Kieran Keane, Moorepark Feed Nutrition Lab, explains how analysing amino acids and net energy reveals that even small drops in protein and lysine can impact pig growth and efficiency.
At Moorepark, we have recently begun analysing amino acid levels and calculating net energy values from our feed nutrition lab work. This provides a clearer picture of how different ingredients contribute to pig diets and, ultimately, animal performance.
The encouraging news from our lab data so far is that amino acid levels remain highly consistent with crude protein (CP) content. In fact, for all ingredients tested to date, amino acid concentrations have shown greater than 95% correlation with crude protein content. This means CP values can still serve as a strong predictor of amino acid supply.
However, as highlighted in earlier articles, relying on lower protein ingredients can significantly affect overall dietary protein supply. Below, we examine what happens not only to dietary protein but also to lysine and net energy when ingredient values differ from standard reference tables.
Standard Finisher Diet (Based on Feed Table Values)
A typical finisher ration was formulated to:
- 16% CP
- 9.76 MJ/kg net energy
- 10 g/kg total lysine
| Ingredient (CP @ Feed Table values) | Inclusion in diet (%) | CP contribution (%) | LYS contribution (g/kg) |
|---|---|---|---|
| Barley (10% CP) | 50.0 | 5.0 | 1.9 |
| Wheat (10.5% CP) | 20.0 | 2.1 | 0.6 |
| Soya Hi-Pro (47.2% CP) | 16.0 | 7.6 | 4.6 |
| Maize (8.15% CP) | 10.8 | 0.9 | 0.3 |
| Soya Oil | 1.0 | 0.0 | – |
| Premix | 2.2 | 0.4 | 2.6 |
| Total | 100.0 | 16.0 | 10.0 |
Table 1: Diet Based on Standard Feed Table Values
Diet Using Analysed Ingredient Values
When the same ingredients were analysed in the lab, protein values were lower than the book figures. Using identical inclusions, the diet changes:
| Ingredient (CP @ analysed values) | Inclusion in diet (%) | CP contribution (%) | LYS contribution (g/kg) |
|---|---|---|---|
| Barley (8.3% CP) | 50.0 | 4.2 | 1.6 |
| Wheat (8.8% CP) | 20.0 | 1.8 | 0.5 |
| Soya Hi-Pro (45.7% CP) | 16.0 | 7.3 | 4.4 |
| Maize (6.7% CP) | 10.8 | 0.7 | 0.2 |
| Soya Oil | 1.0 | 0.0 | – |
| Premix | 2.2 | 0.4 | 2.6 |
| Total | 100.0 | 14.4 | 9.3 |
Table 2: Diet Using Analysed Values
Practical Implications
- Crude protein decline: 16.0% → 14.4%
- Lysine decline: 10.0 g/kg → 9.3 g/kg
Since lysine is the first limiting amino acid in pig diets, even a small reduction can impact performance. Other amino acids also decline proportionally, compounding the issue.
Likely outcomes include:
- Reduced average daily gain (ADG) due to insufficient amino acid supply.
- Poorer feed conversion efficiency (FCE), as pigs struggle to utilise energy effectively without adequate protein.
While the examples shown are on the lower end of protein values, they are not unusual. Even if the price is the same as in Table 1, the real cost is higher due to performance losses.
Because energy density remains stable, pigs are unlikely to increase feed intake to compensate for lower protein and lysine. Modern finisher pigs, with high genetic potential for rapid lean growth, require higher amino acid levels. Failure to meet these demands reduces growth and can even lower feed intake, making performance loss more pronounced.
Key Messages
- Lab analysis matters – relying solely on feed table values may mask deficiencies in protein and amino acids.
- Lysine drives performance – small drops in dietary lysine can significantly reduce growth and efficiency.
- Energy isn’t the issue – if net energy remains stable but amino acids fall, pigs cannot “eat their way out of the problem.”
- High-genetic pigs need precision – today’s pigs have exceptional growth potential, but only if diets meet amino acid requirements.
As feed ingredients continue to vary in protein quality, accurate laboratory analyses are increasingly important. Even modest differences in protein and lysine levels can translate into meaningful differences in growth performance and profitability.
Don’t just count crude protein – count lysine too!