Controlling Necrotic Enteritis Without Antibiotic Growth Promoters: What Can Feed-Based Strategies Offer?

When antibiotic growth promoters are no longer the main option for controlling necrotic enteritis (NE), prevention has to begin with the intestinal environment. Feed-based interventions can influence microbial balance, intestinal immunity, barrier function and pathogen load, giving the veterinarian several ways to reduce the conditions that favour Clostridium perfringens. 

The important point is that these approaches do not work in the same way. Probiotics, prebiotics, phytobiotics, organic acids, IgY and bacteriophages target different aspects of the intestinal problem. 

Probiotics: influence the microbial environment^{[1],[2],[3],[4]} 

Probiotics can help limit enteric pathogen colonisation while influencing intestinal and immune responses. Their potential role in NE becomes clearer when looking at their effects beyond simple bacterial replacement. 

Probiotic supplementation increased C. perfringens-specific IgA and reduced caecal C. perfringens levels. Butyricicoccus pullicaecorum reduced intestinal lesion scores and improved growth performance in challenged birds, while Lactobacillus johnsonii enhanced intestinal immune responses. 

For feed planning, this means that the specific probiotic organism matters. Different organisms can produce different effects on microbial balance, intestinal immunity, and NE-related outcomes. 

Prebiotics: Support beneficial microorganisms^[4],[5] 

Prebiotics work through a different route. MOS, FOS, inulin, and arabinoxylans can selectively support beneficial intestinal microorganisms. 

Yeast-derived preparations can also influence the immune environment. Killed yeast cells increased regulatory T-cell responses and IL-10 mRNA while reducing IL-1 mRNA. FOS and MOS increased beneficial microbial diversity and reduced E. coli and C. perfringens levels in the ileum. 

Combining probiotic and prebiotic approaches can also be useful. Probiotic supplementation produced a 30% reduction in NE mortality, while prebiotic supplementation produced a 29% reduction; the reduction reached 39% with in-feed antibiotics in the same comparison. These figures come from the particular feeding and challenge conditions reported and should not be applied as expected mortality reductions for every flock. 

Phytobiotics: Use plant-derived compounds strategically^[4] 

Phytobiotics include plant extracts and essential oils with proposed antimicrobial, antioxidant, anti-inflammatory, and immunomodulatory actions. 

Their effects can extend to the intestinal structure. Improvements in villus height and other measures of intestinal morphology have been reported, together with reduced effects of NE challenge. 

For practical use, however, the plant, active compounds, dose, and formulation matter. Toxicity and interactions also need consideration. A plant-derived additive should therefore be selected for its intended purpose rather than treated as interchangeable with every other phytobiotic. 

Organic acids: Support the intestinal barrier^[4] 

Organic acids, including short- and medium-chain fatty acids, can modify intestinal pH, nutrient utilisation and pathogen growth. 

Their potential value extends beyond microbial control. An organic-acid blend improved serum IgA, feed efficiency, ileal digestibility and footpad health. Improvements in feed conversion, together with less mucosal atrophy and enterocyte necrosis and increased expression of tight-junction proteins, have also been reported. 

This makes organic acids particularly relevant when NE prevention is approached through intestinal health and barrier integrity, rather than pathogen reduction alone. 

IgY and bacteriophages: More targeted approaches 

IgY provides another option. Antibodies obtained from egg yolk can target enteric pathogens and neutralise their effects. Anti-Clostridium IgY improved feed intake and weight gain while reducing morbidity and mortality in infected birds^[4]. Commercial application requires regulatory approval. 

Bacteriophages work differently by targeting susceptible bacterial populations. A phage cocktail improved weight gain and feed conversion and produced a 92% reduction in mortality during an NE challenge^[5],[6]. Other phage preparations reduced intestinal pathology, mortality, caecal bacterial levels, and lesion severity^[5]. 

Choosing the approach at farm level 

The choice of feed-based intervention should follow the problem being addressed: 

• Microbial imbalance: Consider probiotics or prebiotics. 
• Intestinal barrier and gut health: Organic acids may have a role. 
• Plant-derived antimicrobial or immune effects: Phytobiotics can be considered. 
• Targeted bacterial control: Bacteriophages offer a more specific approach. 
• Pathogen-neutralising antibodies: IgY provides another targeted option. 

Clinical Bottom Line 

Feed-based NE control is not about adding another product to the ration and expecting the same response in every flock. The useful approach is to identify the intestinal problem that needs to be addressed and select the feed strategy accordingly. 

Probiotics and prebiotics can work through microbial and immune modulation, organic acids can support the intestinal environment and barrier, phytobiotics can provide multiple biological effects, while IgY and bacteriophages offer more targeted approaches. Used with appropriate feed and flock management, these strategies provide practical tools for reducing the conditions that favour NE when antibiotic growth promoters are not being used.

References:

1. Fathima S, Shanmugasundaram R, Adams D, Selvaraj RK. Gastrointestinal microbiota and their manipulation for improved growth and performance in chickens. Foods. 2022 May 12;11(10):1401. https://www.mdpi.com/2304-8158/11/10/1401
2. Fidanza M, Panigrahi P, Kollmann TR. Lactiplantibacillus plantarum–nomad and ideal probiotic. Frontiers in microbiology. 2021 Oct 6;12:712236. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.712236/pdf
3. Park YH, Hamidon F, Rajangan C, Soh KP, Gan CY, Lim TS, Abdullah WN, Liong MT. Application of probiotics for the production of safe and high-quality poultry meat. Korean journal for food science of animal resources. 2016 Oct;36(5):567-76. https://link.springer.com/content/pdf/10.5851/kosfa.2016.36.5.567.pdf
4. Fathima S, Hakeem WG, Shanmugasundaram R, Selvaraj RK. Necrotic enteritis in broiler chickens: a review on the pathogen, pathogenesis, and prevention. Microorganisms. 2022 Sep 30;10(10):1958. https://www.mdpi.com/2076-2607/10/10/1958
5. Pourabedin M, Guan L, Zhao X. Xylo-oligosaccharides and virginiamycin differentially modulate gut microbial composition in chickens. Microbiome. 2015 Apr 10;3(1):15. https://link.springer.com/content/pdf/10.1186/s40168-015-0079-4.pdf
6. Miller RW, Skinner J, Sulakvelidze A, Mathis GF, Hofacre CL. Bacteriophage therapy for control of necrotic enteritis of broiler chickens experimentally infected with Clostridium perfringens. Avian diseases. 2010 Mar 1;54(1):33-40. https://avian-diseases.kglmeridian.com/downloadpdf/view/journals/avdi/54/1/article-p33.pdf