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Bas.J.Vet.Res.Vol.19, No.2, 2020.
THE IMPACT THERMAL STRESS ON SOME
PHYSIOLOGICAL, ENDOCRINE PROFILES AND HSP IN
LOCAL MALE CALVES
Jinan A. Hilal, Muna H. AL-Saeed
Department of Physiology, Pharmacology and Chemistry, College of Veterinary
Medicine, University of Basrah,Basrah, Iraq.
(Received 22 June 2020 ,Accepted 5 May 2020)
Keywords: Thermal Stress, Endocrine Profile, Male Calves.
ABSTRACT
This study was conducted in the field cattle in Al-Qurna, north of Basra
Governorate, in the period between July 2018 to February 2019 and included the
following seasons, the monthly summer season(July and August of 2018), the
monthly autumn season (October and November of 2018) and the winter season is
monthly (January and February of 2019) .This experiment was designed to reveal the
effect of the THI value on some physiological and hormonal values on the local male
Holstein. The studied group include 20 calves and with age between (one year to one
year and eight months), twenty blood samples were collected per month from male
Holstein calves subjected to a different value of temperature and humidity in different
months and seasons.The results of the first experiment showed: A significant(P≤0.05)
increase in the values of THI, respiratory rate, and heart rate, where a
significant(P≤0.05) increase was noted in months and the summer season except for
the rectal temperature, which showed no significant difference (P˃0.05) among
different seasons. The antioxidants CAT, MDA, SOD, and GPX also showed a
significant increase (P≤0.05) during the summer months and seasons compared to the
autumn and winter months and seasons. Also significant increase (P≤0.05) in cortisol
and HSP70 during the summer and season months.The levels of testosterone and
thyroid hormone (T4) and triiodothyronine (T3) decreased significantly (P≤0.05)
during summer and season compared to other months and seasons, but the level of
insulin in the blood showed a significant decrease (P≤0.05) during the summer season
than the other seasons.
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INTRODUCTION
Large domestic animals are exposed to various kinds of stress such as physical,
nutritional, chemical, psychological and thermal stress. Changes in natural
environmental factors are seen as main affecting in live stock animal's health and
production(1). Which lead to huge economic losses is about 60% of the dairy farms
production around the world (2). Elevated the global warming, air humidity and
sunlight based radiation are condition focusing on factors that potential hazard on the
animal's biological systems (3).
On the among the normal variables impacting trained the domesticated
animals, ecological temperature is one of the most interesting components has an
unfavorable effect on cattle's health (4). Augmentation in air temperature during
summer season is one of the standards of the natural change which is risking the
conceptive capacities, production and wellbeing of the domesticated animals through
all the world, specifically in tropical and subtropical countries (5). Along these lines,
the normal occasional changes are perceived as a physiological stressors which
impact in the creature's natural frameworks (behavioral, biochemical, immunological
and physiological changes)(6).
Hence, the importance of these climatic changes becomes clear if we know
that by the end of the 21th century it is expected that the numbers of hot and dry
summer days will increase and the temperature and climate changes will affect the
tropical and sub-tropical regions more like the geographic region in which Iraq is
located(7). The temperature degree increases and the number of dry days, as well as
the decrease in the intensity of rain (8). Over hundreds of years, natural selection
acted on local breeds, resulting in animals obtained unique adaptive traits such as
disease resistance and tolerance to heat and cold(9).
The importance of selecting the most resilient and adaptive animals to
climatic changes and different stress conditions arises through the selection of some
molecular mechanisms in protecting the cells that protect them from the effects of
heat stress and different stress conditions(10), and the most important of these
molecular mechanisms that body possesses are a family of heat shock proteins(HSP),
especially heat shock proteins 70 (HSP70),which activation when animals exposure to
heat or cold stress that have the ability to protect and keep the cells alive when
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exposed to different stress conditions, by act as molecular chaperones in regulating
the cellular homeostasis and folding and unfolding of damaged proteins during the
stress(11). This study aimed to evaluate the effect of natural change in temperature
humidity index (THI) value at different months and seasons on most physiological
parameters and ability Holstein calves for adaptive to this conditions and also evaluate
the level of serum heat shock protein 70 (HS70) adaptive Holstein calves.
