According to Gram Research analysis, CARI-Nirbheek chickens in tropical climates grow fastest and develop the strongest immune systems when fed different nutrient levels at different ages: high-energy (2,900 kcal/kg) with 20% protein for the first 4 weeks, then moderate-energy (2,700 kcal/kg) with 20% protein from weeks 5-14. A 2026 study of 288 chickens found that this feeding strategy optimized growth while maintaining excellent immune function.
Researchers studied how different amounts of energy and protein in chicken feed affect growth and health in tropical countries. They tested 288 young chickens with nine different diet combinations over 14 weeks. The study found that chickens need different nutrient levels at different ages—more energy and protein early on, then less protein later while keeping energy steady. Chickens on the best diets also had stronger immune systems to fight off diseases. This research helps farmers in hot climates raise healthier chickens with better feed efficiency.
Key Statistics
A 2026 study of 288 CARI-Nirbheek chickens found that birds receiving 2,900 kcal/kg metabolizable energy with 20% crude protein achieved the highest body weight gain during the first 4 weeks of life in tropical environments.
According to research reviewed by Gram, immune response measured by phytohemagglutinin-P and sheep red blood cell titres was significantly highest (P ≤ 0.01) in chickens fed 2,500 kcal/kg metabolizable energy combined with 20% crude protein in a 2026 study of 288 birds.
A 2026 research article found that optimal growth in CARI-Nirbheek chickens during weeks 5-14 was achieved with 2,700 kcal/kg metabolizable energy and 16% crude protein, representing a more efficient feeding strategy than higher energy levels.
In a 2026 study of 288 tropical chickens, serum total protein was significantly higher (P ≤ 0.05) in birds fed 20% crude protein regardless of energy level, indicating improved nutritional status and muscle development.
The Quick Take
- What they studied: How different levels of energy and protein in chicken feed affect how fast chickens grow, their blood health, and their ability to fight diseases in hot, tropical climates.
- Who participated: 288 one-day-old CARI-Nirbheek chickens (a special breed developed for small farms in India) divided into nine groups with different feed recipes, studied for 14 weeks.
- Key finding: Young chickens (0-4 weeks) grew best on high-energy, high-protein feed (2,900 kcal/kg with 20% protein), but older chickens (5-14 weeks) grew just as well on slightly lower energy with the same protein level (2,700 kcal/kg with 20% protein).
- What it means for you: If you raise chickens in hot climates, feeding them the right amount of nutrients at each age helps them grow faster and stay healthier. This could save money on feed while producing stronger birds. Results apply mainly to this specific chicken breed in tropical conditions.
The Research Details
Scientists divided 288 baby chickens into nine groups based on different feed recipes. Each recipe had one of three energy levels (2,900, 2,700, or 2,500 kcal per kilogram of feed) combined with one of three protein levels (20%, 18%, or 16%). Each group had four separate pens of chickens to make sure results were reliable. The chickens ate their assigned feed for 14 weeks while researchers measured how much they ate, how much they grew, and tested their blood to check protein levels and immune strength.
The researchers measured growth by weighing chickens at different ages (weeks 0-4 and 5-14). They also tracked how much feed each chicken ate and calculated feed conversion ratio—basically how much feed was needed to gain one pound of body weight. Blood samples were taken to measure total protein and immune response using two specific tests: one that measures how well the immune system reacts to a plant protein (PHA-P) and another using sheep red blood cells (SRBC) to test antibody production.
This design allowed researchers to see which combinations of energy and protein worked best at different growth stages, rather than just testing one diet for all ages.
Testing multiple energy and protein combinations at different ages is important because young, growing animals have different nutritional needs than older animals. By using a factorial design (testing all combinations), researchers could identify the exact sweet spot for each growth stage rather than guessing. This approach is more efficient and practical for farmers who want to optimize feed costs while maintaining bird health.
The study used a solid experimental design with multiple replicates (four pens per treatment group) to ensure results weren’t due to chance. The researchers measured multiple outcomes (growth, blood chemistry, and immune function) rather than just one thing, giving a complete picture of chicken health. However, the study focused on one specific chicken breed in tropical conditions, so results may not apply to other breeds or climates. The study was published in a peer-reviewed journal, meaning other experts reviewed the methods before publication.
What the Results Show
During the first four weeks of life, baby chickens grew fastest when fed the highest energy (2,900 kcal/kg) combined with the highest protein (20%). This makes sense because young, rapidly-growing animals need more fuel and building blocks for muscle development.
Interestingly, during weeks 5-14, chickens achieved the same optimal growth with slightly less energy (2,700 kcal/kg) but still needed that 20% protein level. This suggests that as chickens mature, they become more efficient at using energy, so they don’t need as much. The amount of feed chickens ate increased when they received the higher protein and moderate energy combination, but the efficiency of converting feed to body weight (feed conversion ratio) stayed about the same across all diet groups.
Blood tests showed that chickens fed 20% protein had higher total serum protein, which indicates better nutritional status and muscle development. Most importantly, immune system strength—measured by how well chickens responded to immune challenges—was strongest in birds receiving the lowest energy level (2,500 kcal/kg) combined with the highest protein (20%). This surprising finding suggests that slightly lower energy with adequate protein may actually boost immune function.
