Trakia Journal of Sciences, Vol.1, No 1, pp 61-66, 2003
Copyright © 2003 Trakia University
Available on line at:
http://www.uni-sz.bg
Original Contribution
CLINICAL EXPERIMENTAL STUDIES ON ACUTE RUMEN ACIDOSIS IN
SHEEP WITH A PREEXISTING CHRONIC LEAD AND
ORGANOPHOSPHORUS COMPOUND INTOXICATION.
II. BLOOD BIOCHEMISTRY CHANGES
Yordan Nikolov*
Department of Internal Diseases and Clinical Toxicology, Faculty of Veterinary Medicine, Trakia
University, Stara Zagora
ABSTRACT
Experiments were performed on 15 sheep divided into 2 groups (A-7 animals; B-8 animals) in order to
monitor the changes some biochemical parameters in chronic lead and pesticide intoxication followed
by acute rumen acidosis. A chronic lead and Fosdrin 24EK intoxication was provoked in both groups
via administration of lead acetate at a dose rate of 15 mg/kg body mass and 3.5 mg/kg body mass of
organophosphorus insecticide Fosdrin 24EK (2-carbomethxy-1-methylvinyl-dimethylphosphate) once
weekly, 2 hours after morning feeding for 6 months. Before treatment of experimental groups with the
toxic combination, blood samplings were performed in 15-day intervals, and after the beginning of the
experiment on a monthly basis until the end of the 6th month, for determination of blood sugar,
piruvate, lactate, urea-nitrogen and bilirubin rate. At the end of the 6th month, acute rumen acidosis
was provoked in group B sheep via the administration of 20 ml/kg body mass beet molases containing
540 g/l saccharose. Biochemical parameters were followed out in dynamics at hours 2, 6, 10, 12, 20
post-treatment and compared with group A sheep. It was concluded that the chronic lead and pesticide
intoxication had no influence upon blood sugar, lactate and piruvate concentrations, but blood urea
and bilirubin were increased. The provoked acute rumen acidosis changed their values as early as the
6th hour leading to lacticidemia, bilirubinemia, increase in blood urea and piruvate levels.
Key words: Intoxication, Chronic, Lead, Pesticide, Rumen acidosis, Lactic acide, Bilirubin, Blood
sugar
INTRODUCTION
The accumulation of heavy metals from a
technogenic origin in soil, plants and animals
(humans) has been studied by many
investigators (1, 2, 3, 4).. The intensive
development of metallurgy in some countries
creates prerequisites for environmental
pollution with an extent of more than 20 km
over agricultural lands and settlements. The
continuous increase in heavy metal content
(lead, cadmium, arsenic, zinc, copper and
mercury) in soil and hence, in plants and
domestic animals (men) is an attractive
subject for veterinary science (2, 5, 6). The
toxic impact of lead upon human and animal
health is determined by its presence in
*Correspondence to: Yordan Nikolov, Dep. of Internal
Diseases and Clinical Toxicology, Faculty of Veterinary
Medicine, Trakia University, 6000 Stara Zagora,
Bulgaria, tel.: +359 42 28012652, E-mail: dnik@abv.bg
industrial aerosols around plants processing
polymetal ores, battery, motor oils and dye
industries, oil refineries and automobile
transportation (7, 8, 9). This is the principal
cause for the more frequent reports about
acute and chronic intoxications among both
workers in such enterprises and men and
animals inhabiting adjacent regions (1, 6, 10,
11).
The application of a wide range of
chemicals as pesticides against pathogenic
agents of both plants and animals in
agriculture increases the yields and the
productivity but their careless manipulation
results in environmental pollution.
Phosphoorganic insecticides are among the
most commonly used in plant protection and
thus, they are a potential cause for massive
acute and chronic intoxications. The toxic
effect of those pesticides in the course of
acute and chronic intoxications is well known
61
Y. NIKOLOV
in Bulgaria and abroad in laboratory and some
farm animals (11).
