Nutritional Management of Heat Stress in broiler and layers

Nutritional Management of Heat Stress in broiler and layers

1. Nutritional Strategies to Combat Heat
Stress in Broilers and Layers
Dr. Pankaj Kumar Singh
Professor & Head (Animal Nutrition)
Bihar Animal Sciences University, Patna, Bihar
Contact: 7909079625; E-mail: [email protected]

2. Stress .…?
Stress refers to any condition that affects the biological mechanisms
of the body -human or animal.
(Virden and Kidd, 2009; Cirule et al., 2012)
The word stress has no universal definition.
Stressis a physiological and metabolic responseof the bird to any-
environmental,
nutritional or
management factorthat disrupts its homeostasis, resulting in-
reduced performance,
compromised immunity and
increased vulnerability to disease.

3. Climate Change and Poultry: Rising Heat Stress Risk
Global temperatures have risen by ~1.2°C since the 19th century. (NASA, 2023)
Poultry-dense regions like India, Brazil and Africa face frequent heat waves and >30°C daily temperatures.
IPCC projections: +1.5°C to +2.5°C rise by 2050: increasing heat stress incidents in poultry farms.
Heat stress expected to become a year-round concern in tropical poultry production systems.

4. ColdStress Cold Thermo-Neutral Warm Heat Stress
Less than 10°C 10-18°C 18–24°C 25-29°C Above 30°C
Unableto coop Adjustment Comfort zone Adjustment Exhaustion
Environmental Temperature Vs Heat stress

5. HEAT STRESS
Heat stress occurs when the ambient temperature exceeds the bird's thermoneutral zoneand the bird’s
natural cooling mechanisms(e.g.-panting, vasodilation) are insufficient to dissipate body heat.
Fig: Natural cooling mechanism in poultry.

6. Behaviouralresponses of poultry to heat stress
Increased panting
(Open-beak breathing)
Avoid Crowding
Wing spreading and
Reduced Movement
Reduced feed intakeIncrease water intake Lethargy

7. Physiological responses of poultry to heat stress
1. Activation of the Hypothalamic-Pituitary-Adrenal (HPA) Axis:
The HPA axisis a neuroendocrine system that regulates
stress responses in poultry.
PVN: Paraventricular
Nucleus
CRH: Corticotropin-releasing
hormone
AVP: Arginine vasopressin
ACTH: Adreno-corticotropic
hormone
GCs: Glucocorticoids
System Affected Effect of Corticosterone
Metabolism
↑ Gluconeogenesis, ↑ protein catabolism, ↓
muscle mass
Immune system
Suppression of lymphocyte proliferation,
↓ antibody titers
Behaviour
Altered feeding, increased water intake,
decreased activity
Growth/
Reproduction
↓ Growth hormone secretion,
↓ reproductive performance
Huang et al. (2024)

8. 2. Respiratory Alkalosis from Panting:
System Effect of Alkalosis
Calcium
metabolism
↓ Ionized Ca²⁺ in blood → poor eggshell
quality (especially in layers)
Enzyme activity
pH-sensitive enzymes inhibited → metabolic
inefficiency
Neuromuscular
↑ Nerve excitability → muscle tremors or
spasms (in severe cases)
Electrolyte
imbalance
Disturbed Na⁺, K⁺, and Cl⁻ homeostasis →
dehydration, weakness
Panting increases
Co
2 exhalation
H
+
reduces and pH rises
Acid-base homeostasis disrupts
Respiratory alkalosis is a disruption in blood acid-base balance where the pH becomes abnormally alkaline (>7.45) due to
excessive loss of CO₂ from the lungs during panting which is a significant thermoregulatory response in birds.
Fig: Mechanism of action of respiratory alkalosis
WastiS. et al. (2020)

