Heat stress

1. Mohamed Nabeh
DVM,MSC,PhD Poultry diseases
AHRI-Egypt
+201004181378
mdvet2006@gmail.com

15. reduced feed intake (−16.4%)
Lower body weight (−32.6%)
Higher feed conversion ratio
(+25.6%)
Decreased the proportion of breast
muscle
reduction of 28.58 g/bird, resulting
in a 28.8% decrease in egg
production.
31.6% reduction in feed
conversion, 36.4% in egg
production, and 3.41% in egg
weight eggshell thickness, and
increased egg breakage.

17.  Environment
 House management
 nutritional management

19. Weather forecast

20.  Orientation
 Insulation
 Water system
 Litter
 Stocking density
 Ventilation

27.  Energy and Protein in Feed :
 • Stimulation of feed intake in heat stress
improves weight gain but mortality also
increases.
The heat increment with protein catabolism is
more than that of carbohydrates and fat.

28.  Reduction in protein in diet to reduce heat
increment
 Increases feed intake, due to the deficiency
of amino acids.
• Less protein in diet also reduces water intake
Under heat stress conditions,
feed formulation based on the digestible
amino acids

29.  Energy
 Increasing the ME content of feed also
improves energy intake.
 The increased energy intake results in
improved growth but also in increased fat in
the carcass and also the mortality.
 Fats/oil are good in summer because their
heat increment value is lowest give better
cooling
 Effect in body because of higher water
content and fat stimulates feed consumption
 Fat should be increased by 2 to 3%

30.  Feed consumption increased up to 17% by
5% fat supplementation in heat stressed
birds because fat improves palatability.
Water consumption will be 4:1in hot climate

31.  Vitamins
 Electrolytes
 Minerals
 Others supplementation

32.  Anti-oxidation vitamins( anti-stress)
 Vitamin C
 Vitamin E
 Vitamin C
 Decreasing synthesis and secretion of
corticosteroids, vitamin C alleviates the negative
effects of stress. vitamin C enhances antioxidant
activity of vitamin E.
increases to 250-400 mg ascorbic acid/kg
 improvements in livability, feed intake, egg
production and egg quality with dietary ascorbic
acid.

33.  Primary antioxidant in biological systems and
break the chain of lipid peroxidation in cell
membranes (Increase upto 250-500 mg)
 Vitamin A upto 15000 iu
 Vitamin D3 increase
 Vit K increase
in heat stress
blood clotting time is prolonged

34.  Panting increases carbon dioxide loss in the
bird
Effects
 increase water intake
 aids in keeping a constant body temperature

35.  Electrolytes maintain ionic and water balance in the
body.
Broiler growth is affected when blood pH is
 below 7.2 and above 7.3.
 During heat stress electrolytes are lost from the
body.
 Increased respiration rate during heat stress also
results in C02 loss and acid-base alterations.

36.  Acid base balance is influenced by the degree and
duration of thermal stress and acclimatization.
During panting excessive loss of carbon dioxide (CO2)
occurs, resulting in reduced partial pressure of carbon
dioxide (CO2) in blood plasma.
 The bicarbonate buffer system lowers the
concentration of hydrogen ion, increases plasma pH
and plasma bicarbonate levels.
 The respiratory alkalosis may start at 350 C and
becomes severe the rise in temperature.

37.  Dietary electrolyte balance (DEB), under
practical considerations, is considered with
sodium (Na+), potassium (K+) and chloride
(CI-).
 D E B ( m E q / k g Feed) = (( % Na / At wt(23) +
% K/At wt(39.1)- %C1/Atwt(35.5)) x 10000).

38. A DEB of 240-250 m E q / kg feed
adequate for broilers under normal and heat
stressed conditions.
 • The relationship ((K+Cl)/Na>1) has to be
maintained always.
High DEB (e.g. 340) results in metabolic
alkalosis and low DEB (e.g. 100) in metabolic
acidosis.

39. Mineral excretion is usually increased
 Calcium ( increases)
 Zinc (organic )
key mineral element of this critical enzyme.
 Copper (organic )

40.  Time of feeding
 Heat increment is associated from the time of
feeding up to about 4-6 hours after feeding.
 Survivability of the bird will increase by feeding the
birds during night and withdrawing the feed from
about 4-6 hours before the initiation of heat stress.
 Forum of pellet
Pellet quality

41. Osmoregulation
 Betain
 Suppression of growth can be partially alleviated
by supplementation of
 1% NH4Cl
 0.15% - 0.6% KCl
 0.2% NaHCO3.

42.  Acidifier
 Probiotic
 Antimycotoxin
 Heat stress can induce unfavorable changes in
indigenous bacterial microbiota. Supplementation
of probiotic lactobacillus strains may enrich
diversity of microbiota and restore microbial
balance in jejunum & caeca of chicken.
 Reduce harmful effects

43. Anticoccidials
Nicarbazine and Monensin are contraindicated
in summer.
Nicarbazine decreases tolerance to heat and
Monensin depresses water intake.

44. Any question?

45. Thank you