Effect of induced stress and antistress agents on the physiological parameters in broiler chicken
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Date
2003
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Department of Physiology, College of Veterinary and Animal Sciences, Mannuthy
Abstract
In modern poultry production system various factors namely floor space
reduction, feed and water restriction, high environmental temperature,
vaccination, medication, debeaking etc. have the potential to induce stress in
poultry which results in poor performance as well as reduction in immune
response as the nutrients normally utilized for growth and production are
diverted to counteract the stress and survival. The study was undertaken with the
objective of evaluating the influence of induced stress and anti stress agents
(dietary ascorbic acid and Zeetress®) on various physiological, biochemical and
production parameters in broiler chicken. Fifty six numbers of day old broiler
chicks (Vencob) procured from a commercial hatchery were reared in battery
cages under the standard managemental conditions upto four weeks of age. Then
they were randomly selected and divided into seven groups (G-I to G- VII) with
eight birds per group. The birds in different groups were as follows: G-I as the
control, G-II as floor space reduced group (33%), G-III as floor space reduced
group supplemented with Zeetress® @ 0.01%, G-IV as floor space reduced
group supplemented with ascorbic acid @ 0.02%, G- V as 30% feed restriction,
G- VI as 30% feed restriction with dietary supplementation of Zeetress® @
0.0 I % and G- VII as 30% feed restriction with dietary supplementation of
ascorbic acid @ 0.02%. The birds were maintained in battery cages under
standard managemental conditions on broiler ration with the exception of floor
space reduction, feed restriction and incorporation of dietary anti stress agents.
Production parameters such as weekly weight gain and feed efficiency were
analyzed on weekly basis. Blood was collected with suitable anticoagulants,
initially at fourth and then at sixth and eighth week of age. Whole blood was
utilized for analysis of haematological parameters, heterophil: lyrnphocyte (H:L)
ratio and mitogen induced lymphocyte proliferation test. Plasma was utilized for
biochemical analyses i.e. for protein profile, lipid profile and estimation of
glucose, uric acid and cortisol. The data were statistically analysed by
appropriate tests.
The birds of G- V group showed significantly lower values of TEC, Hb,
VPRC and TLC at sixth and eight week of age. The dietary supplementation of
Zeetress® and ascorbic acid in floor space reduced groups feed restricted
groups did not show any significant influence on the values of TEC, Hb,
VPRC, ESR, TLC when compared to the birds of respective stress induced
groups G-II and G- V.
The birds of stress induced groups G-II and G- V had lower lymphocyte
count and higher heterophil and basophil count, higher H:L ratio and
suppressed mitogen induced lyrnphocyte proliferation (probably due to a rise in
level of plasma corticosteroids as a result of stress response) when compared to
birds of G-J group, both at sixth and eighth week of age.
Dietary
supplementation of Zeetress® and ascorbic acid in floor space reduced groups
and feed restricted groups elevated the lymphocyte counts, suppressed
heterophil and" basophil counts, H:L ratio and considerably improved the
mitogen induced lymphoblastogenic response both at sixth and eighth week of
age.
In the present study the birds of G-II and G- V group had no significant
variation in plasma protein profile and glucose levels but had increased plasma
concentration of ortisol (probably due to stress induced adrenal hyper activity)
and decreased uric acid, when compared to birds of control group G-I, both at
sixth and eighth week of age. Dietary Zeetress® and ascorbic acid
supplementation in floor space reduced groups and feed restricted groups
showed a lower plasma concentration of cortisol both at sixth and eighth week
of age, and significantly increased uric acid at eighth week of age.
Dietary supplementation of Zeetress® and ascorbic acid in floor space
reduced groups decreased plasma concentration of cholesterol both at sixth and
eighth week of age and total lipids at sixth week of age. In birds of feed
restricted G- V group plasma concentration of cholesterol, triglycerides and total
lipids were lower both at sixth and eighth week of age when compared to birds
of control group G-I. The dietary supplementation of Zeetress® and ascorbic
acid in feed restricted groups had no significant influence on plasma
concentration of cholesterol both at sixth and eighth week of age. However,
there was an increased concentration of triglycerides both at sixth and eighth
week of age with significant increase in total lipids at eighth week of age, when
compared to birds of G- V group.
There was no significant variation In body weight and weight gain of
birds in all floor space reduced groups compared to birds of control group (G-I)
at all weeks of age with the exception of lower weight gain in G-IJI and G-IV
when compared to G-II at eighth week of age. The body weight and weight
gain in the birds of all feed restricted groups were lower when compared to
birds of control group (0-1), at all weeks of age.
A perusal of the overall feed efficiency from 5 to 8 weeks of age
revealed that the birds of 0- VI group supplemented with Zeetress® recorded a
superior FE (2.22) whereas an inferior value of 2.59 was noted in 0- V group
without any dietary antistress agent. The control group recorded a FE of 2.29.
Zeetress® supplementation improved overall FE in feed restricted group (0-
VI). On the other hand this advantage was not observed in floor space reduced
group (O-IlI). Dietary ascorbic acid improved overall FE only in case of feed
restricted group 0- VII when compared to that of 0- V group. However, in floor
space reduced group (O-IV), ascorbic acid supplementation could not improve
the FE.
The observations of the present study revealed that both feed restriction
and floor space reduction resulted in some sort of chronic stress which led to
variation in haematological and biochemical parameters, and impaired growth
(in feed restricted groups). Analysis of TLC, OLC, mitogen induced
Iymphocyte blastogenic response and plasma cortisol values indicated that there
was a marked level of immunosuppression in the stressed birds. The magnitude
of variation in most of these parameters was higher at sixth week of age when
compared to that of eighth week values indicating some sort of habituation/
adaptation occurred upon chronic stress in the broiler chicken. The antistress
agents - Zeetress® and ascorbic acid were equally effective in reversal of stress
induced alterations in haematological, biochemical and production parameters.
Description
MVSc
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Citation
172043