The environmental pollution with heavy
metals and pesticides in some cases result in
severe and continuous ecological catastrophes
and permanent ecosystem disbalances. Some
aspects of the impact of the continuous
independent
ingestion
of
lead
and
phosphoorganic insecticides in ruminants are
studied in our and other countries. Now
however, living organisms are submitted to a
systemic influence of small doses of heavy
metals and pesticides, resulting in chronic
damage of organs and systems, clinically
manifested by late effects (embryotoxicity,
teratogenicity, mutagenicity etc.), decrease of
systemic resistance against bacterial and viral
infections etc. (6, 12, 13, 14, 15). Moreover,
the studies in this connection are incomplete,
lacking or contradictory.
One of the most common indigestion in
ruminants, both in co-operative and private
farms, caused by an excessive feeding of diets
containing easily digestible carbohydrates, is
rumen acidosis (17, 18, 19). It causes
considerable economical losses through
decreased productivity (milk, weight gain
etc.), decrease of populations because of the
increased death rate, physico-chemical
alterations of foodstuffs from animal origin
etc.
Some aspects of the aetiology of the
disease, laboratory analysis of blood, rumen
content and urine has been studied in cattle,
sheep, goats and buffaloes with rumen
acidosis (18, 19, 20, 21).
At the background of the chronic lead and
pesticide intoxication, the inducement of
acute rumen acidosis gives an idea about the
degree of damage of the animal organism and
its resistance  points with no reference in
available literature.
Previous studies of ours (11, 14, 15, 22)
show that the simultaneous intoxication with
lead and pesticides in sheep provoked severe
systemic disorders for a period of 6 months.
The changes occur in both the clinical and
haematological status. On the background of
this chronic intoxication, the acute rumen
acidosis further aggravates the pathology and
resulted in lethal issue in a different period of
time (3, 11, 12, 13, 19, 23, 24).
The present report aims to follow out the
changes in some blood biochemical
parameters in order to elucidate the
pathogenesis of such combined intoxications
in sheep.
62
MATERIALS AND METHODS
The experimental studies were performed
with 15 Merino sheep weighing 55-62 kg,
aged 5-6 years divided into 2 groups - A (7
sheep) and B (8 sheep). Both groups were fed
and housed similarly.
The chronic lead and pesticide intoxication
in both groups was provoked via
administration of lead acetate at a dose rate of
15 mg/kg body weight and 3.5 mg/kg body
weight of the organophosphorus pesticide
Fosdrin
24EK
(2-carbomethoxy-1methylvynil-dimethylphosphate) once weekly
for 6 months, 2 hours after the morning
feeding. The doses were individually
calculated for each animal. Both compounds
were applied dissolved in 0.5 l water via a
stomach tube. Before the treatment of
experimental groups with the toxic
combination, blood was sampled thrice from
v. jugularis in 15-day intervals for the
determination of lactate and piruvate
concentrations (25); blood sugar, urea and
bilirubin (automated biochemical analyser
Reflotron - manuel, Germany).
After the beginning of the lead acetate and
Fosdrin 24EK treatment, blood for
determination of forementioned parameters
was sampled once monthly up to the end of
the 6th month. The acute rumen acidosis was
provoked at the end of the sixth month in the
second group of sheep through the
administration of 20 ml/kg body mass beet
molasses containing 540 g/l saccharose. The
molasses was given dissolved in 0.5 l of water
via a stomach tube. Blood sampling and
analysis were performed in dynamics at hours
2, 6, 10, 12, 20 posttreatment in both groups
of sheep. The statistical analysis of data was
performed using the t-test at a level of
significance 0.05.
RESULTS
The results for the estimated parameters
during the different periods of the study are
presented in Table 1. It was found out that the
values from the triple control determinations
were within the reference ranges. During the
development of the chronic lead and pesticide
intoxication, lactate concentrations varied
statistically insignificantly over the baseline
values up to the end of the 6th month (1.1±0.1
mmol/l). Piruvate and blood sugar levels
showed a tendency toward slight increase at
the end of the experiment (month 6; 53.3±3.4
µmol/l and 3.9±0.2 mmol/l respectively).
Bilirubin concentrations in both groups were
Trakia Journal of Sciences, Vol.1, No 1, 2003
Y. NIKOLOV
rd
progressively increased from the 3 month
onward (p<0.05) and reached 6.3 – 6.7 µmol/l
(p<0.001) at the end of the 6th month. Blood
urea showed the same pattern of change from
the 4th month onward (p<0.05) and reached
11.1-11.3 mmol/l (p<0.001) at the end of the
6th month (Table 1).