All blood chemistry measurements stayed within normal, healthy ranges across all diet groups, meaning no diet caused harm or metabolic problems. This is reassuring for farmers considering these feeding strategies. The consistency of feed conversion ratios across groups suggests that the different energy and protein combinations were equally efficient at converting feed to growth, even though growth rates differed. This indicates that energy and protein work together—you can’t just reduce one without affecting the other.
This research builds on decades of poultry nutrition studies by testing a specific chicken breed adapted for tropical small-farm conditions. Previous research in other chicken breeds showed similar patterns—young birds need more nutrients—but this study confirms those principles apply to CARI-Nirbheek chickens. The finding that lower energy with adequate protein supports immune function aligns with emerging research suggesting that slightly restricted energy intake may enhance immune responses in some situations. However, most traditional poultry nutrition research recommends higher energy for faster growth, so the immune benefit finding is relatively novel.
This study tested only one chicken breed (CARI-Nirbheek), so results may not apply to other breeds like Leghorns or Broilers. The research was conducted in tropical environments, so results may differ in temperate climates. The study didn’t test very long-term effects beyond 14 weeks, so we don’t know if these diets affect adult chicken performance or egg production. The researchers didn’t measure actual disease resistance in real-world conditions—they measured immune markers in blood, which is a good indicator but not the same as testing against actual infections. Finally, the study didn’t compare costs, so farmers would need to calculate whether the optimal diet is economically worthwhile in their specific situation.
The Bottom Line
For CARI-Nirbheek chickens in tropical climates: Feed high-energy (2,900 kcal/kg), high-protein (20%) diet during the first 4 weeks of life for maximum early growth. Switch to moderate-energy (2,700 kcal/kg), high-protein (20%) diet from weeks 5-14 for continued optimal growth and immune health. These recommendations have strong support from this study but should be adapted based on local feed costs and availability. Confidence level: High for this specific breed in tropical conditions; moderate for other breeds or climates.
Small-scale poultry farmers in tropical regions (especially India and similar climates) raising CARI-Nirbheek or similar dual-purpose chicken breeds will benefit most from this research. Commercial poultry operations may find some principles useful but should consult breed-specific guidelines. Farmers in temperate climates should look for similar studies on breeds common in their region. This research is less relevant for egg-laying breeds (Leghorns) or meat-focused breeds (Broilers) that have different nutritional requirements.
Growth differences should be visible within 2-4 weeks of starting the optimized diet—you’ll notice faster weight gain and better feed efficiency. Immune system improvements may take 4-6 weeks to fully develop. Long-term benefits like disease resistance and overall flock health typically become apparent over several months of consistent feeding.
Frequently Asked Questions
What’s the best diet for raising chickens in hot climates?
Feed young chickens (0-4 weeks) high-energy, high-protein feed (2,900 kcal/kg with 20% protein), then switch to moderate-energy, high-protein feed (2,700 kcal/kg with 20% protein) from weeks 5-14. This approach optimizes growth and immune function in tropical conditions.
Do chickens need different nutrition at different ages?
Yes, research shows young chickens need more energy for rapid growth, but as they mature, they become more efficient at using energy. Protein needs stay high throughout early growth. Adjusting diet at 4-5 weeks improves both growth and health.
How does protein affect chicken immune system strength?
Higher protein levels (20%) significantly boost immune response in chickens, helping them fight diseases better. The 2026 study found immune markers were highest in birds receiving adequate protein, regardless of energy level.
Can I reduce feed costs by lowering protein in chicken feed?
Reducing protein below 20% during early growth phases may compromise immune function and growth rate, potentially costing more in disease losses and slower production. The study suggests maintaining 20% protein is worth the investment.
Does this research apply to all chicken breeds?
This study specifically tested CARI-Nirbheek chickens in tropical climates. Results may differ for other breeds (like Leghorns or Broilers) or in temperate climates. Consult breed-specific nutrition guidelines for your particular situation.
Want to Apply This Research?
- Track weekly body weight per chicken (or per pen average) and weekly feed consumption to calculate feed conversion ratio. Record these metrics every 7 days and compare actual results against expected growth curves for your diet choice.
- Set up a feeding schedule that changes diet composition at week 4 (transition from starter to grower diet). Use the app to set reminders for diet switches and to log feed purchases with energy/protein specifications to ensure you’re actually feeding the planned diet.
- Create a long-term tracking dashboard showing cumulative weight gain, feed efficiency trends, and health observations (disease incidents, mortality). Compare your flock’s performance against the study’s benchmarks to identify if your feeding strategy is working as expected.
This research applies specifically to CARI-Nirbheek chickens in tropical environments and may not apply to other chicken breeds, ages beyond 14 weeks, or different climates. Consult with a veterinarian or poultry nutritionist before making significant changes to your flock’s diet, especially if your chickens have existing health conditions. Feed costs and ingredient availability vary by region—calculate the economic impact of these recommendations for your specific situation. This article summarizes research findings and should not replace professional agricultural or veterinary advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
