Clinical manifestation and prevention and control measures of heat stress in pigs

In the hot summer months, the herd is prone to heat stress. Simply speaking, after the body is stimulated by high temperature, the body is in a state of nervous alert, which leads to changes in various functions and metabolic functions.

猪群热应激的临床表现及防控措施

1. Causes of heat stress in pigs

Under normal circumstances, the heat generated by the body during metabolism is mainly emitted by evaporation, conduction, radiation and convection, thus maintaining the balance of heat production and heat dissipation in pigs. The pigs, especially the sows, boars and big fat pigs, have thick skin and sweat glands are not developed. The heat generated in the body cannot be regulated by evaporation. Relatively speaking, the heat dissipation is slow, and the excess heat accumulates in the pigs, resulting in a series of pigs. Abnormal performance, which is the internal cause of heat stress in the herd. In addition, many pig farms have poor cooling facilities, high density of feeding, and unfavorable cooling of pig houses. The temperature of pregnant sows and fattening pig houses is as high as 37 °C, and the high temperature has become an external cause of heat stress in pig farms.

2. The mechanism of heat stress in pigs

2.1 heatstroke

High temperature and high humidity in summer, the pigs live in this environment, the metabolism is strong, the heat production is more, the heat is less, the body heat is accumulated, the body water loss is increased, and then the metabolic acidosis is caused. In severe cases, it may even be manifested as heart failure and central nervous system. Neurological dysfunction, clinical manifestations of clinical symptoms of heat stress.

2.2 day sickness

The summer sun is relatively large. If the shading effect of the pig house is not ideal, the head of the pig group is exposed to direct sunlight. The sun will cause overheating and congestion of the meninges and brain parenchyma of the herd. The internal pressure rises to produce an inflammatory reaction and cause lesions. The central nervous system is impaired, and the clinical manifestations are clinical symptoms of heat stress.

猪群热应激的临床表现及防控措施

3. Clinical manifestations of heat stress in pigs

Acute heat stress: often sudden onset, sick pigs with depression, rapid heartbeat, shortness of breath, elevated body temperature, conjunctival flushing, hot skin touching, conjunctival cyanosis. Severely ill pigs are convulsed, their limbs are stroked, and in severe cases they die within a few minutes.

Chronic heat stress: a, boar libido weakened, ejaculation decreased, sperm motility decreased. b. The ovarian function of the empty sow is reduced, the estrus is delayed, the hidden estrus is not even estrus, and the conception rate is decreased. c. Pregnancy sows undergo heat stress within 8 days after breeding, which may lead to a large number of embryonic deaths; heat stress in late pregnancy may cause reproductive problems such as partial abortion in sows, resulting in litter size and litter size. Reduction. d. The feed intake of lactating sows decreased after delivery, the amount of lactation decreased, the growth of piglets was poor, and the survival rate decreased.

4. Comprehensive prevention and control of heat stress in pigs

1) Strengthen the construction of cooling hardware

For the high temperature in summer, the pig farm will use various cooling measures to cool down, but the pig farmers must select the corresponding cooling facilities according to the characteristics of the pig house to achieve the desired cooling effect.

a. The wet curtain cools down. The cooling of the wet curtain is to use the clean water to pass through the wet curtain at one end of the pig house, and the negative pressure is generated by the fan at the other end, and then close the door and window to force the air to enter the pig house through the wet curtain, thereby achieving the cooling effect. This method is suitable for pigs at all stages. The use of wet curtains can reduce the temperature in the pig house by about 5 °C, but the disadvantage is that the humidity in the pig house is high.

b. Spray to cool down. By spraying water in the pig house, the water mist will accelerate the heat dissipation of the skin and reduce the body surface temperature, and the water evaporation can also take away some of the heat to achieve the cooling effect. However, this method also causes the humidity in the pig house to be too large, which is more suitable for use in the fattening house.

c. Air conditioning cooling. Whether it is spray cooling or wet curtain cooling, its cooling effect is limited. If the ambient temperature is too high, the effect is not ideal. The only cooling effect is air conditioning, but considering the high cost of air conditioning, it is recommended that the sow delivery room and public The pig house is cooled by air conditioning.

2) Supply sufficient clean drinking water

Because the body has no sweat glands on the body surface, its cooling mainly relies on respiratory evaporation and heat dissipation to increase heat dissipation. Therefore, when the temperature is high, the pigs need to drink plenty of water to help lower the body temperature, and the lower the drinking water temperature, the more heat is removed from the pigs, and the cooling effect is better.

3) Strengthen feeding management

According to clinical experience, high-density breeding will increase the heat stress of the herd, so the stocking density should be reduced as much as possible to prevent heat stress. In the summer, the feed formula should be properly adjusted to increase the nutrient concentration of the feed. For example, adding about 2% vegetable oil to the feed while reducing the use of the fiber raw material, and reducing the crude protein level in the feed while satisfying the requirement of essential amino acids, To relieve heat stress. Then, when feeding in summer, you should choose a cool season in the morning and evening, avoiding the hot season at noon. It is recommended to feed before 8 o'clock in the morning and after 6 o'clock in the evening. If the feed intake during the day is small, you can strengthen the feeding once at 12 o'clock in the evening.

4) Use anti-heat stress drugs

Currently, drugs that are effective against heat stress include vitamins, electrolytes, baking soda, and some Chinese herbal medicines. When the temperature in the pig house exceeds 35 °C, attention should be paid to the prevention and control of heat stress. The commonly used drug regimen is as follows:

猪群热应激的临床表现及防控措施

a. Add vitamin C or vitamin E to feed or drinking water;

b. Add soluble amino group to the drinking water;

c. Add baking soda to the feed;

d. Chinese herbal extracts using Bupleurum Oral Liquid + Silver Yellow Soluble Powder in drinking water, or Chinese herbal medicine powder powder such as Yuqicao Powder and Tongxinlian Powder;

e. Adding Chinese medicines such as hawthorn, dried tangerine peel, divine song, and atractylodes spleen to appetite and heat and heat to improve the pig's feed intake and heat stress resistance.

5. Treatment of heat stress in pigs

Western medical law: It is found that heat-stressed pigs should be quickly transferred to a cool and ventilated place, and physically cooled using cold water toppings and ice cubes. Intramuscular injection of 10% sodium camphorsulfonate injection 5 ml twice a day. The ear vein was bled with 200 ml, and intravenously instilled with 5% glucose saline 250 ml or so, and injected once every 5 hours.

Chinese medicine method: It is found that heat-stressed pigs should be quickly transferred to a cool and ventilated place, and physically cooled using cold water toppings and ice cubes. Houttuynia 100g, wild chrysanthemum 100g, dried tangerine peel 25g, light bamboo leaves 100g, After 1000 ml of Jianshui, take it once. Or use 20-30 ml Chaihu oral solution for oral administration to improve the symptoms of heat stress.

After reading so much about the heat stress treatment of pigs, how do the pig farmers know how to deal with these situations?

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