Preparing poultry for heatwaves

To help birds survive heatwaves, they should not only be kept under the best possible living conditions, but their water-electrolyte metabolism should also be supported. Environmental changes would streamline the thermoregulation processes, and adequately selected feed additives would prevent water and electrolyte loss.

Paulina Abramowicz-Pindor, PhD
Department of Research and Development
AdiFeed Co Ltd.

Poultry house temperature, together with other microclimatic factors such as humidity, air velocity, concentration of harmful gases like NH3, CO2, H2S, light intensity and dust significantly affect the poultry’s health and productivity. Keeping an adequate air temperature in the poultry house to prevent the overheating of birds is particularly important in the summer season. A too high ambient temperature increases their sensitivity to pathogens present in the environment, such as bacteria and fungi, and risks their bodies overheating (hyperthermia). For broiler chickens, commercial laying hens, and parent flocks of broiler chickens and turkeys, the optimal temperature range is between 15-25ºC. The ambient temperature exceeding 27-30ºC can cause heat stress in the birds. The consequences of this heat stress in laying hens include reduced egg yield and thinner eggshells due to impaired calcium ion transport and elevated blood pH values. In broiler flocks, a reduced live weight gain of up to 20g was observed and attributed to reduced feed consumption. The mortality rate increases too, and it most frequently concerns the heaviest birds. In the birds’ environment, unfavorable changes also occur, with litter humidity increasing because of dilution of droppings due to higher water consumption. That, in turn, can cause an increase in relative air humidity, which in a poultry house should not exceed 65-70%. All the factors mentioned exert a significant influence on the productivity in poultry farms during periods of high ambient temperatures.

Birds have developed several thermoregulation mechanisms that protect them against both excessive heat loss and overheating. The dissipation of the excess heat produced due to metabolic processes and movement occurs through the skin and respiratory tract. The difference in temperatures between the bird’s skin and environment, e.g., a building’s walls, floor or ceiling, makes it possible to radiate the heat accumulated in the body. By raising their wings, birds increase radiation from less feathered body surfaces. Too high stocking density hinders heat exchange between birds and the environment, which reduces the effectiveness of radiation.

In adequately ventilated rooms, birds can also lower their body temperature through convection, i.e. heat dissipation; this is caused by air movement and temperature difference between air pumped into the building and the air surrounding the birds. The most important factor is air velocity in the building, which depends on the birds’ external temperature and body mass. The value of that parameter on hot days should be around 2-2.5 m/s for birds kept on litter, and 2 m/s for those in cages. These metrics should provide air exchange levels, on hot days, at 8 m³/h. This calculation is for one kg of live weight and should enable complete air exchange in the building during heatwaves within a minute.

Under optimal humidity conditions (40-70%), birds can cool down their bodies through water evaporation from the surface of the mucosa and respiratory tract, which is visible as panting. If the air humidity is too high in the facility, it hinders heat dissipation by the body and creates favourable conditions for growing pathogens dangerous to their health. Panting eliminates on average 540 calories per gram of evaporated water, which should be considered when calculating feed energy demands for hot days. During panting, an excessive loss of carbon dioxide occurs via the lungs, leading to alkalosis – an increase in blood pH value. The frequently used misting or evaporation panels, with constant relative humidity monitoring, enable air cooling without causing excessive damping of the litter. In absolutely no case should the litter, walls or birds be hosed down with water.

Heat loss also occurs through conduction, which is when a body comes in contact with cold air, moist and cold litter or a cold water supply system, or while drinking water of a lower temperature than the body or by inhaling cooler air.

The above-mentioned mechanisms are often insufficient and result in the overheating of birds. During hyperthermia, a significant acceleration of metabolism occurs with a simultaneous loss of water. This leads to dehydration and disorders of the metabolism of minerals (potassium, calcium, phosphorus) and acidosis or alkalosis. A poorly working excretory system retains products of metabolism harmful to birds’ health, thus impairing their overall health condition; because of this, water-electrolyte metabolism disorders and reduced excretion of water via the kidneys are observed. The animals develop leg muscle contractions, comatose states, blood thickening and a tendency towards embolism. A dramatic weight loss occurs, and the mortality rate of the birds significantly increases.

To help birds survive heatwaves, they should not only be kept under the best possible living conditions, but their water-electrolyte metabolism should also be supported. Environmental changes would streamline the thermoregulation processes, and adequately selected feed additives would prevent water and electrolyte loss.

• An air velocity of 8m3/h/kg per live weight of birds should be maintained;
• Access to drinking water (stocking density);
• There should be twice the amount of cold water (10-12ºC) available than usual;
• If possible, the feed availability hours should be changed to morning and evening;
• A higher concentration of feed components with a reduction of raw protein concentration (to be supplemented with synthetic amino acids);
• Adequate levels of minerals (E, D, K, A) and vitamins (B) in feed and water;

To exchange a part of the energy supply to carbohydrates for energy from fats (reduced heat production by the organism).