MATERIALS AND METHODS
A total twenty male calves (1-1.8) years old was used in this study which
exposed to different value of temperature humidity index ( THI ) during different
months and season of years from cattle filed of the private sector in the area of Al-
Quranh, north of Basrah Governorate, Iraq and all tests has been done in the
laboratories of the college of Veterinary Medicine at the University of Basrah,
including the physiological laboratory, medicinal laboratory, central research unit and
Bayan Group For Advance Laboratories Diagnostic. The animals were supplied with
a standardized food as well as green fodder free once a week. Salts and drinking
water were constantly present in front of the animals. According to Minimum and
maximum temperatures and humidity percentage values were obtained from the
reports of Basrah Metrological service in Basrah, Governorate, the temperature
humidity index (THI) value was calculated by (12).
The pulse rate, respiratory rate and rectal temperature was measured once time
monthly according to (13), About 20ml of blood samples were collected from Jagular
vein calves in the morning at (8-10)by using disposable syringe (20ml). Some of
blood samples were collected in gel tube for serum samples for biochemical analysis
were separated by centrifuge at (3000 rpm for 15 minutes) to obtained the serum, and
these samples separated in many eppendorf tubes to avoid repeated thawing and
stored at (-4ºC) until they were analyzed.
Biochemical parameters : the determination of superoxide dismutase (SOD)
activities, is based on SOD ability to inhibit of pyrogallol autoxidation.
By(14), The colorimetric method by (15) used to detect the serum value of MDA,
√while the effectiveness of serum catalase enzyme was measured by modified
manner by (16), and the sandwich-ELISA kit was used to detect the GPx activities
by (17).
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Bovine heat shock protein70 serum levels was detected by using enzyme linked
immunosorbent assay (ELISA) kit manufactured by Shanghai Korain Biotech
Company,China. Hormonal Profile: The thyroxin (T4), total triiodothyronine hormone
(T3), cortisol, testosterone, and insulin hormones were estimated in Bayan Group For
Advance Laboratories Diagnostic .
Statistical Analysis
Data was analyzed by using SPSS (Statistical Program for Social Sciences)
program version 22.0 and presented as mean ±standard deviation(18). One way
ANOVA was used to compare mean different among more variable.
RESULTS
1-The Maximum, Minimum Temperature, Relative Humidity and Average THI
Value During Months and Seasons of Study Period
The maximum and minimum climate temperature and relative humidity
percentage are obtained from the Basrah Meteorological Center is clarified in the
Table (1), and revealed that high value of maximum and minimum climate
temperature was obtained during July and August months(47.63±1.44, 47.46±1.43
and 28.40±1.13 , 27.16±1.01), while the lowest values were recorded during January
month (19.90±1.39, 6.90±2.13) respectively than others months.The high and low
value of maximum of relative humidity percentage was recorded during January and
July (72.09±5.17, 26.03±3.14) respectively, but a highest and lowest value of
minimum relative humidity percentage was recorded during February and July
months (26.71±1.86, 7.26±2.25) respectively than the others months.
The mean ±SD value of monthly average of temperature and relative humidity
percentage during different months were reveled in the Table (2). In the present study,
a highest and lowest values of average climate temperature was obtained from July
and January months (38.166±0.79 and 12.82±0.92) respectively, while a highest and
lowest values of the relative humidity percentage was obtaind during February and
July months (48.96±1.77 and 16.90±2.13) respectively.
The average value of temperature humidity index(THI) during different months
and seasons of experimental study period are present in Table (3). The average THI
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value varied among different months and seasons. The average THI value was
recorded high significant (p≤0.05) with summer season, where recorded highest value
(85.22±0.41) in August months compared to the rest months, while the lowest
significant (P≤0.05) was recorded in January month (55.19±0.00) during winter
season as compared to other months and seasons.
Table (1): Mean±SD Values of Maximum and Minimum Temperature and Relative
Humidity During Study Months Period.
