Practical technical points for heatstroke prevention and cooling in summer chicken raising

The most suitable temperature for laying hen production is 17°C to 28°C, and the temperature range with little effect on production is roughly 7°C to 27°C. When summer temperatures in Shandong generally exceed 35°C, chickens will faint, and when they reach 40°C, chickens will die. Experiments have shown that when the temperature inside the chicken house reaches above 30°C, rooster sperm decreases, hen sexual maturity is delayed, the fertilization rate drops by 60%, and laying by laying hens generally declines. At the same time, due to a drop in blood calcium and an imbalance in acid-base balance, other diseases are easily induced, such as E. coli and mycoplasma disease. Because broiler chickens are large in body size, prone to fat deposition and have difficulty dissipating heat, their tolerance to heat stress is even worse. Therefore, in high-temperature summer weather, if effective heatstroke prevention and cooling measures are not taken, mild cases will lead to reduced production performance, and severe cases will result in heatstroke and death. The following measures can be taken for heatstroke prevention and cooling:

I. Cooling the chicken house surface

1. Experiments have shown that in high summer temperatures, under direct sunlight, a white surface temperature is only 41.5°C, while a black surface can reach 80°C, because a white roof can radiate out 70% of the heat as radiant heat. To lower the temperature inside the house, the roof can be treated with white lime or white cement.

2. Spraying water on the roof can effectively reduce the increase of heat inside the house. Generally, spray water before high temperatures arrive (9:00 to 10:00) and keep it moist.

II. Strengthen ventilation

It is generally required that at high temperatures, the air speed inside the house should reach more than 1 m/s, which can make the perceived temperature drop by more than 3°C. Perceived temperature = air temperature - 3 x (v refers to air speed). The following measures can be taken to strengthen ventilation inside the house:

1. Increase the ventilation openings of the chicken house;

2. Increase the number of exhaust fans;

3. Reduce the cross-sectional area inside the house: Shandong chicken houses mostly use transverse ventilation, so the span of the chicken house should be in the range of 6 to 8 m in order to obtain a good ventilation effect.

4. Night ventilation: if the temperature can drop by 10°C to 15°C at night during high temperatures, the chickens' tolerance to daytime high temperatures will be greatly enhanced.

III. Improve the external environment of the chicken house

Plant trees and grass around the chicken house. Trees can provide shade, grass can absorb heat. Ground with grass can absorb 80% to 90% of heat, with only 20% to 10% reflected out, while the opposite is true for places without grass.

IV. Heatstroke prevention and cooling measures inside the chicken house

1. Set up water curtains or circulating curtains at the air inlet.

2. Set up spray equipment to spray cold water inside the house (it is best to add an appropriate disinfectant to the water, such as Dabeinong Weikang, at a ratio of 1:1000 to 1500). This can directly cool and cool by evaporation, and can also disinfect while chickens are present, but the relative humidity inside the chicken house must not exceed 50%.

3. "Little White Dragon cooling method": that is, use nylon pipes for irrigating farmland, coiled inside the house (9:00 to 10:00 in the morning), filled with cool water, which can effectively lower the temperature inside the chicken house. Chickens can also lie on the pipes, which is very comfortable.

4. Keep the water in the trough sufficient, and the water depth should be adequate: when the house temperature reaches above 28°C, for every 1°C increase, the chicken's water intake must increase by 10 ml per day, so sufficient water must be provided. The deeper the water in the trough, the easier it is for chickens to dip and wash their heads and stay cool. According to staff at the poultry research institute of the University of Texas in the United States, keeping the heads of laying hens cool during high-temperature seasons can increase the laying rate, so where conditions permit, a cold-air cooling device can be set up at the chickens' heads to improve their production performance.

V. Improve feeding management

1. Appropriately adjust the basal diet: carbohydrates are the main source of heat in the chicken body. Under high-temperature conditions, an appropriate amount of fat can be used to replace an equal amount of carbohydrates, which can significantly improve heat stress and poultry production performance.

2. Adjust the feeding method: when the house temperature is above 25°C, for every 1°C increase, the chicken's feed intake decreases by 1.7%, so in high-temperature weather, feed during the cool morning and evening, and provide drinking water during the high-temperature period at noon.

VI. Drug-based heatstroke prevention

1. Add 1.5 to 2 g of VC per kg of feed, which can inhibit the rise in body temperature, increase feeding, and has an anti-heat-stress effect.

2. Use 0.1% sodium bicarbonate for drinking water, which can regulate the acid-base balance in the body. In hot summer, chickens breathe faster to expel excess body heat, causing excessive CO2 excretion, and the carbonate ions (CO3-2) in the blood decrease. The main component of eggshells, CaCO3, cannot be fully guaranteed, thereby causing a decline in eggshell quality and an increase in soft-shelled eggs and white-shelled eggs. Baking soda (NaHCO3) can play a role in supplementing CO3-2. The general dosage is between 0.1% and 0.5%, but the amount of salt fed should be reduced accordingly to prevent ingesting too much sodium ions. For example, at an air temperature of 30°C and a relative humidity of 65%, NaHCO3 0.25% and salt 0.2% are appropriate.

3. Adding 0.1% fumaric acid to the diet can have a sedative effect, reduce activity, lower metabolism, and reduce heat production in the body.

4. Adding 70 PPm of salinomycin to the diet (70 g per ton of feed) can stabilize the laying rate, prevent heat stress, and also prevent and control coccidiosis.

5. Add Dabeinong Weilikang to drinking water (100 g mixed with 200 kg of water) to supplement nutrition, improve body immunity, and reduce the impact of heat stress.

VII. Emergency measures when chickens suffer heat stress

1. Place them in a ventilated and shaded place;

2. Wash them with water, especially the head.