The suitable temperature for egg production is 13-20 degrees, of which the highest egg production rate is 13-16 degrees, and the feed reward is 15.5-20 degrees. When the temperature exceeds 30 degrees, it will cause a series of adverse physiological and mental reactions of the chicken. In hot summer, high temperature has a great influence on the growth of laying hens, egg production, egg weight, egg shell quality, fertilization rate of egg, and feed remuneration.
1. Physiological changes in laying hens under high temperature stress Under high temperature stress, the hypothalamus synthesizes and releases corticotropin-releasing hormone, reaching the anterior pituitary through the pituitary portal system. The pituitary gland secretes adrenocorticotropic hormone, which reaches the adrenal gland through blood circulation and promotes the synthesis of corticosterone by the adrenal gland, resulting in high nervousness of the chicken, rapid heartbeat, reduced feed intake, and reduced sexual activity; the body begins to use a large amount of internal energy to make blood glucose Increased body protein breakdown, chicken growth is slow, gradually weight loss, osteoporosis, egg weight reduction, eggshell quality, increased breakage, protein thin. Under stress conditions, the bursa of Fabricius, spleen, and thymus atrophy, and the lymphatic system declines, resulting in a reduction of peripheral lymphocytes and eosinophils, and reducing the body's resistance to disease. The amount of vitamin synthesis in the body decreases, but the requirement increases, causing the chicken body. lack of. Therefore, stress has an adverse effect on the growth, health, and production of laying hens.
2, the impact of high temperature environment on laying hens
2.1 Affecting Feed Consumption In actual production, the ambient temperature at 25-340C decreases 1~1.5g/d for every 1~C feed intake, and the loC increases the feed intake for 4.2g/d at every 32–36oC.
2.2 Affecting Egg Production When high temperature attacks, the survival requires heat dissipation, which causes a series of reactions - heart rate and breathing speed. These physiological reactions require energy. Energy can only come from protein, carbohydrate and fat breakdown. Energy can not be used for egg production when it is used for stress, so the common egg production declines under high temperature stress conditions.
2.3 The temperature of the digestive environment affecting nutrients affects the digestive tract motility and the secretion of digestive enzymes in laying hens, thereby altering the evacuation rate of chyme and affecting the digestion of feed. Under high temperature stress, the activity of intestinal protease and amylase decreased, which may be mainly due to the decrease of enzyme secretion.
2.4 Influencing the Metabolism Utilization of Nutrients When animals are in the heat stress zone, the animal does not need to produce heat to maintain body temperature and the total body metabolism is lower due to the inhibition of feed intake and production. However, animals need to enhance metabolic reactions during the process of dissipating residual heat in the body. Therefore, the metabolic intensity of nutrients in the body is higher than that in the moderate temperature zone. That is, as the temperature of the environment increases, the metabolic energy value of the feed decreases.
3, the measures taken
3.1 heatstroke cooling
3.1.1 Strengthen ventilation and ventilation in the house, install exhaust fans and ceiling fans, increase air flow speed, and ensure indoor air is fresh.
3.1.2 Plant shade-absorbing plants around the house to absorb heat, or install parasols at the windows to avoid direct sunlight and prevent the occurrence of licking.
3.1.3 Spray water directly to the roof of the chicken house, take away the heat by the regulation of water and evaporation of water. Or direct spray to the chicken body, 1-2 times a day (about 2:00 pm, 7:00 pm), this method can reduce the indoor temperature 5-70C, but to ensure good ventilation and avoid excessive humidity. Artificial rain equipment can also be installed on conditional conditions.
3.2 Increase the temperature of drinking water in chickens, increase the amount of chicken body water dispersal, and its water demand also increased accordingly, while increasing the water for chickens, when the house temperature is higher than 32 ~ 350C, in its drinking water Add appropriate amount of vitamin C, electrolyte, etc. to achieve the purpose of cooling and preventing heat stroke.
3.3 Adjust the nutritional structure of the diet
3.3.1 Regulation of energy, protein and amino acids. As the temperature of the chicken increases, the amount of water consumed by the chicken increases and the feed intake decreases. This affects the nutritional needs of the chicken itself and its normal production performance (eg, growth, egg production, etc.). Therefore, it is beneficial to properly adjust the nutritional level of feeds, properly increase energy and protein content, and increase the protein/energy ratio of the diet. According to some scholars' studies, it is shown that adding proper amount of animal fat (1.5%) to layer diets in summer can enhance the palatability of feed, and has a good effect on improving egg production rate, feed conversion efficiency, and economic efficiency.
3.3.2 Vitamin C in diets Chickens need only a large amount of vitamin C in heat stress to meet the body's consumption of body heat. In addition, vitamin C can inhibit the increase of body temperature, increase feed intake, and enhance the body Disease resistance, dosage 100~300g/t.
3.3.3 Add electrolytes to the diet. Adding potassium chloride, ammonium chloride, and sodium bicarbonate to the diet can increase egg production and improve eggshell quality.
3.4 Add drugs to relieve heat stress
3.4.1 Recent studies have suggested that citric acid is a promising stress-protective agent in the poultry industry and can alleviate heat stress.
3.4.2 Add bacitracin zinc, can reduce heat stress, improve feed conversion rate, the amount of 10-30g/t.
3.5 Strengthening feeding and management work
3.5.1 Improve feeding methods, mainly in the morning and evening, increase the number of feedings and feeding amount.
3.5.2 In the summer, in particular, it is necessary to do a good job of cleaning, adhere to daily cleaning of drinking water equipment; regularly disinfect; timely clean chicken manure, eliminate mosquitoes and flies.
3.5.3 The breeder shall inspect continuously and continuously and find that the chickens with heat-stroke symptoms are promptly transferred to a cool place.
3.5.4 It may be appropriate to add green and juicy green feed such as cabbage leaves and watermelon rinds.
3.5.5 Control unnecessary personnel and vehicles to prevent the transmission of pathogens.
3.6 Enhancing awareness of fowl disease prevention As a result of the high ambient temperature and other unfavorable factors, the immune function of chickens will decline, which may lead to an increase in the incidence of chickens, especially E. coli, staphylococcal disease and atypical Newcastle disease. Wait. Therefore, especially for chickens raised on the ground while strengthening the cooling and heatstroke prevention measures, efforts should be made to strengthen epidemic prevention.
3.7 Doing well in daily management of flock management In the production process, the production record is a basic content that reflects whether the flock production is normal. Through the recorded content, various indicators of chicken performance can be analyzed, such as daily intake, egg production, etc., to analyze whether the chicken is normal, observe the feces to analyze the occurrence of the disease. In short, in the hot summer months, comprehensive measures should be taken to create a suitable environment for the flock to ensure a healthy and productive flock.
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