Min.RH
(%)
Max. RH
(%)
Min.Temp
(ºC)
Max.Temp
(ºC)
Months
July 47.63±1.44a 28.40±1.13a 26.03±3.14e 7.26±2.25f
August 47.46±1.43a 27.16±1.01a 38.40±1.79d 16.93±3.90d
October 35.87±1.38b 19. 00±1.48b 44.06±2.48c 11.12±2.01e
November 27.53±0.86c 12.50±0.62 c 69.33±4.64b 21.30±1.64c
January 19.90±1.39e 5.74± 0.85e 72.09±5.17a 24.29±1.67b
February 21.75±1.87d 10.28±1.38d 71.21±2.79a 26.71±1.86a
LSD 1.84 1.23 1.88 2.42
Mean THI value with different superscripts (a, b,c,d,e and f) in the column differ significantly (P≤0.05).
(Basrah Meteorological Center 2018-219)
Table (2): Mean±SD Values of Monthly Average Temperature and Relative
Humidity During Study Months Period.
Average . RH
(%)
Average. Temp
(ºC)
Months
July 38.16±0.79a 16.90±2.13d
August 37.31±0.94b 27.66±2.22c
October 27.43±1.03c 27. 59±1.68c
November 20.01±0.51d 45.33±2.32 b
January 12.82±0.92f 48.32± 3.23a
February 16.01±1.15e 48.96±1.77a
LSD 0.85 2.98
Mean THI value with different superscripts (a, b, c, d, e and f) in the column differ
significantly (P≤0.05). (Basrah Meteorological Center 2018-219)
Table(3): Mean ±SD Values of Average Temperature Humidity Index (THI) During the
Study Months and Seasons Period.
Months Average
THI
Season Average
THI
July 83.66±0.27b Summer 84.44±0.86a
August 85.22±0.41a
October 77.87±0.00c Autumn 69.17±8.92b
November 60.48±0.00d
January 55.19±0.00f Winter 55.85±0.68c
February 56.52±0.00e
LSD 1.33 LSD 13.32
Mean THI value with different superscripts (a, b, c, d, e and f)in the column differ significantly (P≤0.05).
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2-Effect The Thermal Stress on Respiratory Rate, Heart Rate and Rectal
Temperatures Values In Holstein Calves During Months and Seasons of Study
Period.
The effect of variation weather (ambient temperature value and humidity
percentage) during different months and seasons on heart rate, respiratory rate and
rectal temperature explained in a Table (4and5). There was significant increase (
P≤0.05) in heart rate in both months August and July as summer seasons than the
October, November months (Autumn season) and January and February months
(winter season). Significant (p≤0.05) increase of respiratory rate was recorded during
August months and summer season as compared to the rest months and season.
While, during January month and winter season the respiratory rate was significantly
(p≤0.05) decrease. During August month, the rectal temperature value was
significantly(p≤0.05) increase than others months but did not recorded any varied
among the different seasons.
Table(4): Effect the Thermal Stress on Respiratory Rate, Heart Rate and Rectal
Temperature Values in Holstein Calves During Months of Study Period, (Mean ±SD.,
n=20).
Months H.R(Beat/min) R.R(Breath/min) R.T(ºC)
July 83.60±1.26a 46.60±6.67b 38.52±0.07b
August 86.20±2.04a 49.90±6.67a 38.64±0.07a
October 73.50±2.91b 39.30±2.90c 38.36±0.08c
November 67.80±2.14c 27.80±2.61d 38.34±0.06cd
January 60.60±0.84d 17.30±0.94e 38.25±0.05d
February 64.80±2.52c 18.70±0.82e 38.27±0.04cd
LSD 5.00 2,20 0.11
Values express as mean ± SD., n = 20 calves. with different superscripts (a , b,c,d,e) in the column differ
significantly (P≤0.05).
Table(5): Effect The Thermal Stress on Respiratory Rate, Heart Rate and Rectal
Temperature Values in Holstein Calves During Seasonal Period,
(Mean ±SD., n=20)
Season H.R(Beat/min) R.R(Breath/min) R.T(ºC)
Summer 84.90±2.12a 48.25±6.71a 40.83±10.11
Autumn 70.65±3.84 b 33.55±6.48b 38.35±0.76
Winter 62.70±2.83c 18.00±1.12c 38.26±0.50
LSD 7.95 14.70 NS
Values express as mean ± SD., n = 20 calves. with different superscripts (a,b and c) in the column
differ significantly (P≤0.05).
