4. Ration According to Lactation Period
4.1 Lactation Periods
| Period | Duration | feature |
|---|---|---|
| Dry Period (Early) | Going dry - 3 weeks before birth | Low energy, breast rest |
| Dry Period (Late) / Transition | 3 weeks before birth - birth | Energy increase, rumen adaptation |
| Early Lactation | 0-70 days | Negative energy balance, peak efficiency |
| Mid Lactation | 70-200 days | Positive energy balance, fitness recovery |
| Late Lactation | 200-305 days | Productivity decreases, pregnancy progresses |
4.2 Ration Characteristics by Periods
| Parameter | Dry (Early) | Transition | Early Lact. | Medium Lact. |
|---|---|---|---|---|
| NEL (Mcal/kg) | 1.25-1.35 | 1.50-1.60 | 1.65-1.75 | 1.55-1.65 |
| HP (%) | 12-13 | 14-15 | 16-18 | 15-16 |
| NDF (%) | 40-45 | 33-38 | 28-32 | 30-35 |
| Concentrate (%) | 20-30 | 35-45 | 55-65 | 50-55 |
5. Practical Ration Formulation
5.1 Basic Principles
- Roughage basis: Min. 40% roughage (based on DM)
- NDF control: Min. 28%, max. 40% (min. 21% from forage)
- Starch control: Max. 25-28% (risk of acidosis)
- Oil limit: Max. 6-7% (for rumen function)
5.2 Sample Ration (35 kg milk/day)
| bait | Quantity (kg KM) | % Ration |
|---|---|---|
| Corn Silage | 8.0 | 35% |
| Clover Dried Grass | 3.5 | 15% |
| Corn (cracked) | 4.5 | 20% |
| Barley (crushed) | 2.0 | 9% |
| Soybean Meal | 2.5 | 11% |
| Cotton Seed Meal | 1.5 | 7% |
| Mineral-Vitamin Premix | 0.5 | 2% |
| TOTAL | 22.5 | 100% |
Nutritional values of this ration:
- NEL: ~1.65 Mcal/kg KM
- HP: ~16.5%
- NDF: ~32%
- Roughage ratio: ~50%
5.3 Ration Checklist
✅ Things to Do:
- Have the roughage quality analyzed
- Use TMR (Total Mixed Ration)
- Feed 2-3 times a day
- Make sure clean water is always available
- Track body condition score
❌ Things to Avoid:
- Sudden ration changes
- Extremely concentrated feed (65+%)
- Moldy or spoiled feed
- Insufficient roughage
- Imbalanced mineral ratios
6. Common Mistakes and Solutions
| Error | Conclusion | Solution |
|---|---|---|
| Low energy during transition period | Ketosis, fatty liver | Increase energy gradually for 3 weeks before birth |
| Overly concentrated in early lactation | Rumen acidosis, lameness | Increase concentrate gradually, maintain NDF |
| Insufficient effective fiber | Milk fat decreases, acidosis | Min. Give 2-3 cm long roughage |
| Unbalanced Ca:P ratio | Milk fever, bone problems | Keep Ca:P ratio 1.5-2:1 |
7. Conclusion
Ration formulation is critical for a successful dairy farming operation:
- Calculate KMT correctly - The basis of everything
- Establish energy-protein balance - For efficiency and health
- Adjust according to lactation period - There is no single ration
- Pay attention to roughage quality - Cheap feed becomes expensive
→ Calculate Dairy Cow Ration (NRC/NASEM)
Bibliography
National Research Council. (2001). Nutrient requirements of dairy cattle (7th rev. ed.). National Academies Press.
NASEM (National Academies of Sciences, Engineering, and Medicine). (2021). Nutrient requirements of dairy cattle (8th rev. ed.). National Academies Press. https://doi.org/10.17226/25806
Allen, M. S. (2000). Effects of diet on short-term regulation of feed intake by lactating dairy cattle. Journal of Dairy Science, 83(7), 1598-1624. https://doi.org/10.3168/jds.S0022-0302(00)75030-2
Drackley, J. K. (1999). Biology of dairy cows during the transition period: The final frontier? Journal of Dairy Science, 82(11), 2259-2273. https://doi.org/10.3168/jds.S0022-0302(99)75474-3
Grummer, R. R. (1995). Impact of changes in organic nutrient metabolism on feeding the transition dairy cow. Journal of Animal Science, 73(9), 2820-2833. https://doi.org/10.2527/1995.7392820x
Mertens, D. R. (1997). Creating a system for meeting the fiber requirements of dairy cows. Journal of Dairy Science, 80(7), 1463-1481. https://doi.org/10.3168/jds.S0022-0302(97)76075-2
Nocek, J. E. (1997). Bovine acidosis: Implications on laminitis. Journal of Dairy Science, 80(5), 1005-1028. https://doi.org/10.3168/jds.S0022-0302(97)76026-0
Van Soest, P. J. (1994). Nutritional ecology of the ruminant (2nd ed.). Cornell University Press.