For decades, many poultry farmers believed that keeping broiler chicks under constant light would make them eat more, stay active, and grow faster. However, recent research and real-farm experiences reveal a surprising truth — darkness doesn’t hinder broiler chick growth.
In fact, controlled dark periods can improve overall health, reduce stress, and even increase feed conversion efficiency (FCR). This blog dives deep into why darkness matters, how to implement it, and the results you can expect — backed by poultry science and field-tested farming practices.
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🔬 1. The Science Behind Darkness and Broiler Growth
How Light and Darkness Affect Physiology
- Melatonin Regulation – Darkness triggers melatonin production, which improves rest, immune function, and stress recovery in broiler chicks.
- Muscle Growth and Repair – Chicks grow during rest as protein synthesis accelerates when the body is in a recovery phase.
- Metabolic Efficiency – Short dark periods allow chicks to digest and utilize feed more effectively, improving FCR without reducing overall growth.
📌 Insight: Studies in poultry physiology show that 16–18 hours of light with 6–8 hours of darkness provides optimal results — balancing activity and rest.
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🍽 2. Feed Conversion and Weight Gain in Darkness
One of the biggest concerns for farmers is whether less light means less feed intake — and therefore slower growth.
Detailed Explanation:
- Night Rest Improves Feed Utilization – Chicks that rest during dark periods digest feed better, absorbing more nutrients from the same amount of feed.
- Reduced Wastage – Overactive chicks in 24-hour light often peck and scatter feed, leading to wastage. Darkness reduces unnecessary movement, saving feed costs.
- Even Growth Rates – Dark periods encourage calmer, more consistent feeding habits, leading to uniform flock weight.
📌 Example: A commercial broiler farm in Pakistan found that 7 hours of darkness per day did not reduce average body weight at 6 weeks — but improved feed cost efficiency by 5%.
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🧠 3. Behavioral Benefits of Darkness
Darkness influences broiler chick behavior, leading to a calmer flock.
Detailed Points:
- Less Aggression – Constant light can overstimulate chicks, leading to feather pecking and fighting. Darkness promotes rest, reducing aggressive interactions.
- Better Sleep Cycles – Chicks establish natural circadian rhythms, improving welfare and lowering stress hormones.
- Improved Mobility – Excess light and constant activity can cause leg strain. Darkness gives joints and muscles time to recover, reducing lameness issues.
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💡 4. Designing the Right Light–Dark Schedule
Different climates and production systems require customized lighting programs.
Recommended Schedules:
- Commercial Broiler Farms: 18 hours light / 6 hours dark for optimal growth and welfare.
- Small-Scale Backyard Systems: 16 hours light / 8 hours dark to save electricity and promote natural behavior.
- Hot Climate Farms: Longer dark periods during midday heat can reduce heat stress and mortality.
📌 Tip: Use dim transition lighting when switching from light to dark to avoid startling the birds.
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🌍 5. Country-Wise Observations & Practices
🇺🇸 United States
Farmers integrating dark periods report reduced mortality rates and better welfare ratings, helping with consumer trust.
🇵🇰 Pakistan
Darkness schedules help manage heat stress, especially during high summer temperatures.
🇧🇷 Brazil
Producers use short dark breaks in between feeding times to encourage rest in intensive broiler systems.
🇮🇳 India
Small-scale farmers use natural day–night cycles to reduce costs without affecting growth.
🇬🇧 United Kingdom
Darkness policies are encouraged as part of RSPCA and welfare-certified poultry programs.
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❤️ 6. Welfare, Stress, and Longevity Benefits
Darkness isn’t just about growth — it’s about the long-term health of the flock.
Detailed Discussion:
- Lower Stress Levels: Dark periods lower cortisol levels, improving immunity.
- Better Heart Health: Overactive birds under constant light can develop cardiac issues.
- Reduced Mortality: Healthier, less stressed birds have lower disease susceptibility.
📌 Welfare-focused farms often receive better prices from retailers and wholesalers for “humanely raised” poultry.
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📈 7. Economic and Sustainability Advantages
- Electricity Savings – Reducing artificial lighting saves power costs.
- Feed Cost Efficiency – Less wastage and better digestion.
- Marketing Advantage – Farms can advertise “animal welfare–friendly” practices to appeal to conscious consumers.
- Reduced Medical Costs – Lower stress means fewer illnesses and veterinary bills.
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📅 Week-by-Week Lighting Guide for Broilers
🐣 Week 1 – Brooding Period (Day 1–7)
Goal: Warmth, comfort, and easy access to feed & water for newly hatched chicks.
Lighting Strategy:
- Hours of Light: 23 hours light / 1 hour darkness (for rest)
- Light Intensity: 30–40 lux near feeders and drinkers
- Reason: Newly hatched chicks need to quickly learn where feed and water are. A brief dark period helps them adapt to rest cycles without stress.
