Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

III. Starvation, Flight, and Postprandial Effects: Circadian and Circannual Rhythms
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decline (10% in 10 min, 30% in 30 min, up to 65% in 2 h) of
plasma potassium concentrations occurs, because of a shift
of potassium ions from the plasma into the red blood cells.
In chickens, decreases were smaller overall with a 29%
decrease being noted after 2 h (Lumeij, 1985a ). In ostriches,
significant increases in plasma potassium concentrations
were observed when blood was stored at 20°C (up to 20%
in 2 h), whereas at 0°C significant decreases were observed
(Verstappen et al. , 2002 ). Many reports on blood chemistry
in birds are based on determinations in serum instead
of plasma or plasma from blood samples that were not centrifuged
immediately. Plasma potassium concentrations
reported herein are often too low.
In suspected lead poisoning, heparinized whole blood
samples should be sent to the laboratory, because the
majority of lead is associated with the red blood cells (see
Section XI.A).
C . Sampling Procedure
In most species, the right jugular vein is the preferred site
for blood sampling. This thick walled vein is less prone to
hematoma formation ( Law, 1960 ; McClure and Cedeno,
1955 ; Stevens and Ridgeway 1966). The medial metatarsal
vein is especially useful for multiple sampling of small
blood volumes in larger birds such as pigeons. Blood can
be collected using a needle and syringe or a blood lancet.
In the pigeon, the jugular vein is not readily visible.
The basilic vein, which is readily visible as it crosses
the ventral aspect of the elbow of all avian species, is the
vein that is traditionally used in poultry. The vein is punctured
with a blood lancet after being swabbed with alcohol
(Gratzl und Koehler 1968). These authors warn against the
use of the comb for blood collection in poultry because the
high risk of exsanguination, especially during cold weather.
In pet birds, the use of a blood lancet for blood collection
from the basilic vein cannot be recommended because this
site is prone to hematoma formation, often even when a
needle is used. The advantage of the basilic vein, on the
other hand, is that it can be located in all avian species.
In ostriches the operator should be aware of the risk of
being kicked. Blood can be collected from the basilic vein
using a sideway approach to the standing animal after it
has been hooded and the wing has been lifted upward by
two assistants ( Fowler, 1978c ). The jugular vein can also
be approached in the same manner.
In ducks and geese, the venous occipital sinus is a good
site for blood sampling ( Vuillaume, 1983 ). It is located at
the junction of the base of the skull and the first cervical
vertebra. Although this site is especially useful for obtaining
large samples, many clinicians will feel more comfortable
using the easily accessible basilic and metatarsal veins
in these species.
Cardiac puncture carries the risk of cardiac tamponade,
and therefore this technique is not recommended for use in
avian clinical practice.
Some individuals choose to clip a toenail to obtain a blood
sample. Disadvantages of this method are that it is painful to
the bird, the sample may become contaminated with tissue
fluids, it may cause damage to the nail bed, and the amount
of blood that can be obtained is limited. Furthermore, contamination
of the sample with urates from the droppings
may give false high readings ( Ekstrom and Degernes, 1989 ;
Rosskopf et al. , 1982 ). For the aforementioned reasons, this
method should only be regarded as a last resort, and the nail
should be thoroughly cleaned before obtaining a sample.
Different bleeding sites (e.g., venous blood versus blood
collected by cardiac puncture) may cause variation in hematological
or biochemical values ( Kern and De Graw, 1978 ).
A vacuum system greatly facilitates blood sampling
from the jugular and basilic veins and from the venous
occipital sinus in Anseriformes. A 3-ml vacuum tube is
sufficient for most cases (Venoject, Omnilabo, Breda,
The Netherlands). For smaller birds, and thus smaller
sample sizes, it is best to use small volume (e.g., 0.5 ml)
Vacutainers (Veterinary Lab Supply, 315 E. Madison,
Winterset, Iowa 50273, United States).
III . STARVATION, FLIGHT, AND
POSTPRANDIAL EFFECTS: CIRCADIAN
AND CIRCANNUAL RHYTHMS
A . Introduction
Some plasma chemical variables are influenced by starvation
or food consumption. Up to 4 days of starvation in
pigeons did not result in hypoglycemia, but rather a starvation
hyperglycemia occurred after 3 days ( Lumeij, 1987b ).
Variables that may have markedly increased values postprandially
are uric acid and total bile acid concentrations.
See Sections V.F. and VI.G ( Lumeij, 1991 ; Lumeij and
Remple, 1991, 1992 ). Furthermore, daily or yearly fluctuations
have also been reported for some chemical variables.
In fasted pigeons maintained on a natural daily 17-h photoperiod
a circadian rhythm was found in plasma glucose
concentrations ( Lumeij et al. , 1987b ) with high values
early during the photophase ( Fig. 28-2 ). Basal plasma thyroxine
concentrations in racing pigeons were significantly
higher in July than in September and December ( Lumeij
and Westerhof, 1988a ). Age, sex, altitude, nutritional status,
and egg laying may also cause variation ( Driver, 1981 ;
Kocan, 1972 ; Kocan and Pits, 1976 ; McGrath, 1971 ; Mori
and George, 1978 ; Simkiss, 1967 ). Effects of long-term
starvation and endurance flight are discussed in Sections
III.B. and III.C, respectively.
B . Biochemistry of Long-Term Starvation
Many avian species depend on catabolism of lipid depots
for survival through the night or winter to enable migratory