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3-Effect The Thermal Stress on Oxidant and Antioxidant Statute Value in
Serum Holstein Calves During Months and Seasons of Study Period
Table (6 and 7) Show the effect of thermal stress on antioxidant statute in serum
Holstein calves during different months and seasons. The results revealed a significant
increase (p≤0.05) in MDA , SOD, GPX and CAT in July and August summer months
as compared to other months and seasons.
Table (6): Effect of Thermal Stress on Value of MDA, SOD, GPX and CAT in
Holstein Calves During Months of Study Period, (Mean ±SD., n=20).
Months MDA(U/L) SOD (U/L) GPX (U/L) CAT (IU/ml)
July 3.94±0.56a 60.65±1.28a 331.40±17.80a 2.77±0.43a
August 3.94±0.60a 60.65±1.28a 333.06±19.97a 2.97±0.51a
October 3.15±0.54b 55.63±0.66b 290.57±22.05b 2.53±0.30b
November 3.05±0.13b 44.7±6.50c 290.57±22.04b 2.29±0.27b
January 2.34±0.34c 36.90±3.51d 273.62±12.17c 1.99±0.36c
February 2.43±0.36c 36.89±11.3d 274.45±3.31c 1.98±0.42c
LSD 0.62 5.02 16.94 0.43
Values express as mean ± SD., n = 20 calves, with different superscripts (a, b,c and d) in
the column differ significantly (P≤0.05).
Table (7): Effect of Thermal Stress on Value of MDA, SOD, GPX and CAT in
Holstein Calves During Seasonal Period, (Mean ±SD., n=20).
CAT
(IU/ml)
GPX
(U/L)
SOD
(U/L)
MDA
(U/L)
Season
Summer 3.94±0.57a 60.41±1.34a 332.23±18.43a 2.87±0.47a
Autumn 3.10±0.38b 50.17±7.18b 290.04±21.46b 2.41±0.30b
Winter 2.39±0.34c 36.89±8.18c 274.57±8.69c 1.98±0.38c
LSD 0.71 10.24 16.53 0.42
Values express as mean ± SD., n = 20 calves ,with different superscripts (a,b and c) in the column
differ significantly (P≤0.05).
4-Effect The Thermal Stress on Hormones Profiles in Serum Holstein Calves
During Months and Seasons of Study Period
On the basis on the results that clarified in Table (8 and 9), revealed a significant
decrease (P≤0.05) in serum Testosterone, T4 and T3 levels during July and August
month of summer season than the other months and season, where its recorded high
significant in January and February months of winter season. While serum cortisol
level recorded high significant (P≤0.05)in both months and summer season as
compared to other months and seasons.
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The serum Insulin concentration was not recoded any significant (P˃0.05) changing
among different months of the experimental in Table(8). During winter season, the
serum Insulin level was significantly (p≤0.05) higher than the autumn and summer
season in Table (9).
Table(8): Effect The Thermal Stress on Testosterone, Cortisol, Insulin, Thyroxin(T4),
and Triiodothyronin(T3) Hormones level in Holstein Calves During Months of Study
Period, (Mean ±SD., n=20).
T3
(ng/ml)
T4
(ng/ml)
Cortisol
(nmol/l)
Insuline
(μIU/ml)
Testosterone
(ng/ml)
Months
July 11.02±3.16c 17.88±0.73 17.21±1.20a 3.66±0.33c 0.74±0.10c
August 10.12±0.55c 17.89±0.72 18.58±0.56a 3.43±0.27c 0.71±0.08c
October 10.65±0.40c 18.06±0.81 16.18±1.45b 3.41±0.34c 0.71±0.09c
November 11.97±0.55b 18.14±0.85 13.47±1.77c 5.56±0.54b 0.87±0.13b
January 13.71±0.79a 20.00±0.60 12.45±1.56c 6.69±0.52a 1.07±0.18a
February 13.57±0.72a 19.92±0.62 11.82±1.43c 6.70±0.49a 1.17±0.15a
LSD 0.92 NS 2.84 1.12 0.12
Values express as mean ± SD., n = 20 calves ,with different superscripts (a,b and c) in the column differ
significantly (P≤0.05), NS: non- significant.