In the prevention and treatment of water-electrolyte metabolism and acid-base balance disorders, mineral salt solutions combined with plant extracts are important. Such a combination of components is justified since herbal extracts contain easily absorbable bio-elements reducing water and electrolyte losses. An addition of phytocomponents, e.g., flavonoids, anthocyanins, carotenoids, chlorophyll, saccharides, sugar alcohols, amino acids, organic acids and vitamins, support electrolytes’ activity in the regulation of the body’s water metabolism.

adiVigoSOL® PF works in multiple ways, like eliminating the consequences of malabsorption syndrome, leading to diarrhea and dehydration. Tannins in the treatment reduce intestinal oedema by constricting the dilated gastrointestinal blood vessels, thus preventing water loss and the development of inflammatory conditions. Vitamin C, flavonoids and tannins all promote cell membrane integration while also inhibiting inflammation and pain mediators, reducing the effects of stress in the birds.

Flavonoids, anthocyanins and phenolic acids effectively prevent embolism and thrombus formation and improve blood circulation. By using adiVigoSOL® PF, you can contraindicate the frequently recommended administration of salicylates during heatwaves to reduce the risk of infarctions or embolism. On the one hand, salicylates eliminate blood thickening but on the other, they can cause tissue bleeding, and in the case of developing acidosis, they can intensify it. They also cause mucosal hyperaemia (blood accumulation under mucous membranes), which leads to the entry of pathogenic micro-organisms and infections during or shortly after heatwaves. adiVigoSOL® PF also contains similar ingredients to Ringer’s solution. It’s rich in components preventing the development of acidosis and hypertonic dehydration (a higher loss of water than electrolytes) and isotonic dehydration (simultaneous loss of water and electrolytes). It also retains water in blood and lymph and prevents chloride loss. The liquorice extract in adiVigoSOL® PF has similar properties and simultaneously protects the hepatocytes. Saponins, acids and essential oils improve kidney function and clean the urinary tract of mineral-organic deposits and pathogens.

Plant extracts constitute sources of easily absorbable minerals: potassium, silicon, calcium, phosphorus, iron and magnesium. Proper absorption of water and electrolytes is only possible when the intestinal villi have the correct structure (an effect of butyric, valeric and succinic acids), and the putrescent processes in the gastrointestinal tract are limited due to minerals (like iron) and short-chain fatty acids.

Green tea, mint and sage extracts enhance appetite and restore proper gastrointestinal tract functioning (intestinal peristalsis, digestion and absorption). Furthermore, they stimulate the activity of birds in seasons with high temperatures and increase their appetite. Valeric acid, contained in the treatment, stimulates birds to drink water and feed regularly. It also exerts bacteriostatic and anti-fungal effects and prevents stress and neuroses while regenerating damaged intestinal villi. Other components, like saponins and succinic acid, bind harmful metabolites and remove them from the body. So adiVigoSOL® PF not only regulates the water-electrolyte metabolism, preventing dehydration, but also cleans the body enabling a return of homeostasis (internal equilibrium of the living organism).

The field tests and observations conducted in poultry farms and with veterinary doctors have confirmed the multidirectional effects of adiVigoSOL® PF. The product administered to broiler chickens in the summer season, caused, apart from higher water consumption, the maintenance of satisfactory feed conversion. In controlled facilities (with air exchange at levels up to 5 m²/h/kg live weight) the broilers only consumed the feed according to the standards up to 29.5ºC. At 30ºC, a significant reduction in feed consumption by broilers was observed. Above 33.5ºC, the birds were panting, significantly reducing their activity, and stopped moving in the poultry house. When the temperature in the poultry house exceeded 35.5ºC, the mortality rate of broilers due to overheating dramatically increased, reaching as high as 10% of the population daily. In the testing facilities where the product was used, tolerance of the highest temperature increased by 3ºC. The chickens were properly foraging up to the temperature of 33ºC. No increased rate of mortality was observed even after exceeding 35ºC. A significant reduction in deaths during transportation to the poultry abattoir was also observed. Eighty deaths were observed in the control group, compared with only three in the experimental group.

adiVigoSOL® PF, administered to broiler chickens and turkeys during and after treatment with chemotherapeutics, significantly accelerated the birds’ return to everyday water consumption and growth. The treatment was more effective in the flocks where the product was used. Some differences were also observed in the anatomical appearance of the kidneys on pathological examination, and in the experimental group, practically no renal failure was observed. In practice, the administration of the treatment always translated into better productivity.

Considering the numerous causes of loss of body homeostasis, which is particularly harmful in the heatwave periods, it is worth focusing on the multidirectional support of water-electrolyte metabolism in birds. adiVigoSOL® PF supplements body fluids, and provides normal functioning of all organs, particularly the kidneys, liver and pancreas. It increases water consumption and enables maintaining normal fodder consumption, which translates into better economic results, while reducing the mortality rate and increasing production performance in broiler chickens and turkeys.