Prevention and Treatment of Heat Stress in Sows in Summer and Injection Methods

Pigs are homeothermic animals with thick subcutaneous fat and underdeveloped sweat glands, so they dissipate heat slowly and are very intolerant of heat. In summer, heat stress easily affects the reproductive performance of sows, so how should it be dealt with? If heat stress occurs, what injection should be given? Let's take a look together below.

I. What is heat stress

1. It is the sum of various nonspecific physiological responses made by the pig's body to a high-temperature environment.

2. “Stress” refers to an adaptive response made by the organism itself to adversity when facing pressure such as changes and adverse conditions. Stress is a series of complex life activities related to the “nervous system, endocrine system, and immune system, etc.” Stress is unavoidable, and the extent of the damage is related to the pig's own adaptability.

II. What symptoms are there

Rapid breathing (panting), reduced feed intake (a sudden sharp drop or even complete refusal to eat), a large increase in water intake, frequently playing with water, liking to lie on wet ground (for example, rolling and lying in feces and urine), reduced activity (even lying on the side without moving for a long time), listlessness (even completely ignoring changes in the surroundings), reddening of the skin, and elevated body temperature.

III. What harm does heat stress do to sows

1. The most suitable ambient temperature for sows is 19°C. After exceeding 30°C, the mating rate drops by 20%, pregnant pigs are prone to miscarriage and stillbirth, and if they still have not farrowed after 114 days, the mortality rate increases.

2. Heat stress affects estrus and conception rate in sows. Studies have shown that under high-temperature conditions, the average age at first estrus of gilts is delayed by 22 days, and when the temperature is above 28°C, sexual maturity in sows is delayed. The time for weaned sows to resume estrus after weaning is longer in July-September than in other months. The conception rate is also lower in summer, and as the temperature continues to rise, the conception rate gradually declines.

3. It affects the survival rate of sow embryos. The strong stress effect of high temperature causes endocrine dysfunction in sows, also strengthens peripheral blood circulation, reduces the blood supply inside the body, affects protein synthesis, causes insufficient embryonic nutrition, and leads to early embryonic absorption and death, thereby significantly reducing the number of piglets born. In addition, high temperature can also cause many adverse changes in the intrauterine environment, increasing stillbirths and deformed fetuses.

In addition, heat stress also affects the number of piglets born to sows and affects the nursing performance of sows, reducing milk yield and lowering feed intake in sows, so that pregnant sows cannot take in enough nutrition, resulting in a lack of strength during farrowing.

IV. How to deal with heat stress in sows

1. Improve the raising environment

Strengthen shading, ventilation, and heat-insulation facilities in the pig house, such as building shade shelters, planting trees, and growing vines; thick thatch roofs, double-layer roofs, and painting roofs white; electric fans, ventilation fans, skylights, etc. Enclosed pig houses can adopt a wet curtain longitudinal ventilation cooling system. Clean manure in time, maintain cleanliness and hygiene, and reduce heat produced by microbial fermentation in manure inside the house. Frequently wash the floor and walls of the pen with cool water, and install fans or air conditioners where conditions permit to lower the pig house temperature.

2. Provide enough clean drinking water

Provide enough drinking water. When pigs are in an environment more than 10°C above body temperature, water intake increases greatly. If water is lacking or the drinking water pipe is exposed to the sun, causing reduced water intake by pigs, this will aggravate heat stress in sows. Pigs can be provided with 0.5% clean water to regulate body temperature and reduce heat stress.

3. Adjust the feed reasonably

In hot weather, sow feed intake decreases. Increase the nutrient concentration of the diet, especially the content of energy, protein, and vitamins, so as to meet nutritional supply as much as possible when pig feed intake is reduced. Lysine can be added to the diet as appropriate, which can effectively reduce the adverse effects of heat stress and achieve better production results. Adding high fat to the diet can increase energy while shortening the interval from weaning to re-estrus in sows. Because fat is prone to oxidative rancidity in summer, it is recommended to add antioxidants at the same time. Except during heat stress, it is not advisable to add fat to the diet of lactating sows at other times; adding fat to the diet of lactating sows will reduce plasma insulin content and luteinizing hormone secretion.

4. Adjust feeding time

Feeding time can be changed from mainly during the day to mainly at night. Leave troughs empty during high-temperature periods, supplement feeding during cool periods, and feed less but more frequently. In addition, among the sources of body heat in livestock and poultry, heat increment accounts for a relatively large share. Leaving troughs empty and fasting during high-temperature periods is intended to reduce heat increment and avoid the superposition of heat stress.

5. Pay attention to the addition of vitamins and trace elements

Under normal conditions, the vitamin C synthesized by livestock and poultry themselves can meet their needs, and vitamin C is generally not added to feed. Under heat stress conditions, the requirement of livestock and poultry for vitamin C increases, and vitamin C can be supplemented through feed or drinking water. Vitamin E also has a certain effect against heat stress. During heat stress, some changes occur inside the body's cells. Adding vitamin E can stimulate immune organs, enhance body immunity, and help improve the ability to resist stress. Under heat stress conditions, organic trace elements can be added, thereby meeting the sow's need for trace elements to the greatest extent.

6. Add microecological preparations to the diet

In the heat stress response chain of sows, what directly causes damage to the body is free radicals. Free radicals damage body cells, disrupt maternal humoral regulation, trigger metabolic disorders, and damage the reproductive and immune systems. The main ingredients of our microecological preparations are: probiotics, antimicrobial peptides, NCG, oligosaccharides, etc.

Probiotics——improve intestinal health, reduce the production of harmful gases, and improve the breeding environment;

Antimicrobial peptides——antibacterial and antiviral, improve immunity, and enhance the sow's own stress resistance;

NCG——promote the synthesis of arginine, promote blood vessel development, and increase oxygen supply to the placenta.

Heat stress causes huge economic losses to the pig industry, and this is a practical problem commonly faced by pig producers. Through nutritional regulation, plus improvements in feeding management, and combined with the use of vitamins, trace elements, and microecological preparations, the negative effects of heat stress on sows can be effectively alleviated, and the reproductive performance and utilization rate of sows as well as the comprehensive economic benefits of breeding can be improved.

V. What injection should be given

Generally, vitamin supplements are given, because animals under stress consume large amounts of nutrients such as vitamins and amino acids to regulate balance.