Table (9): Effect of Thermal Stress on Testosterone, Cortisol, Insulin, Thyroxin and
Triiodothyronin Hormones level in Holstein Calves During Seasonal Period, (Mean
±SD., n=20).
Values express as mean ± SD., n = 20 calves ,with different superscripts (a, b and c) in the column
differ significantly (P≤0.05).
5-Effect of Thermal Stress on Serum Hsp70 level in Holstein Calves During
Months and Seasons of Study period
On the basis on the results that clarified in Table (10), revealed a the serum HSP70
level varied between different months and seasons. Which recorded highest
significant (P≤0.05) in July and August months of summer season while recoded
lowest significant in both January and February months of winter season than the rest
months and seasons.
T3
(ng/ml)
T4
(ng/ml)
Cortisol
(nmol/l)
Insuline
(μIU/ml)
Testosteron
e
(ng/ml)
Seasons
Summer 10.18±0.81b 17.89±0.70c 17.89±1.15a 3.54±0.32c 0.73±0.09c
14.82±2.10 4.48±1.18b 0.79±0.14b
b
18.10±0.81
b
Autumn 11.31±0.82b
Winter 13.64±0.74a 19.96±0.6a 12.14±1.49c 6.69±0.49a 1.12±0.17a
LSD 2.33 0.37 2.68 0.94 0.33
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Table(10): Effect of Thermal Stress on Value of Serum Hsp70(ng/dl) In Holstein
Calves During Months and Seasons of Study Period,( Mean ±SD., n=20).
Values express as mean ± SD., n = 20 calves ,with different superscripts (a , b and c) in the column
differ significantly (P≤0.05)
DISCUSSION
It's clear that the THI value recorded significant (P≤0.05) increase at August month
than others month and during summer season and autumn season compared to cold
season which present in the Tables(3), might be due to the elevated the global
temperature and humidity in this month and these season in Basrah governorate. Our
results agreed with (19) who revealed a significant increase of THI value at hot season
than other years season.(20) showed that THI value75 to 80 was moderate to high
power of heat stress, while THI value73-77were considered mild thermal stress and
THI value 72 and underneath was considered as no warmth stress. But, (21)
considered that THI value 78 to 89 as moderate and above 90 as extreme thermal
stress. In this manner, in the current examination the average THI of during the cold
season (winter) demonstrated that the creatures were under no warmth stress. While,
the average THI value throughout the autumn and hot (summer) seasons respectively
showed that the creatures were under moderate to high power of warm pressure at
Basrah governorate.
The weather change has increased significantly, which will significantly affect
animal neuroendocrinlogy, hematology parameter, and different physiological process
(22). The respiratory rate, heart rate rectal temperature recorded greatly significant
(P<0.05) during August month but rectal temperature did not recorded any significant
among different months. While all values recorded high significant in summer season
than autumn and winter seasons, these data like to that reported by (13) in cow. Heat
stress causes many physiological changes in farm animals (23,24). The variation in
number of breath/mint from (2.8 into 3.3) was recorder when ambient temperature
Months HSP70
(ng/dl)
Season Hsp70
(ng/dl)
July 3.14±0.50a Summer 3.21±0.51a
August 3.27±0.53a
October 2.83±0.57b Autumn 2.66±0.53a
November 2.49±0.46b
January 1.51±0.45c Winter 1.52±0.42b
February 1.53±0.41c
LSD 0.44 LSD 1.14
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increased one degree only(25). (26) showed an improved in breathing value as result
of stimulation breathing receptors which transfer signs into respiratory center in
hypothalamus in order to remain acid-base homeostasis. In stressor cattle the
respiratory acidosis was noticed due to decrease the pH of blood and insufficiency of
arterial carbon dioxide (27). Therefore, enhanced the mean of breathing per minute as
increases expiration of CO2 through the lung to decline carbonic acid concentration to
critical balance then causes respiratory alkalosis(28).