Feeding Tip: Keep feeders well-lit during the light hours. Offer fresh crumble feed every 2–3 hours to encourage early crop fill.
Climate Consideration:
- Hot Climates (Pakistan, Brazil, India): Use warm but not intense lighting to avoid overheating.
- Cold Climates (UK, Northern USA): Ensure light is combined with adequate heating to maintain 32–34°C in the brooder area.
🐥 Week 2 – Transition to Rest Periods (Day 8–14)
Goal: Begin establishing natural day–night cycles.
Lighting Strategy:
- Hours of Light: 20 hours light / 4 hours darkness
- Light Intensity: Reduce to 15–20 lux to encourage calmer behavior.
- Reason: This helps develop circadian rhythms while maintaining high feed intake.
Feeding Tip: Offer main feeding sessions just before dark and right after lights come on — this matches natural poultry behavior.
Climate Consideration:
- In humid areas (Malaysia, Nigeria), dark periods help reduce bird activity during peak humidity, lowering respiratory stress.
🐓 Week 3 – Balanced Growth (Day 15–21)
Goal: Maintain steady weight gain with less stress.
Lighting Strategy:
- Hours of Light: 18 hours light / 6 hours darkness
- Light Intensity: 10–15 lux to avoid overactivity.
- Reason: Birds now know feeding patterns, so more rest improves digestion and muscle growth.
Feeding Tip: Switch to grower feed with balanced protein (18–20%) and ensure water availability during dark hours using low-level dim lights near drinkers.
Climate Consideration:
- Tropical regions – Introduce darkness during midday heat to prevent overheating.
- Cold climates – Maintain stable temperature; sudden light changes can stress birds.
🐓 Week 4 – Rapid Growth Phase (Day 22–28)
Goal: Maximize weight gain while maintaining welfare.
Lighting Strategy:
- Hours of Light: 18 hours light / 6 hours darkness
- Light Intensity: Maintain 10 lux — bright enough to find feed but low enough to promote calmness.
- Reason: Growth hormones work best when birds rest adequately during darkness.
Feeding Tip: Offer feed in short intervals during light hours; avoid overfilling feeders to prevent waste.
Climate Consideration:
- In high rainfall seasons (Philippines, Indonesia), more dark hours at night reduce dampness-related activity, lowering risk of footpad dermatitis.
🐓 Week 5 – Pre-Finishing (Day 29–35)
Goal: Maintain optimal feed conversion ratio (FCR) and uniformity.
Lighting Strategy:
- Hours of Light: 16–18 hours light / 6–8 hours darkness
- Light Intensity: 5–7 lux, allowing rest and minimal movement at night.
- Reason: Birds are at peak growth; dark periods prevent stress-induced weight variation.
Feeding Tip: Use pellet feed for better FCR and ensure fresh, clean water at all times.
Climate Consideration:
- In hot dry areas (Middle East, Northern Africa), dark periods during afternoon heat significantly reduce mortality.
🐓 Week 6 – Final Growth & Processing Readiness (Day 36–42)
Goal: Achieve processing weight with minimal health issues.
Lighting Strategy:
- Hours of Light: 16 hours light / 8 hours darkness
- Light Intensity: 3–5 lux for night rest, slightly brighter (10 lux) during light hours.
- Reason: Full rest helps birds retain weight and reduces last-week stress.
Feeding Tip: Maintain high-energy finisher feed; avoid sudden changes in feeding patterns to prevent digestive upset before slaughter.
Climate Consideration:
- In cold climates (Canada, Russia), keep heaters running during dark hours to maintain stable weight gain.
🌍 Why This Lighting Program Works in Different Countries
- USA & UK: Welfare regulations encourage dark periods — this program meets those standards.
- Pakistan & India: Dark hours during midday heat help prevent mortality and heat stress.
- Brazil & Malaysia: Reduced light intensity prevents stress-related health issues in humid tropical climates.
- Nigeria & Kenya: Dark periods help conserve electricity while maintaining growth rates.
🔑 Key Takeaways & Practical Farming
- Darkness improves feed efficiency without affecting growth.
- Rest periods reduce stress and mortality in broiler flocks.
- Customized lighting schedules are essential for different climates and farming systems.
- Country-specific adaptations can improve profitability while meeting welfare standards.
✅ Conclusion: Darkness Is a Growth Ally, Not an Enemy
Modern poultry farming needs to balance productivity, welfare, and sustainability. The evidence is clear — darkness does not hinder broiler chick growth when managed correctly. Instead, it improves feed efficiency, welfare, and overall farm profitability.
For farmers still running 24-hour light schedules, now might be the time to rethink your lighting strategy — your flock and your bottom line will thank you.