482
A. Soliman and A. M. Safwat
environmental temperature due to climate change on poultry production representing
lower feed intake, reduction of weight gain and meat quality in broilers, in addition
to low egg production rate and egg quality, increasing feed conversion ratio and high
mortality rate in laying hens.
An increase in global average surface temperature by 2100, between 0.3 and
4.8 °C, is reported in the IPCC Fifth Assessment Report [1]. That could have several
impacts on livestock production including variation in production and quality of feed
crops and forage, and biodiversity, water availability and animal health, growth, production and reproduction. Therefore, effective procedures must be taken to challenge
this potential risk of high temperature and its impact on livestock in general and on
poultry in particular through the implementation of effective strategies in order to
protect poultry survival and increase their productivity during hot weather.
2 Response of Heat Stress in Poultry Herds
2.1 Maintenance of Body Temperature
Chicken is a homeothermic animal, which has the ability to maintain a relatively
constant temperature of its internal organs. But this ability is highly efficient only
when the thermoneutral zone about 21–28 °C which called the temperature range or
comfortable zone, through balancing between the body amounts of heat produced
and the amount of heat lose. The large part of the heat produced through the body
metabolism, which increases the need to increase the elimination of heat to maintain
the body temperature at the normal limit of 41.4–42.9 °C. Therefore, the high temperature of the surrounding environment to the direction of a large part of the production
capacity in order to maintain the body temperature at the natural limits through a
series of physiological changes that work on the stability of body temperature. These
changes have direct and indirect negative effects in efficient bird production.
The loss of heat in poultry when exposed to high environment temperature is not
through sweating due to lack of sweat glands in the body of poultry and the process of
controlling the mechanism of regulating the temperature of the birds by hypothalamus
in two ways: The first is sensible heat loss through conduction, convection, fecal
excretion, egg production. This system works efficiently in the thermal range, here
the size of the comb and wattles plays an important role by providing the body with
sufficient space bare skin which provides blood, which transfers the heat from the
body to the head to be lost in concrete form, we found that the bird loses about 40%
of the heat who wants to get rid by this way. The second is an insensible heat loss,
which includes exhaustion and increased evaporative cooling due to increased heart
rate, blood flow to the skin and expansion of peripheral blood vessels. Evaporation
occurs mainly in the lungs, air sacs, and mucous area between the nasal openings
and the tracheal base.
A. Soliman and A. M. Safwat
environmental temperature due to climate change on poultry production representing
lower feed intake, reduction of weight gain and meat quality in broilers, in addition
to low egg production rate and egg quality, increasing feed conversion ratio and high
mortality rate in laying hens.
An increase in global average surface temperature by 2100, between 0.3 and
4.8 °C, is reported in the IPCC Fifth Assessment Report [1]. That could have several
impacts on livestock production including variation in production and quality of feed
crops and forage, and biodiversity, water availability and animal health, growth, production and reproduction. Therefore, effective procedures must be taken to challenge
this potential risk of high temperature and its impact on livestock in general and on
poultry in particular through the implementation of effective strategies in order to
protect poultry survival and increase their productivity during hot weather.
2 Response of Heat Stress in Poultry Herds
2.1 Maintenance of Body Temperature
Chicken is a homeothermic animal, which has the ability to maintain a relatively
constant temperature of its internal organs. But this ability is highly efficient only
when the thermoneutral zone about 21–28 °C which called the temperature range or
comfortable zone, through balancing between the body amounts of heat produced
and the amount of heat lose. The large part of the heat produced through the body
metabolism, which increases the need to increase the elimination of heat to maintain
the body temperature at the normal limit of 41.4–42.9 °C. Therefore, the high temperature of the surrounding environment to the direction of a large part of the production
capacity in order to maintain the body temperature at the natural limits through a
series of physiological changes that work on the stability of body temperature. These
changes have direct and indirect negative effects in efficient bird production.
The loss of heat in poultry when exposed to high environment temperature is not
through sweating due to lack of sweat glands in the body of poultry and the process of
controlling the mechanism of regulating the temperature of the birds by hypothalamus
in two ways: The first is sensible heat loss through conduction, convection, fecal
excretion, egg production. This system works efficiently in the thermal range, here
the size of the comb and wattles plays an important role by providing the body with
sufficient space bare skin which provides blood, which transfers the heat from the
body to the head to be lost in concrete form, we found that the bird loses about 40%
of the heat who wants to get rid by this way. The second is an insensible heat loss,
which includes exhaustion and increased evaporative cooling due to increased heart
rate, blood flow to the skin and expansion of peripheral blood vessels. Evaporation
occurs mainly in the lungs, air sacs, and mucous area between the nasal openings
and the tracheal base.