Breath/minute is impact by many factors include, age, sex, morphology,
phenotype, nutrition, management and other environment factor(25).Usually,
enhanced the respiration and sweating process were determined once animals were
exposed to harsh climate temperature, in order to eliminate the additional heat load
by cutaneal cooling system (29, 30)
. Historically, circulation of cortisol levels have been direct relation with rectal
temperature and heart beat value in beef calves(31). Other studied referred to the
correlation between rectal temperature value and respiratory rate which considered a
lead to assess in health of function and vital activity (32). So when the rectal
temperature a get higher one degree was accompanied by diminish in animals appetite
and production. Rectal temperature as greater than before in heated stressor cattle
(33).
Calves differs from others animals in the tolerance of harsh heat according to
their anatomical structure, when its rectal temperature increased at stress period
accompanied with set of physiological change(34). Others authors showed that the
Creole goats breed tend to adapt on the region factors which selected in throughout
keep its rectal temperature closely into the normal degree with little variation in pulse
and respiratory rate value(35) while, thick of skin surface and decrease sweat gland
mad buffalo more affected by hostile factors (36).
In different heat stressful buffalo breed their rectal temperature and
respiratory rate were affected at high THI value in Mediterranean breed as compared
to crossbred breed(37) . Furthermore, (38) recorded lower value in respiratory rate,
rectal temperature and pulse rate in silk haired Holstein cow at hot condition than the
normal haired cows. Other research investigated that the elevated levels of thyroid
hormones increment cell breath, ATP generation, cell development, cardiovascular
and respiratory rates and catabolic pathways (39).
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Physiologically, in the present study the Holstein calves might be adapted to
dry and humidity heat condition by enhanced metabolic rate, respiratory rate and
cutaneal cooling mechanism. The pulse rate value in the present study was agreed
with studied by (40), these rise as a result of the relationship within respiratory rate as
the latter promotes blood circulation leading to increase heart beat and thus an
increase in the elimination of heat through the skin surface(41). Increased pumping of
blood from the heart to word the peripheral of blood vessels was investigated to
maintain homoeothermic by(42). A rise in heart rate has been conjointly reported in
heat stressful goat during summer season (43). But (44) showed that the heart beat
decrease when animal enhanced water intake and excreted it throughout their body at
hot period.
In ours study the calves has been exposed to different environmental condition, the
metabolic process and physiological parameters were realized adjustment only when
the calves exposed to hot condition.The our results were obtained in the current
experimental showed that the serum levels of (MDA, SOD, CAT, GPx) in calves have
been affected by variation of THI value during different season. Serum oxidative
agent is higher than in the demand at high value of THI than the low value of it.
MDA has been recorded highest value in August month, thus agreement with (45)
indicated that the combination changes of climate temperature degree and relative
humidity are stimulate peroxidation process of poly unsaturated fatty acid,
successively thus the MDA is taken a main signs for oxidative stress. High and low
value of THI had been negatively affect with imbalance of oxidative and anti
oxidative status, previous rumored by(46).
This result agreement with the study of (47) in calving cows showed significant
decline in blood MDA level at high global temperature during summer season than
the winter season. Hence, MDA plasma level reduced significant in winter than
summer season(48) While, other investigators showed that the plasma oxidative had
been recorded high value in cow at low ambient temperature(49).
The conducted research showed that activity of enzymatic antioxidant
superoxide dismutase (SOD), catalase (CAT), and glutathione peroxides (GPx) were
significantly higher at winter period in comparison with other period. This obtained
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uncorroborated with (50,51). Also, (52,53) indicated to direct relation between high
value of THI within plasma superoxide dismutase (SOD) and catalase (CAT) levels
in buffaloes and cattle respectively. Furthermore, low significant in erythrocyte
catalaes (CAT) and superoxide dismutase (SOD) enzymes were noticed in Halliklar
cows during winter season compared to rainy and summer seasons (54).
