Strategies for dealing with heat stress in poultry

Strategies for dealing with heat stress in poultry

Strategies for dealing with heat stress in poultry

In the article “Strategies for Addressing Thermal Stress in Poultry,” we explore this topic. The high performance and efficient conversion of modern poultry have resulted in a sensitivity to thermal stress compared to previous generations. Hot weather is considered one of the significant stressors in poultry. Thermal stress results from the combined effects of air temperature, humidity, radiant heat, and air speed, with air temperature playing a more prominent role.

The optimal temperature for laying hens is between 19-22°C, while for broiler chickens during the growth phase, it is between 18-22°C Celsius. When the required temperature for poultry is not met, thermal stress occurs.

Selection for Increased Heat Tolerance

Selection for increased heat tolerance in modern poultry is due to the higher growth rates compared to older strains, which may result in greater sensitivity to heat stress. This leads to a decrease in feed consumption and an increase in water intake. Due to the negative correlation between heat tolerance and high growth rates, as well as low heritability estimates, a practical program for commercial genetic selection is not currently available.

However, by selecting in warm environments, it is possible to improve the heat tolerance of broiler chickens. Although this type of selection may lead to a reduction in growth potential at high temperatures.

Nutritional Strategies (Amino Acid Composition and Protein Levels)

Nutritional strategies (amino acid composition and protein levels) have a significant impact on the growth performance and meat yield of broiler chickens at high temperatures. An optimal amino acid balance at high temperatures alters protein digestion and absorption of amino acids, increasing catabolism and gluconeogenesis during thermal stress in chickens, although this is not clearly defined.

Nonetheless, increasing the balance of amino acids, particularly essential amino acids, may help reduce heat stress levels and lessen detrimental effects at high temperatures. Conversely, an imbalanced diet in amino acids can lead to increased nitrogen excretion in manure, resulting in ammonia accumulation in the air, affecting performance and comfort for the chickens.

Feeding Strategies (Selective Nutrition, Maintenance, Moist Feed, and Pellet)

Feeding strategies (selective nutrition, maintenance, moist feed, and pellet) result in a temporary increase in feed consumption during high-temperature conditions. If feed intake coincides with rising temperatures, it leads to a decrease in overall feed consumption.

At higher temperatures, this effect lasts for about 4 to 5 hours after feed intake, potentially continuing for another 8 to 10 hours. Protein-rich diets generate the highest heat production, and the heat stress effect gradually increases as daily temperatures rise.

During a 16-hour light cycle, birds consume about 40% of their daily feed intake in the morning hours. Additionally, about 30% of the natural diet consists of concentrated protein, which can be consumed during cooler hours of the day. In the remaining hours, they can feed on grains, allowing them more flexibility to meet their daily energy needs. Maintenance feeding is another approach to counteract heat stress, helping birds maintain stable blood glucose levels.

Balancing energy derived from carbohydrates with energy from fats improves birds’ survival capacity. The byproducts of fasting, such as ketones and fatty acids, assist in maintaining pH levels in birds during respiratory alkalosis.

Another method involves moist feeding, which increases the intake of dry matter (DM) and, due to its relative effects on heat stress, leads to higher feed consumption and improved performance in laying hens.

Feeding with a diet containing 50% moisture results in increased dry matter consumption at elevated temperatures. Research indicates that pelleted feed does not significantly affect food consumption but does enhance digestibility, water intake, and egg production in birds under heat stress.

Environmental Strategies: Alternating Light, Appropriate Humidity, EHC, EFR

Environmental strategies, including alternating light, appropriate humidity, EHC (Early Heat Condition), and EFR (Early Feeding Restriction), lead to a reduction in production heat in poultry during thermal stress. The effect of humidity is dependent on age and the ambient temperature. When poultry is exposed to temperatures above 28°C, and broilers are at temperatures exceeding 30°C, issues can arise. High body temperature in one-week-old chicks can lead to a situation where elevated temperatures cause a redistribution of heat within the body and prevent heat transfer from the body to external surfaces.

Increasing temperature during early life (EHC) is one of the factors that can enhance the bird’s tolerance during later stages of growth, making the birds more resilient to high temperatures. In this method, chicks aged 3 to 5 days are kept at a high temperature (36°C) for 24 hours.

Early dietary restrictions have shown positive effects on reducing thermal stress in poultry. Dietary restrictions in chicks can lead to a 60% reduction in thermal stress responses at ages 4, 5, and 6 days, along with strengthening the immune system and improving performance, enhancing the response to thermal stress in the later stages of growth. Additionally, early feeding restrictions (EFR) can be applied alongside increased temperatures during early life (EHC), resulting in improved heat tolerance in birds.

Choosing long-term strategies in reform programs, such as using growth hormone genes and breed genetics, can facilitate dietary strategies to reduce negative effects of thermal stress through controlled feed intake, water balance, and electrolytes, or through enhancing micronutrients like vitamins and minerals to meet specific needs during critical periods of effective thermal stress. However, it seems that increasing heat tolerance in birds through elevated temperatures during early life or early dietary restrictions is a hopeful management approach for enhancing short-term heat tolerance in poultry.

Yektadam Persian is a producer of various types of concentrates and supplements for poultry, livestock, and aquaculture with the highest quality, ready to assist you.

For more information regarding livestock and poultry supplements, please contact Yektadam specialists.

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