Poultry nutrition has long been recognized as one of the most crucial elements in efficient broiler farming. While protein levels, energy content, and micronutrient balance are all essential, one often-overlooked but equally significant aspect is the diameter of pellet feed. At first glance, pellet size may seem like a trivial detail, but research shows that it can drastically affect feed intake, digestion efficiency, growth rate, and even mortality levels.
At the International Poultry Science Forum (IPSF), a series of empirical studies were presented that linked pellet diameter to broiler performance across different growth phases. This comprehensive blog will examine the role of pellet size in maximizing flock uniformity, improving the feed conversion ratio (FCR), and ensuring healthier, faster-growing birds. We will also include insights from feed mill technology experts, poultry scientists, and real-world farm case studies from around the globe.
🔬 The IPSF Study: Methodology and Scientific Observations
Study Design
The flagship IPSF study was conducted across several controlled poultry housing environments using Ross 308 broilers over a full 42-day production cycle. The birds were randomly divided into four groups based on pellet feed diameter:
- Group A: 2.0 mm pellets
- Group B: 3.0 mm pellets
- Group C: 4.0 mm pellets
- Group D: 5.0 mm pellets
Other variables—diet composition, housing temperature, lighting, and management practices—were kept constant to isolate the effect of pellet size.
Key Observational Parameters:
- Feed Intake (FI): measured daily
- Body Weight Gain (BWG): tracked weekly
- Feed Conversion Ratio (FCR): calculated as feed consumed divided by weight gained
- Carcass Yield: measured post-slaughter
- Mortality Rates: tracked to correlate with pellet acceptance and digestion issues
Core Findings:
- 3 mm and 4 mm pellets yielded optimal FCR and uniform flock performance.
- Birds fed with 2 mm pellets exhibited slower early growth and lower feed intake.
- 5 mm pellets led to increased feed rejection and higher mortality in early weeks due to choking or under-digestion.
- Pellet quality (durability and uniformity) played a crucial role in maximizing efficiency across all sizes.
📅 Phase-by-Phase Guide to Pellet Diameter Optimization
🐣 Starter Phase (Day 0–14)
Young chicks have delicate digestive systems and small beaks. Their preference is for finely crumbled feed or micro-pellets.
- Recommended Size: 2.5 mm – 3.0 mm
- Justification: Easier pecking, reduced energy spent eating, faster digestion
- Note: Crumble uniformity is essential to avoid selective feeding
🐥 Grower Phase (Day 15–28)
The birds develop stronger beaks and improved digestive enzyme activity. Transitioning to a slightly larger pellet size promotes better gut development.
- Recommended Size: 3.5 mm – 4.0 mm
- Justification: Enhances gizzard function and nutrient assimilation
- Case Insight: A Brazilian commercial farm reported a 7% improvement in BWG using 3.8 mm pellets over 3.0 mm
🐓 Finisher Phase (Day 29–42+)
Larger broilers can handle coarser pellets, but care must be taken to avoid oversized feed that may reduce intake.
- Recommended Size: 4.0 mm – 5.0 mm
- Justification: Supports maximum gut fill and reduces sorting behavior
- Pro Tip: Maintain pellet durability to prevent excessive fines, which reduce intake
🧪 Physiological Effects of Pellet Size on Broilers
1. Digestive Tract Maturation
Appropriate pellet size stimulates gizzard development, resulting in stronger contractions and better mechanical breakdown of feed.
- Improved digestion: Reduces undigested feed in excreta
- Enhanced nutrient bioavailability: Better amino acid absorption and enzyme utilization
2. Behavioral Feeding Efficiency
Pellet size impacts the pecking behavior and time spent eating. Birds consuming smaller-than-ideal pellets expend more energy to achieve satiety.
- Time-at-feeder: Smaller pellets increase feeding time
- Energy cost: Larger but manageable pellets reduce unnecessary energy loss
3. Gut Microbiota Balance
Pellet texture and size influence the retention time of feed in the digestive tract. Longer retention encourages better fermentation and microbiota colonization.
- Healthier gut flora: Supports immunity and growth
- Reduces enteric disorders: Especially during transition phases
🌍 Regional Trends and Case Studies
🇺🇸 United States
Several large-scale farms in Georgia and Arkansas reported improved ROI after shifting to phased pellet sizing. Farmers used precision milling equipment to create feeds ranging from 2.8 mm to 4.2 mm during the cycle.
🇵🇰 Pakistan
Due to equipment limitations, most feed mills provide uniform pellet sizes year-round. Transitioning to phased sizing improved FCR by 5–8% in pilot studies.
🇧🇷 Brazil
A leading poultry integrator in Brazil implemented a pellet-sizing matrix in its feed manufacturing SOP. They observed fewer wet litter problems and better uniformity.
🏭 Feed Mill Engineering Considerations
To successfully implement size-based feed formulation, poultry feed mills should:
- Invest in variable-die pellet mills
- Regularly check durability index (88–95%)
- Adjust crumbler gap settings precisely for starter feeds
- Monitor moisture content to prevent microbial spoilage
Tip: Automation of pellet sizing improves consistency and allows mid-batch changes without downtime.
📊 Broiler Performance Benchmarks Based on Pellet Diameter
| Pellet Size (mm) | Avg. Daily Gain (g) | FCR | Mortality (%) |
|---|---|---|---|
| 2.0 | 55–60 | 1.65 | 4.2 |
| 3.0 | 63–68 | 1.52 | 2.3 |
| 4.0 | 64–70 | 1.49 | 2.1 |
| 5.0 | 61–65 | 1.58 | 3.5 |
🧠 Final Thoughts
Pellet size optimization is an underutilized yet highly impactful strategy in modern poultry production. As the IPSF data shows, matching pellet size with the bird’s age and development improves feed efficiency, lowers mortality, and supports uniform flock growth.
With rising input costs and pressure for sustainability, feed manufacturers and broiler producers alike must focus on maximizing nutritional value—not just with ingredient quality but also with physical form and size.
Investing in pellet variability, monitoring field performance, and adapting to regional climates and genetics will place your operation at the forefront of poultry productivity.