Abstract:
The study was undertaken to assess the effect of various levels of aflatoxin
on the performance of broilers and to establish the permissible level of aflatoxin in
the broiler feed. One hundred and eighty day old broiler chicks were divided into
six groups of 30 birds each and were given feed containing graded levels of
aflatoxin at 0, 20, 40, 60, 80 and 100 ppb for a period of 45 days. Feed intake,
weekly body weight gain, feed efficiency, haemogram, serum profile, organ
weight, residual aflatoxin in tissues and pathological changes in liver, kidney,
bursa and spleen were studied at fortnightly intervals to evaluate its dose related
effects.
A dose dependent decrease in the daily feed intake and mean body weights
were noticed in all the groups. The cumulative FeR was extremely poor at 80 and
100 ppb levels at sixth week of age.
The toxicopathological changes in the birds varied in its intensity in
relation with the level of aflatoxin in the feed, with most severe changes being at
higher dose levels. The values of haemoglobin, PCV, total leucocyte count,
Iymphocytes, total serum protein and albumin showed a decrease whereas the
ESR, heterophil and serum enzyme were increased.
The aflatoxin, even at 20 ppb levels caused degenerative and necrotic
changes in liver and kidneys and the intensity of the lesions increased with higher
levels of toxin. Attempt for regeneration and repair processes were well
pronounced by the 30th and 45th day. Lymphoid depletion was a characteristic
feature in bursa and spleen. Degeneration and lysis of lymphocytes with cys;
formation was also seen in bursal follicles.
Residual aflatoxin was detected in the liver and muscle in all groups by the
45th day. The net returns from the toxin treated birds showed a dose related
decline compared to control and the loss in profit at 20 ppb level was marginal
About 24 per cent of the poultry feed samples tested during the period from
January to July 1999 were contaminated with aflatoxin quantitatively ranging from
20 to 200 ppb.
The results of the present study shows that even at 20 ppb aflatoxin causes
cellular and subcellular damage to the tissues. However, the economic loss at this
level was marginal when compared to higher dose levels. Hence 20 ppb can be
considered as permissible level in broiler chicken feed.
