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May 31, 2015
Due to the common occurrence of environmental stressors worldwide, many studies have investigated the detrimental effects of heat stress on poultry production. It has been seen that heat stress negatively affects the welfare and productivity of broilers and laying hens. Understanding and controlling heat stress in poultry is crucial to successful poultry production and profitability. Heat stress is one of the most critical environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth to decreased egg production, egg quality, and safety. Moreover, the negative impact of heat stress on poultry welfare has recently attracted increasing public awareness and concern.
The environment in which poultry is maintained is the most critical factor affecting productivity. The thermoregulatory mechanism in birds is effective only upon the ambient temperature within certain limits (180-280 c); beyond this, a bird cannot adjust well. The lethal upper temperature in birds is about 470 c. Birds do not change their behaviour or signs of discomfort and use the minimum amount of metabolic energy to maintain a homoeothermic range of body temperature. Within the thermoneutral zone, body temperature is supported by the thermal equation (heat production=heat loss).
Birds become heat stressed when they have difficulty achieving a balance between body heat loss and body heat production, the average body temperature of poultry is 410 c. When the environmental temperature exceeds 350 c , a bird is likely to experience heat stress. In effect, to maintain body temperature, birds first rely on losing heat from blood vessels near the surface of the skin by a process called non-evaporative cooling. However, this mechanism is only effective when the ambient temperature is lower than the bird’s body temperature. As ambient temperature increases beyond the bird’s thermoneutral zone, non-evaporative cooling becomes ineffective. At these higher temperatures, the bird relies on panting/evaporative cooling to control body temperature. Panting is an effective but energy-expensive way for the bird to regulate body temperature. It typically results in lower feed intake and growth and reduced feed efficiency.
It will also increase water intake to offset water loss. Still, the situation is complicated because the body’s ability to retain water is reduced as the evaporative cooling process escalates. During high ambient temperatures, the birds increase panting up to 10 times from an average rate of 25 breaths/min to 250 breaths/min, which leads to an excessive loss of carbon dioxide resulting in raised blood plasma bicarbonate levels and increased blood ph. The bird attempts to correct blood ph. by excreting bicarbonates via urine. Bicarbonates are negatively charged ions coupled with positively charged ions such as potassium to be passed in the urine. However, as potassium is essential in maintaining intracellular water balance, a loss of potassium ions via urine reduces the ability to maintain this water balance. Consequently, while birds compensate for water losses associated with panting by consuming more water, their retention in the body cells is limited by simultaneous loss of electrolytes such as potassium in the urine.
The most important effect of heat stress is to decrease body resistance and more susceptibility to E.Coli and CRD. In the condition of CRD & E-Coli, Respiratory Herbs should be given; it is a very effective herbal medicine for CRD & E-Coli.
Also, outbreaks of Gout may be seen in broilers and layers. In heat-stressed birds, blood flow increases to the upper respiratory tract, skin, and abdominal muscles for relieving heat. However, blood flow to the intestinal tract is decreased; thus, there is a reduction in appetite leading to lower feed intake. Concurrently water intake is increased, resulting in fluid contents in the intestinal tract. This further causes diarrhoea that results in loss of electrolytes needed to maintain acid-base balance. In this condition, Electral Energy is very much effective.
The following clinical signs will be observed in heat-stressed birds :
The aim of adopting measures to combat heat stress is to keep birds alive and get production out of them to achieve targeted figures, i.e., the egg from layers and better body weight at particular age with specific FCR in broilers.
The following steps will help to combat heat stress in poultry farming in summer :
Practically water is the essential criterion of these four managemental factors during summer. In summer, water consumption is 3-4 times more. Even a slight shortfall of water can lead to heatstroke and mortality. Usually feed, and water consumption ratio is 1:2, but when the temperature shoots beyond 950F, this ratio may increase to 1:4 or more. The following points are to be taken into consideration for the poultry water in summer :
With some attention to proper management to combat heat stress, the poultry flock will remain healthy and productive throughout the summer. These simple methods will help you to maintain the bird’s health & productivity in hot weather. These guidelines will directly or indirectly make unexpected results in total poultry production.
I wish you all the best while doing poultry farming in the summer!
It would help if you also read Heat Stress in Layer Poultry.