July1 , 2022

Effect of Heat on Egg production



Effect of Heat on Egg production


Heat Stress


Air movement creates a cold air effect, and the body senses a temperature drop due to the air Flow.

“Flocks that have not been previously acclimated to high temperatures are the ones with the greatest loss of productivity and mortality “

Effect of heat stress on the eggshell quality
The flocks of layers under heat stress often lay eggs having thinner and weaker eggshells due to an acid/base disturbance which takes place in the blood as a result of panting (hyperventilation, gular reflux).

When birds hyperventilate to shed body heat, there is an excessive loss of CO2 gas in the lungs and blood. Decrease of CO2 gas in the blood causes the blood pH to rise or become more alkaline. This condition is known as respiratory alkalosis.

Increasing the level of blood pH decreases the activity of the enzyme carbonic anhydrase, which results in a reduction of calcium and carbonate ions transferred from the blood to the Shell gland (uterus). Increasing diet calcium will not correct this problem.

Another contributing factor to thin eggshell is the decrease in calcium consumption as a result of reducing food consumption and escalating loss of phosphorus.

Restoring the acid/base balance

Potassium chloride, ammonium chloride, or sodium bicarbonate (2–3 kg/MT of feed) can replace the lost electrolytes during heat stress and promote water consumption. It has been shown that these treatments are useful to reduce mortality in flocks affected by acute heat stress.

Management of the drinker system for a flock affected by heat stress
During high ambient temperature times, the flock has high water consumption requirements. The water – food consumption ratio is normally from 2:1 at 21°C, but it is increased to 8:1 at 38°C.

For flocks affected by heat stress there must be as much available drinking water as needed.
Make sure drinkers have a suitable water flow (> 70 ml/minute/ nipple drinker).

Make sure drinkers work correctly and provide enough space.
For flocks bred on the floor, providing additional drinkers might help balance the water consumption increase.

Fresh water can help reduce the birds’ core temperature, and hence reduce the impact of heat stress.
Purging water lines in the afternoon helps cool water down and this has been shown to enhance food consumption and sustain egg production in a lot of layers affected by heat stress.

Plastic lines are quickly heated by ambient temperature, making it difficult to cool water below the air temperature, particularly near the ends of long water lines.

Keeping water at a temperature below 25°C helps maintain a greater water consumption, thus causing a greater food consumption. A water temperature above 30°C will have a negative impact on water consumption, and it will also adversely affect food consumption.
Use vitamins and electrolyte supplements in drinking water to compensate the loss of sodium, chloride, potassium, and bicarbonate in urine. Supplementary electrolytes work best when they are used before a sudden rise of ambient temperature.

Drinking water is heated when tanks are directly exposed to sunlight. Such tanks must be light colored, be insulated, and be covered to avoid direct exposure to sunlight. Ideal water tanks are those placed within the barns, or those installed underground.

“Heat stress-affected layer flocks lay eggs with thinner and weaker eggshells due to the blood acid/base balance disturbance as a result of panting “

Management of a flock affected by heat stress

Do not disturb the chickens during the hottest hours of the day or early evening). Adapt work schedules and lighting schedules such that the routine chores are performed early morning or at night.

Management practices which require handling the fowls, such as beak trimming, transport, and vaccinations (via a drop into the eye, the wing surface, or by injection), should not be performed early morning.

Use misters and vaporizers to enhance evaporative cooling during the day. Turn on the misters for 2 minutes every 10 minutes. Misting schedules must be adjusted based on the temperature and humidity within the barn.

Misting at the air inlets of negative pressure ventilation systems has a suitable cooling effect.
Using ceiling sprayers during extremely high temperatures can remove heat from the ceiling and cool the barn inside.

Adjust thermostats such that fans work throughout the night and early morning. The purpose of this is maximizing the cooling inside the barn during the night and prolong the mild temperature period until the next morning.

Increase air circulation in open barns by means of fans. Assure a speed of 1.8–2.0 meters/second where the chickens are.

Caged in birds are more susceptible to heat stress because they are unable to look for a cooler area, and inside the cages they have a lesser chance of shedding heat by conduction. The temperature inside the cage can be much higher than the ambient temperature measured along the aisles. An increase of air speed among cages enhances los of heat by conduction and removes the air entrapped among the birds

Do not work feeders during the hottest time of day.
Avoid having too many cages; cages containing too many birds prevent air from flowing among the birds, thus diminishing the performance of ventilation and increasing the heat load in the barn.

Transport birds early morning or at night. Place fewer birds in each crrier case and keep empty cases in the truck to make room for ventilation around the birds during transport.

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