The suitable temperature for egg production is 13-20 degrees Celsius, of which the highest egg production rate is 13-16 degrees Celsius, and the feed reward is also the best. When the temperature exceeds 30 degrees Celsius, 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 hypothermic 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 Effect of high temperature on laying hens
2.1 Affecting Feed Intake In actual production, ambient temperature at 25-340C reduces feed intake by 1-1.5 g/d for every 1C increase, and loC by 32-36°C reduces feed intake by 4.2 g/d.
2.2 Affecting egg production When the high temperature attacks, the survival requires heat dissipation, which leads to 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 peristalsis of digestive tract 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 a heat stress zone, the animals do 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 measures taken
3.1 Summer cooling
3.1.1 Strengthen ventilation and ventilation in the house, install exhaust fans and ceiling fans, increase air flow rate, and ensure indoor air is fresh.
3.1.2 Plant shaded plants around the house to absorb heat, or install parasols at the windows to avoid direct sunlight and prevent the occurrence of licking.
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