9. 3. Hyperthermia and Thermoregulatory Failure:
Neurological
Impact
Cardiovascular
Strain
Cellular Stress
and Damage
Metabolic
Disruption
•Increased basal metabolic
rate under stress
•Dehydration, electrolyte
imbalance and acid-base
disorders
•Rapid depletion of muscle
glycogen
•Increased expression
of Heat Shock
Proteins (HSPs)
•Leads to apoptosis or
necrosis in severe
cases
•Peripheral
vasodilation diverts
blood from vital organs
•Reduced cardiac
output: risk of hypoxia.
•Disruption of
hypothalamic control
•Seizures, confusion, or
complete collapse

10. 4. Oxidative Stress and Cellular Damage:
Oxidative stress refers to a condition where the production of reactive oxygen species (ROS) exceeds
the capacity of the body’s antioxidant defenses, leading to cellular and molecular damage.
In poultry, heat stress causes metabolic acceleration and mitochondrial dysfunction, increasing ROS
generation.
Heat stress induces HSPs (Heat
Shock Proteins) to:
Refold denatured proteins
Prevent protein aggregation
Aid in cell survival
However, persistent stress leads
to cell death.
WastiS. et al. (2020)

11. 5. Reduced Feed Intake and Digestive Efficiency:
Hypothalamic appetite
suppression
Birds prioritize reducing
metabolic heat production
(dietary thermogenesis)
over growth.
Heat stress → vasodilation in skin and vasoconstriction in
viscera which causes ↓ Blood flow to gut, liver and pancreas
and impair the production of digestive enzymes.
Mahasnehet al. (2024)

12. Huang et al. (2024)
Broilers exposed to 35°C for 7 days showed:
↓ 30–50% in bursa and thymus weight
↓ 40% in IgG and IgA titers
↑ serum MDA and TNF-α (indicators of
oxidative/ inflammatory stress)
Quinteiro-Filho et al. (2012)
6. Immunological responses of poultry to heat stress
Heat stress causes a shift from immune defense to
survival priorities, mediated by neuroendocrine
and oxidative changes that suppress both innate
and adaptive immunity.

13. Parameter Normal Condition Under Heat Stress
Core body temperature ~106.7°F (41.5°C) >109.4°F (43°C) –can lead to hyperthermia
Ambient temperature range
65–77°F (18–25°C,
thermoneutral)
>86°F (30°C): mild stress
>95°F (35°C): severe stress
Respiration rate (breaths/min) ~30–40 >100 (panting starts >85°F)
Feed intake Normal ↓ 10–30% (significant drop after 86°F)
Corticosterone level Baseline (low) Elevated –primary stress hormone in birds
Oxidative stress markers (e.g., MDA) Low Increased (lipid peroxidation, cell damage)
Immune response (IgG, cytokines) Optimal Suppressed –↑ susceptibility to infections
Productivity Stable growth/egg yield
↓ Growth rate, ↓ egg production, ↑
mortality
Characteristics of Heat Stress in Poultry

14. ↓ Feed Intake:
up to 30%
reduction during
hot periods
(>95°F/35°C)
↓Average Daily
Gain (ADG):
reduced by 20–
35 g/day
↓ Feed
Conversion
Ratio (FCR)
efficiency
↑ Mortality
rate: especially
during severe
heatwaves
↓ Carcass yield:
especially breast
meat and fat
quality
Broiler Production Impacts

15. ↓ Egg
production: by
10–25%
↓ Egg weight &
shell quality
↓ Fertility and
hatchability
(especially in
breeders)
↑ Incidence of
soft-shelled or
cracked eggs
Layer Production Impacts
Cracked eggs
Soft-shelled eggs

16. Eggshell is made up of Calcium carbonate
Calcium carbonate
(Feed)
(Calcium hunger)
(CO2-Respiratory tract)
Duringsummer-Pantingoccurs
MoreamountofCO2isexcretedoutresultinginrespiratoryalkalosis
(HCO3)
Poor egg shell formation
Effect of Heat Stress on Layer Production

