Lead Toxicity in Mute Swans

i
Though lower values were recorded in this study the 1 f
, ower re erence
limits did not drop below 29.00 g/ lOOmls (Table 1).
While in lead
poisoned birds (Table 6), and moulting birds the values of MCHC are
lower.
Thus when considering MCHC, the physiological state must be
noted before any diagnosis is made.
Fifteen other blood parameters were measured to establish reference
distributions (Table 2).
The details of the data were not broken down
to individual sexes since the number of specimens would not allow
sufficent precision in the estimates of percentiles (Solberg, 1983).
The decision to include all the specimens in the reference distribution
is substantiated by the fact that many of the blood parameters
conformed to a Gaussian distribution.
The recorded values for the
various blood constituents are close to those reported for other
species
(Freeman, 1984), though levels of cholesterol are higher than
in chickens, while levels of glucose and sodium are lower (Sturkie,
1965; Panigahy et al., 1986)
There was a wide range of values for protoporphyrin.
Bush et al.,
1982 suggest that values of protoporphyrin greater than 1.07 uM/l are
indicative of lead poisoning in humans.
Roscoe (1979) selected a more
conservative value of 0.70 uM/L (40ug/100mls) in ducks,
to distinguish
lead poisoned birds.
In the present study,. values of protoporphyrin
ranged from 0.10-1.20 uM/L (Table 2) for 95% of the normal values, with
a maximum value of 1.60 uM/L in one healthy cygnet (Table 2).
The
importance of relating protoporphyrin to haemoglobin content has been
neglected by many workers. Chisolm, 1973 and Chisolm et al. (1974)
reports that 'strictly speaking the whole blood fluorescence should be
corrected for haematocrit or haemoglobin'.
Thus, the corrected
reference distribution for protoporphyrin IX (Table 2) should be
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