Catabolism hormones had been negatively effect on SOD and GPx in hottest cow
and goat (55) respectively. Metabolic process in cattle are affected at high ambient
temperatures due to increased production of free radicals and decrease in the secretion
of thyroid hormone, subsequently this explained the association between blood level
of hydrogen peroxides and the low secretion of thyroid hormones with hot
weather(56). Reduced feed intake at hot condition in addition to increase discharge of
catabolism hormone (cortisol) assume a significant job in raised the generation of free
radicals and ROS and exhaustion of anti oxidants status through expanded lipolysis
process (45).
In Holstein calves during experimental study month of the years were recorded
decrease significantly (P<0.05) in summer months and season contrasted with other
months and seasons. This result may be because of brought down body metabolic
rate during summer months which is required to keep up balance between heat
generation and heat dispersal during summer pressure. In the animal exposed to
excessive ambient temperature (57) had a look at that have an influence of high
ambient temperature on the lowering discharge of thyroid hormones because of the
impact of excessive temperature on pituitary thyroid peripheral tissue axis (PTA)
which in flip is prompted reduction in the basal metabolism rate as compared to the
animal covered to low ambient temperature.
While, (58)explained the reason for the decline of hormones during the
summer season, especially thyroxin, due to decline synthesized of this hormone by
thyroid follicle cell which lead to decreased accessibility of thyro-peroxidase protein
which required for oxidation of iodide particles to frame iodine molecules as a great
part of the chemical movement is associated with catalyzing H2O2 created summer
pressure.
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The thyroid gland activity is reduced even as the animal is uncovered to hot
conditions and multiplied while exposed to cold, well-adapted animals reply quickly
to environmental modifications and as a consequence could make the vital
physiological adjustments. While, (39) investigated that the discharge of tropic
hormones is influenced at the point when a creature is exposed to high encompassing
temperatures, emission of those hormones is repressed so as to keep away from
thermogenesis.
The serum cortisol concentration in our study recorded high significant in
August month as compared to others month its recorded high significant (P<0.05)
during summer season as compared to autumn season and winter season. This study
conducted with studied by (54) in Hallikar cattle. In our study, an enhanced the level
of COR mitigated the damage of the safe organs and the confusion of protein
metabolism in calves at heat pressure.
Our study is un concurrence with different investigations that have announced
cortisol decline a few days after heat pressure(59). Other result was described that
elevated air temperature caused enhanced in plasma cortisol level and in rectal
temperature value in beef cattle, which initiate the activity of heat shock protein
(HSPs) to control cell suitability against heat(60).
The serum insulin concentration in our study change value in January to July
months of year and did not recorded any significant among different months. This
study agreement with study by (61) observed there was no significant in plasma
insulin level in dairy cows when exposure to cold and heat stress. But, disagreement
with result by (62) who recorded high significant in insulin value at both dry hot
weather and humid hot weather in buffalo as compared to cooling one.
The concentration of testosterone hormone in Holestin calves during
experimental study different months and different season of the year in( Table (8 and
9). The concentration of testosterone hormone our study change in July and August,
in October and November to January and February months respectively and its
recorded decrease significant (p<0.05) during summer season as compared to autumn
season and winter season. The our data agreement with results obtained by other
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Bas.J.Vet.Res.Vol.19, No.2, 2020.
research such as (63) in their study on decline level of testosterone hormone under
heat factor, and (64) explained the reason of its decline might be due to decline
synthesis of it or enhanced metabolism of it by liver.
(65) investigated that the decline in the level of testosterone hormone,
furthermore affected of testicular function is inverse related with high
concentration of serum glucocorticod. This study disagreement with result related by
other researchers such as (66)in their study on effect the high and moderate
temperature in lamb.
In Table (10), there was a significant effect of months, seasons and variation
value of THI on serum Hsp70 level in Holstein calves during experimental study
months and different seasons of the years. This result has been recorded high
significantly (P<0.05) on Hsp70 level in August month compared to others month and
high significant in summer season contrasted with other season because the dynamic
of Hsp70 with an expansion in stress factor demonstrated that the first security to the
cells/body against the heat pressure for protecting any basic and useful harm to the
cell, and this study consistent with previous study by many authors such as (67).