17. More egg breakage during summer season
Egg breakage

18. Economic Impacts
India:Layer farms report ~15–20% seasonal losses in summer months.
Global poultry sector loses billions annually due to heat-related production
drops, mortality and feed inefficiency.
Estimated annual global economic loss:
Broiler industry: ~$2.5 to $3 billion
Layer industry: ~$1.2 to $1.5 billion
St-Pierre et al., 2003;
Coble et al., 2014
Stakeholder Economic Impact
Poultry farmers Profit margin squeeze due to potential flock culling
Feed producers Changes in demand for energy-dense and specialized diets
Processors ↓ Product yield and quality : financial losses and recalls
Consumers ↑ Price of poultry meat and eggs due to reduced supply

19. Introduction to Nutritional Strategies
Heat stress alters feed intake, digestion, metabolism and immunity.
Nutritional strategies provide a proactive, non-invasive means to:
Support physiological resilience
Maintain production performance
Reduce mortality and economic loss
Main Objectives of Nutritional Strategies
Increase palatibilityand energy density
Correct blood pH through electrolyte supplementation
Enhance ROS scavenging via vitamins and trace minerals
Support microbiome and intestinal integrity
Mitigate immunosuppression and promote resilience

20. Feed Management during Hot Weather
Decline in feed intake by almost 5% with every degree rise in temperature from 32-38°C.
Feeding should be done during the cooler hours of the morning & evening
1/3
rd
feed during early morning and 2/3
rd
during evening in layers
Increase the number of feeders me to reduce competition among birds.
Feed intake can be increased by wet mash feeding
Feed should be made denser with nutrients:
Usage of vegetable or highly digestible protein sources.
Do not apply a high crude protein level in the formula.
Use oil as energy source
Add linoleic acid to enhances performance and egg weights
Incorporation of Synthetic amino acids
Add antioxidants to reduce heat stress (Vit. E, Vit. C, Selenium).

21. Energy and Protein Adjustment
To maintain caloric intake despite reduced feed consumption.
To reduce heat increment.
Increase dietary energy density using lipids.
E.g.-Vegetable oil, Fish oil etc.
Reduce CP by 1-2% to lower metabolic heat
production.
Supplement digestible essential amino acids to
maintain balance
(DL-methionine, L-lysine Hcl, L-threonine)
Macronutrient
Heat
Increment
(% of GE)
Thermal
Implication
Reference
Fat 5–7%
Preferred energy
source in heat
stress diets
Geraert
et al., 1996
Carbohydrate 10–12%
Moderate
thermogenic
effect
Geraert
et al., 1996
Protein 20–30%
Increases
metabolic heat
load and nitrogen
excretion
Mujahid
et al.,2007

22. Dietary Electrolyte Balance
Heat stress leads to loss of water and electrolytes which disrupts acid-base balance.
Addition of 0.4% KClor 0.4% sodium chloride (NaCl) to broiler drinking
water during summer season improved BW, FI, and FCR.
Water consumption was enhanced by about 20% in birds provided water
containing 6.25 g of sodium bicarbonate per litre.
Electrolyte salts should be added in feed/water:
•NaHCO₃ (sodium bicarbonate): Buffers blood pH, restores Na⁺
•KClor K₂CO₃: Replenishes K⁺
•NH₄Cl(in some cases): Helps counteract alkalosis
Water supplementation:
•Commercial electrolyte powders or solutions (e.g., with Na⁺, K⁺, Cl⁻, Mg²⁺)
•Administer during the hottest parts of the day or before/after heat waves
Brantonet al. (1986)
Dai et al. (2009)
Ideal DEB range during heat stress: 200–300
mEq/kg
Mushtaq et al.(2013)

