As global temperatures rise, heat stress has become a nightmare for poultry farmers worldwide. For broiler chickens—bred for fast growth and high meat production—extreme heat is particularly devastating. Their vigorous metabolism, lack of sweat glands, and dense plumage make them highly sensitive to temperature spikes, leading to poor feed intake, stunted growth, and disrupted fat metabolism. The result? Significant economic losses for the industry. But a groundbreaking study from Nanjing Agricultural University offers new hope: dimethyl itaconate (DI), a natural metabolite derivative, could be the solution to combat heat stress in broilers.
The Heat Stress Crisis in Broiler Farming
Heat stress isn’t just uncomfortable for chickens—it’s a metabolic disaster. When temperatures soar above 30°C, broilers struggle to regulate their body temperature, triggering a cascade of problems:
- Reduced feed intake and weight gain (average daily gain can drop by 20% or more)
- Abnormal fat accumulation in the liver and abdomen
- Imbalanced hormones (e.g., elevated stress hormones like corticosterone)
- Disrupted lipid metabolism, leading to fatty liver and poor meat quality
For farmers, these issues translate to lower productivity, higher feed costs, and compromised flock health. Traditional solutions—like ventilation or cooling systems—are often expensive and energy-intensive. This is why researchers have been searching for safe, cost-effective feed additives to help broilers cope with heat stress naturally.
Enter Dimethyl Itaconate (DI): A Promising Natural Solution
Itaconate, a metabolite produced in the body’s immune cells, is known for its anti-inflammatory and antioxidant properties. But its strong polarity makes it hard to penetrate cell membranes, limiting its use in animal feed. That’s where dimethyl itaconate (DI) comes in. As a cell-permeable derivative of itaconate, DI retains all the biological benefits of its parent compound while being easily absorbed by chickens.
Previous studies showed DI could reduce inflammation and oxidative stress in mammals, but no one had tested its effects on poultry—until now. The team at Nanjing Agricultural University, led by researchers Longlong Li and Haitian Ma, set out to investigate whether DI could protect broilers from heat stress-induced harm. Their findings, published in the Journal of Animal Science in 2023, are nothing short of revolutionary.
The Groundbreaking Study: How DI Protects Broilers from Heat Stress
Experimental Design
The researchers tested 120 21-day-old Ross 308 broilers (a popular commercial breed) divided into five groups:
- Control group: Raised at a comfortable 21°C and fed a standard finisher diet.
- Heat stress (HS) group: Exposed to 32°C for 8 hours daily (mimicking summer heat) and fed the standard diet.
- HS + DI groups: Exposed to the same heat stress but fed diets supplemented with 50mg/kg, 150mg/kg, or 200mg/kg of DI.
The trial lasted 21 days, with the team measuring key metrics like growth performance, fat deposition, hormone levels, and gene expression to assess DI’s effectiveness.
Key Findings: DI Delivers Multiple Benefits
1. Boosts Growth Performance
Heat stress severely reduced the broilers’ final body weight, average daily gain (ADG), and average daily feed intake (ADFI). But DI supplementation turned things around:
- Broilers fed 50-200mg/kg DI gained significantly more weight than the heat-stressed group.
- The 200mg/kg DI dose was most effective at restoring feed intake.
- Even the lowest DI dose (50mg/kg) improved feed conversion ratio (FCR), meaning chickens used feed more efficiently.
2. Reduces Harmful Fat Deposition
Heat stress causes abnormal fat buildup in the liver and abdomen—bad news for both chicken health and meat quality. DI solved this problem by:
- Lowering liver weight and abdominal fat percentage (by up to 19% compared to the HS group).
- Reducing lipid droplets in the liver (visible via Oil Red O staining).
- Lowering levels of triglycerides (TG), total cholesterol (TC), and non-esterified fatty acids (NEFA) in the liver and serum.
3. Balances Hormone Levels
Heat stress disrupts the endocrine system, increasing stress hormones (corticosterone) and insulin while decreasing thyroid hormone (T3)—key regulators of metabolism. DI:
- Reduced corticosterone and insulin levels, easing stress on the body.
- Restored T3 levels, helping to normalize metabolism.
- Lowered elevated thyroxine (T4) levels, correcting hormonal imbalance.
4. Regulates Lipid Metabolism Genes
At the molecular level, heat stress flips a switch: it ramps up genes that promote fat synthesis (e.g., ACLY, ACC, FASN) and shuts down genes that break down fat (e.g., ATGL, CPT-1). DI reversed this trend by:
- Suppressing the overexpression of fat-synthesis genes.
- Boosting the expression of fat-breakdown and oxidation genes.
5. Activates the AMPK Signaling Pathway
The secret behind DI’s success? It activates the AMPK pathway—a key “energy sensor” in cells that regulates metabolism. Heat stress inhibits AMPK activity, but DI:
- Increased the expression of AMPKα1 (a critical gene in the pathway).
- Enhanced the phosphorylation of AMPK and ACCα (proteins that drive fat breakdown and suppress fat synthesis).
In short, DI helps broilers “fight back” against heat stress by rebalancing their metabolism at the cellular level.
Why This Matters for Poultry Farmers
This study is a game-changer for several reasons:
- First of its kind: It’s the first research to prove DI works as a feed additive to relieve heat stress in poultry.
- Safe and natural: DI is a derivative of an endogenous metabolite, meaning it’s less likely to cause side effects compared to synthetic additives.
- Cost-effective: Adding DI to feed is a low-cost solution compared to upgrading farm cooling systems.
- Dosage flexibility: Doses between 50-200mg/kg are effective, with 200mg/kg offering the best overall results.
For farmers struggling with summer heat, DI could mean healthier flocks, better growth rates, and higher profits—all while reducing reliance on energy-intensive cooling methods.
Future Directions and Considerations
While the results are promising, the researchers note a few areas for further study:
- Optimal dosage: More research is needed to pinpoint the exact DI dose that delivers the best results in different broiler breeds and farming conditions.
- Long-term effects: The trial lasted 21 days, so long-term studies are needed to confirm DI’s safety with extended use.
- Broader applications: Could DI help other poultry species (like layers or turkeys) cope with heat stress? Future research will tell.
Final Thoughts
Heat stress is a growing threat to global poultry production, but dimethyl itaconate offers a natural, effective solution. This study from Nanjing Agricultural University not only advances our understanding of how to protect broilers from heat stress but also provides a practical tool for farmers to improve flock health and productivity.
As the climate continues to change, innovations like DI will be crucial for building resilient, sustainable poultry farms. Whether you’re a large-scale producer or a smallholder, keeping an eye on DI as a feed additive could be one of the best decisions you make for your flock—and your bottom line.