After the onset of the acute rumen
acidosis, on the background of the chronic
lead and pesticide intoxication, the systemic
metabolic changes worsened. At day 180 from
the beginning and at posttreatment hours 2, 6,
10, 12, 20 the following changes in the sheep
from the 2nd group were recorded: lactate
concentrations increased as early as
posttreatment hour 6 (3.8±0.2 mmol/l;
p<0.05) and reached 6.8±0.5 mmol/l
(p<0.001). Piruvate and blood sugar levels
increased from hour 6 onward and reached
110.1±6.2 µmol/l
and 8.3±0.2 mmol/l
respectively (p<0.001) at posttreatment hour
20. Bilirubin and urea values increased from
the 10th hour onward (p<0.05) up to 8.9±4
mmol/l (urea) and 14.6±0.9 µmol/l (bilirubin)
(p<0.01).
DISCUSSION
Our studies showed that the prolonged
treatment of sheep with lead acetate and
Fosdrin 24EK at the chosen dose rates
provoked chronic disorders. There occurred
systemic dystrophic and degenerative changes
in liver cells structure with impairment of
their function (2, 6, 10, 14, 18, 21, 22, 26), i.e.
the metabolism of blood sugar to glycogen.
After the onset of the acute rumen acidosis,
the easily digestible carbohydrates (molasses)
were metabolized to propionic, acetic, butyric
and particularly lactic acids in the rumen (17,
19, 20, 24, 26). They were resorbed in blood
under the form of lactates and acetates
resulting in increase in lactate concentrations
(6, 17, 19, 20, 24). During the first few hours
of the acute rumen acidosis, the organism
compensates the lacticidemia via its buffer
compensatory mechanims, so a compensated
metabolic acidosis was observed (10, 17, 20,
26).
Later, those possibilities were spent and
the animals passed in a state of
decompensated metabolic acidosis with
average blood lactate concentrations of
6.8±0.5 mmol/l.
The increased amount of serum piruvate
during the development of the chronic lead
and pesticide intoxication and further during
the acute rumen acidosis was due to the
inhibition of the piruvate decarboxylase thus
preventing the metabolism of piruvate in
oxalacetate and its participation in the Krebs
cycle (8, 17, 18, 20, 22). The increased blood
serum urea was probably due to the renal
damage (intracapillary glomerulonephritis) (3,
5, 13, 18, 22, 27) during the lead and pesticide
intoxication. This increase was an early sign
of renal insufficiency (9, 12, 18, 19, 22, 24).
The increased amount during the acute rumen
acidosis was related to the increased release
of ammonia in rumen and blood (3, 13, 19,
24). Later, a part of ammonia was included in
the ornitine cycle and metabolized in urea as a
waste product (7, 18, 19, 22, 24).
The liver parenchyme dystrophy in the
chronic intoxicated animals prevented the
release of direct bilirubin with the bile. The
permeability of liver cells and the biliary
capillaries was significantly increased and led
to the accumulation of direct bilirubin in
blood. The observed bilirubinemia was also
due
to
impaired
transformation
of
haemobilirubin to cholebilirubin because of
the damaged liver parenchyme (3, 12, 14, 15,
18, 22, 23). At the background of the double
(lead and pesticide) intoxication, the acute
rumen acidosis intensified the dystrophic
processes in parenchyme organes through the
obtained metabolites (lactic acid, histamine
etc.). That is why the detoxication ability, the
extcretory, protein and other functions of liver
were further impaired (1, 17, 19, 24, 28).
CONCLUSIONS
In conclusion, we could say that our complex
experimental studies upon the chronic lead
and pesticide intoxication followed by acute
rumen acidosis, performed for the first time in
sheep, showed an impairment of systemic
metabolism. Blood biochemical parameters
were positively related to the degree of liver
and renal damage. The combination of
chronic (lead and pesticide) intoxication
provoked a double (accumulated) effect upon
the systemic functions. On this background,
the course of the acute rumen acidosis was
severe, with a lethal issue and expressed
blood biochemical changes.