23. Nutrient Primary Function Optimal Dietary LevelEffect Under Heat Stress Reference
Vitamin E
Lipid membrane protector,
breaks lipid peroxidation chain
200–300 mg/kg
↓ Lipid peroxidation, ↑
immunity and performance
Sahinet al., 2002
Vitamin C
Regenerates Vitamin E, lowers
cortisol, scavenges ROS
250–500 mg/kg
↓ Corticosterone, ↑ stress
tolerance, improved FCR
Lin et al., 2006
Selenium (Se)
Cofactor for glutathione
peroxidase (GPx), synergizes
with Vit E
0.3–0.5 mg/kg (organic
form preferred)
↑ Antioxidant enzyme activity,
↓ oxidative cell damage
Mahmoud and Edens,
2005
Zinc (Zn)
Cofactor for superoxide
dismutase (SOD), DNA
stabilization
40–80 mg/kg (preferably
organic/chelated)
↑ Immune function, ↓
oxidative damage to tissues
Ebeidet al., 2012
Curcumin
Anti-inflammatory, ROS
scavenger, gene modulation
100–200 mg/kg
↓ HSPs expression, ↑
antioxidant enzymes
Durraniet al., 2006
Green Tea
Polyphenols
(EGCG-Epigalo-
catechingallate)
Antioxidant, antimicrobial,
immune-modulatory
100–150 mg/kg (depending
on extract)
↓ Lipid peroxidation, ↑
lymphocyte viability
Yang et al., 2001
Resveratrol
Enhances mitochondrial
function, antioxidant gene
expression
250–400 mg/kg ↓ Oxidative Sahinet al., 2010
Use of Antioxidants in Summer Stress

24. Antioxidants as Cellular Defenders
Hu R. (2019)
Fig: Cellular damage due to Oxidative Stress
Heat Stress
↓
↑ ROS Production
↓
Oxidative Damage to Lipids, Proteins, DNA
↓ ↑
Antioxidant DefenseOverwhelmed
↓
Supplemental Antioxidants
↓
Scavenge ROS
↓
Regenerate Endogenous Systems
↓
↓ Oxidative Damage
↓
↑ Performance & Immunity

25. Optimizing Micronutrients: Vitamins and Minerals in Heat Stress
Supplementing specific vitamins and minerals improves thermotolerance, immune response, productivity,
and survivability.
Increased levels
over NRC
recommendations
during hot
months
Organic
(chelated) forms
are more
bioavailable and
effective under
stress
Water-soluble
vitamins (C, B-
complex) can be
given through
drinking water
Fat-soluble
vitamins (A, D,
E) administered
through feed

26. Additive Mechanism of Action Heat Stress Benefits References
Probiotics
Compete with pathogens, enhance
immunity
↑ Gut integrity, ↓ inflammatory
markers
Mountzouriset al., 2007
Prebiotics Promote growth of beneficial bacteria↑ Microbiota balance, ↓ enteric stressYang et al., 2009
Synbiotics Combined probiotics + prebiotics
Synergistic gut and immune
protection
Awadet al., 2009
Organic Acids
Lower gut pH, improve nutrient
digestibility
↓ Pathogen load, ↑ digestive
efficiency
Adil et al., 2011
Phytogenics
Plant-based bioactives (e.g., essential
oils)
↓ Oxidative stress, ↑ feed intakeWindischet al., 2008
Betaine Osmoprotectant, methyl donor
↑ Thermotolerance, ↓ mortality, ↑ gut
function
Ratriyantoet al., 2009
Enzymes
Enhance nutrient breakdown (e.g.,
NSP, phytate)
↑ Digestive efficiency, ↓ metabolic
burden
Cowiesonet al., 2006
Feed Additives and Their Effects

27. Feed Additives

28. UyangaV.A. (2022)
Betaine
Betaine (trimethylglycine) is a naturally
occurring compound used in poultry diets
for its osmoregulatory, methyl donor and
anti-stress properties, especially under
heat stress conditions.
Betaine supplementation at 1–2
g/kg feed or 0.5–1 g/L water
improves thermotolerance,
growth, and antioxidant status in
poultry under heat stress by
sparing methionine and acting as
an osmolyte.
(Ratriyantoet al., 2009;
Sayed and Downing, 2011;
Eklund et al., 2005)

