Haematological studies of alpine crossbreds from birth to puberty
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Date
2003
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Department of Physiology, College of Veterinary and Animal Sciences, Mannuthy
Abstract
Goat (Capra hircus), one of the small ruminant, forms an important
economic and ecological niche in small farm systems and agriculture The blood
constituents differ among animals due to variety of factors viz., species, genetic,
sex, age, growth, environmental and disease conditions. Clinical haematology is
an indispensable adjunct to study the functions of the body in both health and
disease. Haematological parameters are indicators of normal physiological and
health status of an animal. The paucity of information on the haematology of
goats is one of the major constraints in the physiological evaluation including the
adaptability and health status. Besides very little information is available on the
variation of the blood parameters of Alpine crossbred kids from birth to puberty.
Physiological factors like age, sex and the type of management affect
haematological parameters of an animal. Thyroid hormones viz., thyroxine (T4)
and triiodothyronine (T3) are the major regulators of various metabolic functions
in the body. Hence the present study was undertaken to evaluate the .relationship
of age, sex and body weight on these haematological parameters and serum levels
of T, and T3 in healthy Alpine crossbred kids from birth to puberty (six months).
The present study was conducted in 48 Alpine crossbred kids (24 males
and 24 females) of the University Sheep and Goat Farm, College of Veterinary
and Animal Sciences, Mannuthy for a period of six months from day old (on the
day of birth) to six months (puberty) period. The animals were maintained under
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standard managemental conditions.
Body weight of all the animals was recorded on the day of birth and
thereafter at fortnightly during the entire period of study. Blood samples were
collected from all the animals at monthly interval during the six month period.
The blood samples collected with anticoagulant were analysed for
haematological parameters like haemoglobin content (Hb), volume of packed red
blood cell (vpRC), erythrocyte sedimentation rate (ESR), total erythrocyte
(RBC) count, total leucocyte (WBC) count, differential leucocyte count (DLC),
osmotic fragility of erythrocytes and specific gravity (whole blood) using
standard procedures and erythrocytic indices were calculated. The serum
separated from whole blood without anticoagulant was subjected for the
estimation of icterus index and hormonal parameters like thyroxine (T 4) and
triiodothyroxine (T3) using radioimmuno-assay technique. Clinical health status
(respiration rate, pulse rate and body temperature) of all the animals were
monitored at fortnightly intervals.
On age-wise comparison both male and female kids showed significantly
higher values for Hb concentration, VPRC and RBC count at day old which may
be due to the transfusion of placental blood from the dam to the infant there by a
compensatory reduction in plasma volume, leading to higher RBC count, Hb
concentration and VPRC at day old. As the age advanced RBC count, Hb
concentration and VPRC were decreased. Even though the value of ESR did not
reveal any significant difference between age groups an increasing trend was
observed as the age advanced. The velocity of sedimentation of the red blood
ceIIs was inversely proportional to the number of red blood cells. The higher
RBC count at day old may be the reason for a lower ESR value in day old kids in
both sexes. At day old MCV showed lower value in both male and female kids.
As the age advanced MCV showed an increasing trend and finally remained
stable in both sexes. As the kids grew older it is likely that the requirement for
oxygen may be more and with no appreciable change in the number of
erythrocytes, the increased demand for oxygen is met by increased size of the
erythrocytes. The value of MCR did not show any significant difference between
age groups while MCRC value foIlowed a fluctuating trend throughout the six
month period. Minimum and maximum osmotic resistance of erythrocytes did
not show any significant difference between the sex and age groups except for the
females where some differences in maximum osmotic resistance was evident
during the second month. The capacity of erythrocytes to resist osmotic dilution
is related directly to the corpuscle size or MCV. This is in agreement with
the results of present study, that as goats having the smallest RBC, showed signs
of minimum osmotic resistance even in 0.63-0.68 per cent Nacl solution. The
erythrocytes absorb water from the surrounding hypotonic solution and swell
until they reach a maximum size known as critical haemolytic volume after
which haemolysis occurred. The smaller the erythrocyte, the earlier the initial
volume reached. Eventhough specific gravity and icterus index followed a
decreasing trend with age did not reveal any significant difference with age and
sex. Age-wise comparison of total WBC count in both male and female kids
showed an increasing trend with age except the lower value reported at day old
age, though Iymphocyte and eosinophil count were decreased as the age
advanced. In contrast neutrophil count showed an increasing trend as the age
advanced, with the lowest value at day old. The number of monocyte followed a
fluctuating trend without any significant influence of age and sex. As the age
advanced the serum concentrations of T 4 and T 3 hormone showed an increasing
trend with highest value at birth. The level of T4 in the blood represents the
algebraic sum of thyroxine secretion and peripheral utilization. Thyroid
hormones stimulate basal metabolic rate via metabolism of carbohydrates, lipids
and proteins. The increased metabolic demand for oxygen, associated with the
increased body size might have resulted in an increased synthesis and release of
thyroid hormones.
On sex-wise, comparison male kids had higher bodyweight than female
kids throughout the six months period. In the early growing period female kids
possessed higher values for RBC count and Hb content but towards puberty male
kids had the higher values. In male animals testosterone, which has erythroid
stimulating activity led to higher RBC count and Hb content at fifth and sixth
month of age. In female kids, oestrogen might have suppressed the erythroid
activity therefore lower values were observed for the above parameters in the
same age. Erythrocytic indices did not reveal any sex-wise significant difference.
Osmotic fragility of erythrocytes, specific gravity (whole blood) and icterus
index also did not reveal any significant difference between male and
female kids. Lymphocyte count during day old age and first month of age
showed significant difference between sex, while total WBC count and number
of monocytes and neutrophils did not reveal any significant difference between
sex. But the eosinophil count showed significantly higher count for males on the
day of birth only. No basophil could be detected in the blood smear of male and
female kids. The serum hormonal profile of T4 and T3 of male kids showed
significantly higher values than their females throughout the six months period,
justified that the onset of rapid growth was closely related with the onset of
increased serum concentration of T, and T3.
In both male and female kids effect of body weight showed a negative
relationship with RBC count, Hb concentration, VPRC values and lymphocyte
number. In the present study, at birth body weight of male and female kids were
lower. As the age advanced, male and female kids showed a gradual increase in
body weight in all age groups. However, the values of RBC count, Hb
concentration, VPRC, specific gravity (whole blood) and lymphocyte number
showed a higher value on the day of birth and followed a decreasing trend as the
age advanced. This decreasing trend of all the above parameters with an
increasing trend of body weight resulted in a negative correlation between them.
But in both male and female kids effect of body weight showed a positive
relationship with the values of ESR, MCV, WBC count, neutrophil number and
serum T4 and T3 concentration. The increasing trend of all the above parameters
with increasing trend of body weight resulted in a positive correlation.
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