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One article to take you to quickly understand the poultry heat stress!

Category: Technical Information

Heat stress occurs frequently in poultry animals during the high temperature season. Today we will talk about the heat stress content of chickens.


What is heat stress?

Heat stress is the sum of non-specific responses of humans or animals to stimuli that exceed their own thermoregulatory capacity.

The chicken is a warm-blooded animal with its own isothermal zone. The comfort zone of laying hens is 13 ℃ ~ 27 ℃, and the ambient temperature of maximum feed efficiency is 24 ℃ ~ 27 ℃. The maximum growth rate of broilers is 10 ℃ ~ 22 ℃, and the best feed efficiency is 27 ℃.

When the ambient temperature is within the isothermal zone of the chicken, it maintains its normal body temperature through its own body temperature regulation mechanism; if the ambient temperature continues to rise, the heat dissipation capacity of the chicken is blocked, and the thermal balance cannot be maintained only by physical regulation. At this time, physical and chemical regulation must be initiated. When these adjustments can not effectively maintain the thermal balance in the body, the body will produce a series of reactions, which will reduce the production performance of poultry and endanger the health of the body.

What are the effects of heat stress?

1. Increased oxidative stress in the body. The excess free radicals produced during oxidative stress can damage tissue components of the cell, including proteins, lipids, and DNA.

2, acid-base imbalance. Poultry lack sweat glands, heat loss is mainly through panting evaporation, the higher the temperature, the more dependent on breathing heat dissipation, resulting in respiratory alkalosis and metabolic acidosis.

3) Reduced immunity. Therefore, in the hot summer, infectious and infectious poultry diseases have faster transmission rates and higher infection rates. In addition, some inflammation-related cells increase in number.

4, neuroendocrine changes caused by a series of hormonal changes, is the root cause of the decline in growth performance and reproductive efficiency; at the same time, production efficiency will be greatly reduced.


In addition to the above negative effects, we next focus on the impact of heat stress on the intestine.

The effect of heat stress on the intestine?

1. Intestinal morphology and function are affected

Under heat stress conditions, morphological and physiological changes in the intestinal epithelium negatively affect the function and integrity of the intestinal epithelium, impair the integrity of the intestinal tract, and increase susceptibility to diseases such as Salmonella.

Heat stress can also affect intestinal permeability due to the destruction and alteration of tight junction proteins.

This, coupled with increased levels of pro-inflammatory cytokines, stress hormones (cortisol), and reactive oxygen species, results in poor nutrient absorption and poor production performance.

2, increased permeability, may lead to "intestinal leakage"

Both acute and chronic heat stress increase intestinal permeability, in part by increasing oxidative stress and interfering with the expression of tight junction proteins.

Heat and oxidative stress in the intestine can lead to intestinal cell damage and apoptosis.


When the tight junction barrier is broken, substances within the lumen can seep into the blood stream, forming what is known as an "intestinal leak".

At the same time, it causes abnormal cell apoptosis, leads to epithelial tissue damage, destroys the integrity of the intestinal barrier, and increases intestinal permeability. The influx of bacterial products from the intestinal lumen into the circulatory system affects organ systems.

Intestinal permeability increases, which facilitates the transfer of toxins and pathogens from the intestine to the bloodstream.


3, changes in intestinal microbes

In addition to increased intestinal permeability, heat stress also affects gut microbial populations. Heat stress causes the proliferation of harmful bacteria and reduces the proliferation of beneficial bacteria.

It leads to imbalance of intestinal flora, increased intestinal permeability, and immune and metabolic dysfunction.

Pathogens such as Clostridium perfringens, Salmonella and coliforms increase under heat stress, while the number of beneficial bacteria such as Lactobacillus and Bifidobacterium decreases.


4. Increased risk of necrotic enteritis

Heat stress can lead to the disorder of intestinal microbiota, the destruction of intestinal integrity, the change of intestinal villi morphology and the problem of immune suppression.

These changes increase intestinal permeability, cause immune and metabolic dysfunction, lead to reduced digestibility and absorption capacity of poultry feed, and increase the risk of necrotic enteritis outbreaks.

Intestinal inflammation impedes nutrient absorption and affects weight gain in animals.


How to avoid intestinal problems caused by heat stress?

From the above, it can be known that the main symptoms of heat stress are to cause intestinal mucosal barrier dysfunction, inflammatory reaction, and an increased risk of bacterial translocation from the intestinal lumen into the blood, and imbalance of intestinal flora.

How to deal with these intestinal problems? Need to do a good job of prevention in advance.

First of all, in terms of breeding management, provide appropriate ventilation for the number of chickens in the poultry house; Adjust the position of the fan, optimize the wind speed and promote air circulation; Reduce the feeding density; Do a good job in the heat insulation facilities of the chicken house to avoid solar heat accumulation; Use evaporative cooling pads or atomizing nozzles; While maintaining the balance of water and electrolyte, do a good job in hygiene management and clean the poultry house regularly.

Today's sharing of the content about poultry heat stress is over. Thank you for reading.