The elevated level of Hsp70 could be used as a main indicator for change in body
temperature when it is more than 38.6ºC (68), Therefore, the high level of Hsp70 in
summer season than other season in our study was agreed with studied by (33) in
Buffalo. Wherever, (69) detailed higher articulation of Hsp70 during summer than
winter season in goat breeds.
Plasma concentration of Hsp70 is strongly associated with ambient temperature
but not with body temperature of animals owing to intermediate messengers that
respond to changes in ambient temperature leading to increased transcription of HSP
(69).Under heat condition, HSP are activated and save the cell by minimizing
accumulation of the denatured or abnormal proteins in the cell. In this way, they
enhance the cell. Cellular proteins are adversely affected by heat stress except HSP,
which are activated by heat shock.
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فی ذکور HSP تأثیر الإجھاد الحراری على بعض الصور الفسیولوجیة و الصمیة و
العجول المحلیة
جنان عبد الخضر ھلال ، منى حمید محمود السعید
فرع الفسلجة والأدویة والکیمیاء الحیاتیة ، کلیة الطب البیطری جامعة البصرة ، البصرة، العراق
الخلاصة
ث رة حی ة البص أجریت ھذه الدراسة فی حقل لتربیة الأبقار فی القطاع الخاص بمنطقة القرنة شمال محافظ
ھری یف ش م الص ة ، موس م التالی منت المواس باط ٢٠١٩ وتض ى ش وز ٢٠١٨ إل ین تم ا ب رة م ی الفت ت ف أجری
تاء م الش ام ٢٠١٨ ) وموس ن ع وفمبر م وبر ون ھری( أکت ف ش م الخری ام ٢٠١٨ ) ،موس (تموز وأغسطس من ع
یم ض الق ى بع عل THI ة أثیر قیم ن ت ف ع ة للکش ذه التجرب ممت ھ ام ٢٠١٩ ).ص ن ع شھری( ینایر وفبرایر م
ى الفسیولوجیة والھرمونیة على الذکور لعجول ھولشتاین المحلیة عدد ٢٠ حیث تراوحت اعمارھم مابین (سنة ال
ات ى درج ة ال سنة وثمانیة اشھر) حیث تم جمع عشرین عینة دم شھریًا من الذکور لعجول ھولشتاین المتعرض
ة ن قیم ل م ی ک ف (P≤ وی( 0.05 اع معن ائج ارتف رت النت ة. اظھ م المختلف ھر والمواس الحرارة والرطوبة فی الأش
ة معدل التنفس ، ومعدل ضربات القلب اذ سجلت ارتفاع معنوی فی شھور وموسم الصیف باستثناء درج ، THI
ادات جلت مض ا س ة. کم م المختلف ین المواس ب (P˃ وی ( 0.05 رق معن ر أی ف م تظھ ی ل تقیم والت رارة المس ح
یف م الص ھر وموس لال أش خ (P≤ ة ( 0.05 ة ملحوظ ادة معنوی زی GPX و SOD, CAT, MDA دة الاکس
ورتیزول و فی مستوى ھرمون الک (P≤ مقارنة بأشھر وموسمی الخریف والشتاء.لوحظ ایضا ارتفاع کبیر ( 0.05
ی اض ف وحظ انخف ا ل م. کم یف والموس ھر الص لال أش خ HSP ة 70 دمة الحراری روتین الص توى ب ی مس ف
وظ کل ملح بش (T ودوثیرونین ( 3 ی ی وثلاث (T ة ( 4 دة الدرقی ون الغ تیرون وھرم ون التستوس تویات ھرم مس
ی ولین ف خلال أشھر وموسم الصیف مقارنة بالأشھر والمواسم الاخرى ، لکن مستوى ھرمون الأنس (P≤0.05)
خلال موسم الصیف مقارنة بالمواسم الاخرى. (P≤ الدم أظھر انخفاضًا ملحوظًا ( 0.05
44
Bas.J.Vet.Res.Vol.19, No.2, 2020.
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