29. GuanidinoaceticAcid
Guanidinoaceticacid is a natural precursor of creatine, synthesized in
the body from arginine and glycine.
Creatine is then phosphorylated into phosphocreatine, a rapid energy
reserve for ATP regeneration which is crucial during stress and high
energy demand.
Fig: Formation of Creatine via GAA
Broilers under cyclic heat stress (35°C) supplemented with 1.2 g/kg
GAAshowed:
↑ Feed intake and weight gain
↓ Rectal temperature
↑ Breast muscle yield
DeGroot et al. (2019)
GAA at 1 g/kg feed improved antioxidant status (↑ SOD, ↓ MDA) and
growth in heat-stressed birds.
Majdeddinet al. (2021)
Combined GAA and betaine
supplementation reduced mortality
and supported mitochondrial
energy metabolism during chronic
heat stress.
Khalajiet al. (2023)

30. Chromium (Cr) is a trace mineral required in
minute amounts for normal metabolism.
Biologically active form in animals: Trivalent
Chromium (Cr³⁺).
Chromium
Chromium helps counteract heat stress effects by:
Supporting insulin-like activity
Reducing stress hormone secretion
Enhancing antioxidant defenses
Preserving immunity and productivity
Common Chromium
Source
Chemical Form BioavailabilityEffects Under Heat Stress References Dose rate
Chromium Picolinate
(CrPic)
Organic
(Cr³⁺ + picolinic acid)
High
↓ Corticosterone, ↑ antioxidant
enzymes, ↑ FCR and growth
Sahin et al., 2020;
Zha et al., 2023
3 mg/kg
1600mcg/kg
Chromium Yeast
Organic
(Cr bound to yeast
matrix)
Very High
↑ Immunity, ↓ oxidative stress,
↑ insulin sensitivity
Feng et al., 2018 1500 ppb
Chromium Chloride
(CrCl₃)
Inorganic salt Low
Weak performance effects,
↓ absorption and bioavailability
NRC, 1994 30 mg/kg
Nano-Chromium (nCr) Nanoparticle form Excellent
↑ Growth, ↓ stress markers,
↑ insulin-like activity
El-Deep et al., 2022 0.2mg/kg

31. Water Management in Heat-Stressed Poultry
In summer, water consumption goes up 3-4 times feed intake.
Continuous supply of good quality water supply is essential.
Water pipelines must be cleaned well and flushed periodically.
Maintain water pH in acidic conditions (5.5-6).
Ensure that drinkers have sufficient water flow (>70 mL/minute/nipple drinker)
Water is the most critical nutrient during heat stress because:
Poultry lose body water via panting and evaporation.
Water supports thermoregulation, nutrient metabolism and electrolyte balance.
A 10% reduction in water intake may cause 20% reduction in feed intake.

32. Summary of Feeding Management during heat stress

33. Summary and Conclusion
Heat stress is a multifactorial challenge that disrupts physiology, immunity and
productivity in poultry.
Nutritional management is a powerful, practical and scalable tool to mitigate these
effects.
Strategies such as feed reformulation, targeted supplementation and water quality
management significantly reduce the negative impacts.

34. Take Home Message
•Adjust Feed Formulation:
•Increase energy densityand nutrient concentration
•Use highly digestible ingredients
•Supplement synthetic amino acids
•Add Antioxidants & Vitamins:
•Vitamin C, Vitamin E, Selenium, Chromium
•Combat oxidative stress and boost immunity
•Add Additives:
•Probiotics, Prebiotics, synbiotics, essential oils
•Betain
•Maintain Electrolyte Balance:
•Supplement Na⁺, K⁺, Cl⁻, and HCO₃⁻
•Supports acid-base balance and hydration
•Enhance Water Quality & Access:
•Cool, clean water at all times
•Use electrolytes or vitamins in water during peak heat
•Feeding Time Management:
•Offer feed during cooler hours (early morning or evening)

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37. THANK YOU

38. Books

42. Acknowledgments
•Dr. AakriteeKumari, M.V.Sc.Scholar (Animal Nutrition), BVC, Patna
•Dr. AnshulKunal, M.V.Sc. Scholar (Animal Nutrition), BVC, Patna
•ChmbondBioscience Team
•My teachers
•Research Scholars
•Online articles

43. Discussion
43