Management Of Birds During Summer Seasion
Chickens are very sensitive to environmental temperature.
Their growth, egg production and health are severely affected during extremes of weather.
Therefore, within the economically feasible limits, ideal temperature has to be provided to the birds, in order to obtain optimal growth rate and returns from the birds.
For optimum feed efficiency, an ideal temperature range of 21oC- 24oC is needed. However in tropical climates, these temperature ranges may be obtained during winter only.
The various physiological and pathological changes that take place in the flock, during high summer temperature are as follows:
Energy intake and thereby feed consumption and other nutrients intake reduce as the environmental temperature increases. This is because birds need less energy for maintenance of body temperature, when the ambient temperature is high. Consequently, growth rate and body weight of birds will become lower.
There will be early two-fold increase in the water consumption of birds during summer; because during high environmental temperature the major way to lose the excess heat produced in the body is by loss of water vapour through expired air.
High ambient temperature increases the respiratory rate and body temperature. Since there are no sweat glands in Poultry, they will start panting vigorously, in order to lose the excess body heat produced. As the outside temperature increases the heat production as well as the heat loss from the body decreases.
High environmental temperature on the other hand decreases oxygen consumption, blood pressure, pulse rate, thyroid size and activity, blood calcium level and body weight.
The problems with ectoparasites will be more during summer and the following monsoon. Moreover, high environmental temperature associated with high relative humidity (>70%) may lead to outbreaks of Coccidiosis.
Incidences of Fatty Liver Haemorrhagic Syndrome and other metabolic disorders like heat stroke, liver rupture etc. are more during summer; especially in case of heavy broilers.
Birds will shed more feathers during summer, in order to lose the excess body heat produced.
At high environmental temperatures, nearing the body temperature of the birds, vapourisation of body water through respired air is the only way to lose substantial amount of heat from the body.
Caged birds and birds reared on slatted floors will suffer more due to high environmental temperature than birds reared on litter floors; because birds on litter can cool themselves to some extent by dusting themselves in the litter.
Heavy mortality due to heat stroke will be noticed among heavy broilers, in the late afternoon and evening.
Temperature affects egg breakage. Elevated environmental temperature is associated with decrease in shell quality.
Reduction of shell thickness produced by heat stress is apparently due to respiratory alkalosis which causes lowering of partial pressure of carbon dioxide in the lungs and raises blood pH.
As the ambient temperature increases above 26oC, the egg size declines.
Measures to overcome
The above adverse effects due to high environmental temperature can be overcome to a considerable extent by proper management of the flock, house, feed etc. during summer, as indicated below:
By proper roofing, the temperature inside the poultry houses can be kept at 5o - 10oC below the outside temperature. Thatched roofing of about six inches thickness provides optimum comfort to the birds during summer, than any other roofing material.
In large farms, aluminium roof is preferred due to its durability, resale value and rear reflecting properties.
In case of non-insulated houses, the roof must be raised to a sufficient height from the floor level;
The eaves at the roof shall project out atleast one metre on all the four sides as over hang to prevent direct sun light and rain water entering into the house.
Provide "ridge-ventilation" such as "half-monitor" or "full monitor".
In tropics, in order to prevent direct sun light falling into poultry houses, the long axis of the houses have to face north and south i.e. the houses must be orientated east to west; with a slight tilt towards southern side in the east and towards north in the west.
Open type, cross-ventilation is recommended in tropics. Except for a 20cm height wall, all the four sides upto the roof should be provided with 12mm size and 18 gauge chicken wire mesh or 25mm size chain link mesh.
As far as possible the width of poultry houses shall not exceed 10 metres. If the width of the poultry house exceeds 10 metres, cross-ventilation alone may not be effective in providing proper air flow in poultry houses
Provide tunnel ventilation along with pad coolers and/or foggers, to produce evaporative cooling. During hot summer, this mechanical ventilation, with evaporative coolers should be functioning from 10 A.M. to 6 P.M.
Sprinklers may be fixed on the top of the roof and operated continuously from 10 to 18 hours, to cool the roof.
Foggers may be fixed inside the broiler house and operated during hot and dry weather, to produce evaporative coolness.
Grow "fast-growing" shady trees around poultry houses in order to reduce the severity of the summer heat waves and also to break wind drafts during monsoon.
Rear relatively more heat tolerant strains of broilers suitable for tropical climate.
During hot weather, birds consume twice the amount of water than that is normally consumed.
In order to encourage the feed intake of birds during summer, reduce the energy content of the feed by about 10 percent.
Since feed consumption generate more body heat, avoid feeding broilers over four weeks of age, during hot weather. If automatic winchable feeders are used, lift the feeders between 9 and 18 hours.
Nearly 10 to 15% of the calories (energy) in the feed, of carbohydrate and protein origin, may be replaced by fat /oil energy, by adding 2 to 3% oil or fat.
Large farms in hot and dry climate may opt for environmentally controlled poultry houses.
Drugs and chemicals like electrolytes, ascorbic acid, sodium bicarbonate, tranquilisers, sodium salicylate, paracetamol, chlorpromazine hydrochloride, cyproheptadine hydrochloride may be administered through feed or water, to make the birds to withstand hot weather.
Thick and wet litter produce/ generates more heat. Therefore, during summer, the litter thickness must not be more than 6cm.
Avoid over crowding. Increase floor space by atleast 10% during summer.
If mechanical ventilation is provided, increase the air flow rate and air exchanges by atleast 25%, during summer.
Do not disturb the birds and make them panic during hot weather.
For birds kept in cages, the centre height of building should be a minimum of 14 feet.
Addition of 0.48 percent potassium chloride to water lowered heat stress in layers.
Add 1kg of sodium bicarbonate to one tonne of feed to lower heat stroke and to increase shell thickness.
Two kg of sodium bicarbonate may be added to one tonne of feed.