Modern ration formulation is no longer focused solely on crude protein percentages, but rather on the adequacy and ratio of amino acids.
Amid the challenges faced by the poultry industry—ranging from fluctuating raw material prices and disease risks to increasing demands for efficiency—nutritional innovation has become increasingly crucial. One approach that has begun to gain attention is low-protein feed formulation, aimed at improving efficiency while reducing both costs and environmental impact.
Several studies have found that reducing crude protein (CP) levels from 17% to around 13–15% can maintain production performance and feed efficiency while reducing nitrogen excretion by approximately 10–15%. However, lowering crude protein also has the potential to reduce egg weight and egg quality, making the balance of amino acids (AA) a key factor in maintaining productivity and digestive health in laying hens.
Modern ration formulation is therefore no longer oriented merely toward crude protein percentages, but toward the adequacy and balance of amino acids. The Ideal Protein Concept states that when all essential amino acids are provided in the correct proportions, crude protein levels can be reduced without compromising performance. This strategy also contributes to lower nitrogen excretion, making poultry production more environmentally friendly.
According to Bregendahl et al. (2008), the ideal amino acid requirement pattern for laying hens (SIDAA) is:
Lys : Met : Trp : Thr : Met + Cys : Arg : Ile : Val = 100 : 50 : 21 : 70 : 91 : 104 : 80 : 88.
Even so, the optimal threshold for reducing crude protein and the best strategy for balancing amino acids in low-protein diets remain unclear.
Therefore, the authors considered it necessary to evaluate low-protein diets supplemented with several essential amino acids in terms of their effects on production performance, egg quality, and intestinal health, in order to support the more precise application of low-protein nutrition strategies in laying hens.
A total of 384 Hy-Line laying hens aged 33 weeks were divided into four treatment groups with eight replicates. Each replicate consisted of 12 birds and the experiment was conducted for 20 weeks. The treatment groups were as follows:
  • Control: 15.91% protein supplemented with 4 essential amino acids
    (Lys : Met : Thr : Trp = 100 : 45 : 73 : 21 [Lys 0.75%])
  • LPF: 14.53% protein supplemented with 4 essential amino acids
    (Lys : Met : Thr : Trp = 100 : 45 : 73 : 21 [Lys 0.75%])
  • LPS: 14.58% protein supplemented with 8 essential amino acids
    (Lys : Met : Thr : Trp : Arg : Leu : Ile : Val = 100 : 45 : 73 : 21 : 101 : 138 : 96 : 78 [Lys 0.75%])
  • LPH: 13.05% protein supplemented with 8 essential amino acids
    (Lys : Met : Thr : Trp : Arg : Leu : Ile : Val = 100 : 45 : 73 : 21 : 101 : 138 : 96 : 78 [Lys 0.75%])
The hens were housed in a closed house system with a controlled environment. During the study, feed was provided twice daily (09:00 and 15:00), drinking water was supplied ad libitum, and a lighting program of 16 hours light and 8 hours dark was applied using incandescent lamps with an intensity of 15 lux. Disinfection was carried out weekly, the house was cleaned regularly, and room temperature was maintained at 20–22°C with 50–65% humidity.
The parameters observed included production performance, egg quality, plasma hormones, intestinal morphology, protein expression, amino acid digestibility, and gut microbiota. These measurements provided a comprehensive picture of what actually occurs within the hen’s body when protein intake is reduced.
Protein Percentage Threshold and Amino Acid Requirements
The results showed that the limit of crude protein reduction has clear physiological implications. The LPF group (CP 14.53% + 4 AA) experienced an increase in feed conversion ratio (FCR) compared with the control, indicating that reducing protein without expanding the amino acid balance lowers feed efficiency.
In the LPH group (CP 13.05% + 8 AA), FCR also increased and was accompanied by declines in egg production and egg weight. This suggests that excessive protein reduction cannot be fully compensated, even when the amino acid profile is expanded.
This article is an excerpt from the Research section of Poultry Indonesia magazine, March 2026 edition. Read the full article in Poultry Indonesia Magazine – March 2026 Edition. For subscriptions or further information, contact:
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