Methods of relieving heat stress in pig farms

The hot environment will cause the balance disorder in the pig body. In order to maintain the stability of the internal environment, the body makes an adaptive response to the source of stress (high temperature). Excessive stress often leads to the decline of pig production performance. in severe cases, it can lead to shock or even death. The author has extensive contact with professional farmers in the process of technical guidance and follow-up service for pig raising. Now, I would like to talk about my own views on the prevention of heat stress in pigs.

1 effect of heat stress on the production of pigs

The suitable temperature for the growth of pigs is 15 ℃ ~ 25 ℃, and it is generally considered that 32 ℃ ~ 38 ℃ is the range of heat stress. When the temperature is 21 ℃, the weight gain of pigs is the best, which is lower or higher than this temperature, which has an effect on the growth of pigs. When the ambient temperature increased, the activity and feed intake of pigs decreased, drinking water increased, growth slowed down, and even reduced food.

High temperature is very disadvantageous to the growth and fattening of pigs, and the sensitivity to temperature increases with the increase of body weight. The results showed that the weight gain of pigs with body weight 45kg decreased significantly when the temperature was more than 32 ℃, and there was no significant difference in monthly weight gain of pigs with body weight 75kg in the later fattening stage under 25 ℃, but the feed intake and weight gain decreased significantly in heat stress environment above 30 ℃. The main reason for weight loss of pigs is the decrease of feed intake during heat stress.

2 measures to relieve heat stress

In pigs under heat stress, not only the physiological function of the body is disordered, the feed intake decreases, the rate of weight gain decreases, and even weight loss occurs.

2.1 create suitable environmental conditions

Doing a good job of environmental greening will help to improve the microclimatic conditions in the pig farm.

Plant vines such as grapes, towel gourd, bergamot and gourd outside the pigsty to climb the roof of the pigsty. On the one hand, green vegetation blocks the scorching sun from directly exposing the enclosure and the roof, which plays a cooling role; on the other hand, grapes and towel gourd can be killed two birds with one stone.

The outer wall of the pigsty is coated with white substance to enhance the reflection of light, reduce solar radiation heat and alleviate heat stress.

Planting fast-growing poplar around the pigsty can shade and shade the sun and shade for 2 to 3 years, reduce the heat stress of pigs, and do not affect the light of pigs after falling leaves in autumn and winter.

Install an electric fan in the pig house, carry out mechanical ventilation, force the turbid gas out of the house, speed up the convection of gas inside and outside the house, and create a cool and comfortable environment.

When there is a sudden or continuous high temperature, you can spray cold water on the floor, walls and roof of the pig house, and spray water directly on the pig body if necessary, in order to achieve the purpose of preventing heat and cooling.

2.2 feeding watermelons

When watermelons are on the market from early summer to early autumn, you can sign an agreement with watermelon growers to feed some smaller watermelons that cannot be sold at a price to pigs. These watermelons or watermelon skins are very cheap, and some of them can be obtained without even spending money, but for pigs, it is a good food for heat prevention and cooling.

2.3 adequate, cool and hygienic drinking water

Water plays an important role in the regulation of body temperature, so under the condition of heat stress, clean, adequate and hygienic cold water must be provided, of which deep well water is the best, and pay attention to frequent replacement.

2.4 reasonable arrangement of feeding time

Due to the relatively low temperature in the morning and evening, the appetite of pigs is relatively strong, and feed intake can be increased at this time.

2.5 do not raise too much density.

The increase of house temperature caused by high feeding density should be avoided in summer. Generally speaking, for pigs below 60kg, each covers an area of not less than 0.7m2; for pigs above 60kg, it is better to have no less than 1m2 per pig.

2.6 increase the energy level in the diet

In order to alleviate the decline of production performance of pigs affected by high temperature environment, diets with higher nutrition should be given in high temperature season to make up for the problem of insufficient energy intake caused by high temperature. Because the digestibility of feed fat of pigs during heat stress is higher than that of other nutrients, adding 2% to 3% fat in pig diets can, on the one hand, increase the energy level of the diet and stabilize the weight gain rate of pigs. on the other hand, it can also improve the palatability of feed, increase feed intake and ensure energy intake, thus promoting growth.

2.7 supplementation of restricted amino acids in the diet

During heat stress, it is necessary to adjust the content of dietary crude protein, and feeding synthetic lysine instead of natural protein is beneficial to pigs. Supplementing 0.3% lysine in the diet can reduce heat consumption in the diet and significantly improve feed conversion rate and pig production performance.

2.8 Sodium bicarbonate is added to the diet

Sodium bicarbonate has a wide range of sources and is cheap. It can dissolve mucus, strengthen stomach, inhibit acid and increase appetite. Absorption into the body can supplement the sodium needed by the body, and act as the main buffer substance in blood and tissue, slow down respiratory alkalosis and improve the ability of resistance to heat stress. Adding 0.5% sodium bicarbonate to the feed is the best way to overcome the disturbance of acid-base balance and hindered production performance caused by heat stress.

2.9 Vitamin C supplementation and vitamin supplementation

In the process of heat stress, vitamin C helps to maintain a high feed intake, so as to ensure adequate nutrition supply and resist the adverse effects of heat stress. At the same time, vitamin C can synthesize the steroid hormone corticosterone, enhance the immune function of the body, and reduce the mortality of pigs under high temperature. Adding 400mg/kg vitamin C to the diet of pigs can improve the immunity of the body, effectively relieve heat stress and improve production performance.

Vitamins also play a role in anti-heat stress, and some changes have taken place in the cells of the body during heat stress, so the addition of vitamin E can stimulate immune organs, enhance immunity and improve the ability of anti-stress. The addition of vitamin E 200IU / kg can effectively relieve heat stress and improve production performance in pigs.

2.10 use of anti-stress drug additives

The body temperature of pigs increases during heat stress. In order to reduce unnecessary muscle activity and heat production, sedatives can be used to inhibit central nervous system and body activity to reduce the effect of heat stress. Chlorpromazine or diazepam can be added to feed. In addition, bacitracin zinc 100mg/kg or flavomycin 2.5mg / kg + oxytetracycline 50mg/kg can be used to enhance the disease resistance of livestock, inhibit the reproduction of harmful bacteria in the intestinal tract, promote growth, improve feed utilization, and relieve heat stress to a certain extent.

2.11 use of Chinese herbal medicine additives

Chinese herbal medicine is rich in vitamins, trace elements and other active ingredients, which can enhance the immunity of the body, comprehensively coordinate physiological metabolism, thus play the role of relieving heat stress and anti-heat stress. Chinese herbal medicine feed additive has the functions of appetizer, heat-clearing and detoxification, heat-relieving and heat-relieving. Commonly used Chinese herbal medicines are: Bupleurum, Reed root, licorice, dandelion, wild chrysanthemum, Scutellaria baicalensis, patchouli, honeysuckle, Radix Isatidis, Atractylodes, Gentiana, Acanthopanax senticosus and so on.