Feed efficiency in broilers: why immune function matters

By Mickie Metz, Ph.D.
Technical Innovation Research Scientist
Fortiva

Feed efficiency is one of the most important factors influencing profitability in broiler production. Production managers and nutritionists balance nutrition, genetics and housing conditions to help birds convert feed into growth as efficiently as possible. There’s one other variable often overlooked: the bird’s immune system.

Although it may not always be visible during day-to-day broiler management, immune function can impact how efficiently broilers utilize feed. Birds are protected from disease and can focus energy on efficient growth when immune function is properly balanced.

Understanding immune function in broilers

The immune system comprises signaling molecules called cytokines that help coordinate responses to pathogens. These molecules are essential for protecting birds from disease, but they can also trigger inflammation. Birds may experience unnecessary inflammation that requires more energy if too many pro-inflammatory cytokines are produced.

Instead of trying to suppress immune responses entirely, the goal is to help the immune system respond when needed without becoming overactive. Birds require ample immune activity to protect against pathogens, but not so much that valuable energy is wasted.

How immune function affects performance

When birds face immune challenges, their bodies must divert nutrients and energy toward fighting disease. This shift can affect growth, feed conversion and overall flock performance.

Energy that could be used to support muscle development is instead used to activate immune responses, such as producing immune cells, creating disease-fighting agents and managing inflammation. Birds experiencing immune stress may grow more slowly and require more feed to reach market weight and condition as a result.

Conversely, a strong immune response can affect mortality and carcass quality during periods of high disease pressure. A functional immune system helps birds survive disease challenges, potentially leading to fewer deaths. In addition to reduced mortality, an active immune system can help birds clear infections quickly, reducing morbidity and medication costs.

Hidden cost of immune challenges

Immune-related performance losses are often overlooked. When walking through a broiler house, it can be easy to identify a bird that appears sick. However, many immune challenges occur at the subclinical level.

Even mild immune responses can increase the bird’s energy needs. When the immune system is activated, the bird must use more dietary energy just to maintain basic functions rather than using that energy for growth in systems where every day counts.

Because these changes are subtle, flocks may appear healthy while still experiencing reduced feed efficiency – a response often described as a “silent killer” of feed conversion. Supporting the immune system in a way that minimizes unnecessary inflammation can help birds remain productive, even amid environmental challenges.

Environmental pathogens and disease pressure remain constant challenges in poultry production. Although management and biosecurity practices play a key role in protecting flocks, nutritional tools that support immune balance can provide additional value.

Supporting immune balance

Fortiva has developed a phytogenic feed additive, Remify that supports immune balance and improves feed efficiency in broilers. The product uses whole plant parts instead of isolated extracts or essential oils to provide a broad range of naturally occurring bioactive compounds.

These compounds incorporate polyphenols and other plant metabolites that help regulate inflammation and support gut health. By helping to reduce the impact of pro-inflammatory cytokines, this phytogenic solution can help manage excessive inflammation that would divert energy away from growth.

This product also helps support the integrity of tight junctions in the gut. Strong, tight junctions help maintain the gut barrier, preventing leakage and allowing birds to absorb nutrients more efficiently, thereby supporting better feed utilization and growth.

Research trials show these benefits can translate into measurable performance improvements. In 3 controlled broiler cage trials, feed conversion improved by 4 points at day 28 (p<0.01)¹ and 3 points at day 42 (p=0.026)² with birds fed Remify.^1,2,3 By day 42, birds fed this product experienced a 5.9% greater gain when challenged with coccidiosis.³

Production managers can reduce the hidden energy costs of broiler inflammation and immune stress by helping birds maintain an efficient immune response. This allows birds to focus more energy on growth, which can improve feed efficiency and support more consistent broiler performance.

For more information on how Fortiva can support your nutrition program, click here.

References

1 Broiler Feed Pen Trial 22-F1
2 Schwartz, M., P. Mishra, and S. Crowder. 2024. Effect of a next generation phytogenic blend on broiler growth performance under challenged conditions. Proc. Int. Poult. Sci. For. (Abstr. T174)
3 Metz, M., Davis, E., Mishra, P., & Crowder, S. 2025. Effect of feeding a novel phytogenic feed additive on growth performance and clinical outcomes of broilers administered a mixed Eimeria spp. challenge [Poster presentation]. Poultry Science Association Annual Meeting. (abstr. 504P)

Editor’s note: Fortiva assumes full responsibility for this article’s accuracy and compliance.

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