Trakia Journal of Sciences, Vol.1, No 1, 2003
63
Parameters
Lactic
acide
(mmol/l)
Pirovate
acide
(µmol/l)
Blood
sugar
(mmol/l)
Bilirubin
(µmol/l)
Ureanitrogen
(mmol/l)
ap<
group
Table 1. Changes of the lactIc acid, piruvat acid, blood sugar, bilirubin and urea-nitrogen of the blood of sheep with acute rumen acidosis after chronic leadorganophosphorus compound
intoxication.
-30
D a y s
-15
0
P e r i o d
o f
i n v e s t i g a t i o n
M o n t h s
1
2
3
4
5
6
2
6
H o u r s
10
12
20
A 0.7±0.1
0.8±0.2
0.9±0.3
0.6±0.2
0.9±0.1
0.8±0.2
0.5 ±0.2
0.9±0.1
1.0±0.2 1.1±0.1
0.9±0.1
0.8±0.3
0.8±0.2
0.7±0.3
B
0.6±0.1
0.7±0.2
0.8±0.1
0.6±0.3
0.9±0.1
0.9±0.2
1.4±0.2
1.1±0.1 1.2±0.1
3.8±0.2 à
4.2±0.4 c
5.5±0.3 c
6.8±0.5 c
0.5±0.2
A 49.1±1.1 48.2±3.2 52.2±2.2 48.2±1.4 46.1±1.3 48.3±3.2 51.2±3.1 52.1±3.2 53.3±3.4 52.4±4.1 53.2±3.8 51.2±3.9
52.6±4.1 52.1±3.4
B 50.2±2.1 52.1±3.1 49.3±3.3 51.3±2.3 48.1±2.9 52.1±2.1 51.3±2.8 51.9±2.4 52.3±2.9 65.1±4.1 72.8±4.3 à 87.3±5.4 b 98.8±4.3 c 110.1±62 c
A 3.1±0.2
3.3±0.1
3.3±0.2
3.2±0.1
3.5±0.2
3.6±0.3
3.5±0.1
B 2.9±0.1
A 3.2±0.4
B 2.9±0.4
3.1±0.2
2.9±0.1
3.1±0.3
3.2±0.1
2.8±0.3
2.9±0.4
3.3±0.2
3.3±0.5
3.4±0.3
3.3±0.1
3.9±0.4
3.8±0.6
3.0±0.2
4.8±0.5à
4.9±0.3 à
3.4±0.2 3.6±0.3 3.7±0.4 4.4±0.3
4.7±0.4 à 5.4±0.3 b 6.3±0.4 c 6.3±0.2
5.5±0.4 b 5.7±0.2 b 6.7±0.3 c 6.8±0.3
4.9±0.4 à 6.4±0.3 b
6.1±0.1 6.2±0.2
6.9±0.4 7.0±0.5
6.8±0.4 b 8.3±0.2 c
6.3±0.4 6.3±0.5
7.9±0.1 à 8.9±0.4 b
A 7.2±0.2
7.4±0.4
7.1±0.5
7.4±0.3
7.6±0.4
8.9±0.5
9.7±0.2 à 10.6±0.3 b 11.1±0.6 b 11.3±0.7 10.9±0.6 10.8±0.5
11.2±0.4 11.3±0.5
B
7.1±0.3
7.2±0.4
7.5±0.4
7.7±0.5
8.8±0.4
9.6±0.4 à 10.9±0.4 b 11.3±0.7 b 11.5±0.1 12.1±0.6 12.6±0.5 à 13.4±0.8 à 14.6±0.9 b
7.3±0.3
3.8±0.1
3.9±0.2 3.6±0.1
3.5±0.2
0.05 ; b p < 0.01 ; c p < 0.001
Group A (n=7) treated p.o. with lead acetate at a dose of 15 mg/kg body mass and 3.5 mg/kg body mass, Fosdrin 24EK once weekly for 6 months.
Group B (n=8) treated p.o. with lead acetate at a dose of 15 mg/kg body mass and 3.5 mg/kg body mass, Fosdrin 24EK once weekly for 6 months, and the end
of the 6t h month treated with 20 ml/kg body mass beet molasses containing 540 g/l saccharose.
3.7±0.2
3.4±0.1
3.2±0.2
Y. NIKOLOV
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