null 24. MAKÓOVÁ,Zuzana, SKALICKÁ;,Magdalena, TOMKOVÁ;,Ilona, SVICKY,E., RIMÁR,J.: Chronic effects of aflatoxin B1 on the liver of chickens (Az aflatoxin B1 krónikus hatása tyúkok májára)

24. MAKÓOVÁ,Zuzana, SKALICKÁ;,Magdalena, TOMKOVÁ;,Ilona, SVICKY,E., RIMÁR,J.: Chronic effects of aflatoxin B1 on the liver of chickens (Az aflatoxin B1 krónikus hatása tyúkok májára)

24. MAKÓOVÁ,Zuzana, SKALICKÁ;,Magdalena, TOMKOVÁ;,Ilona, SVICKY,E., RIMÁR,J.: Chronic effects of aflatoxin B1 on the liver of chickens (Az aflatoxin B1 krónikus hatása tyúkok májára)

24. Makóová

érk: 97.10.16.



UEVM, 04001 Kosice, Hlinková 1/A, Slovak Republic(first author's address)
Univ.Vet.Med. Kosice
CHEMKO, Strázske


Health troubles connected with the consumption of feeds contaminated by aflatoxin need not be the consequence of the effect of aflatoxin alone on an organism but they can be a manifestation of the syndromes caused by integrating stress.
At present, the problems of feed contamination by mycotoxins represent very topical problems of poultry breeding. A lot of literary information on mycotoxins from various viewpoints from all over the world testify to their importance and danger. These data are often documenting aflatoxicosis under experimental conditions. In general, the basic products contain 60 to 80 % of provable mycotoxins at low concentrations of 0,1 g.kg-1. Therefore their occurrence has to be taken into account everywhere. It can be said that we live along with mycotoxins. The source of mycotoxins at low concentrations can be foods of plant or animal origin. The animal organism is sometimes able to cope with them without any problems, the larger amounts, however, burden especially the detoxicant capacity of both liver and kidneys.
The effort is to lower the mortality and to improve the health of the poultry breedings affected with aflatoxicosis. It is necessary to solve the problem of the feed contamination by mycotoxins preventively, by the control of their occurrence and subsequent decontamination.
According to present knowledge, using of decontaminant preparations is very effective. Decontaminant preparations manufac tured in the Slovak Republic were tested - i.e. natural ground zeolite (PM, granulation of 0.315 mm) and thermically modified one (PT,CH T granulation of 0.5 mm).
Currently, various preparations for the decontamination of mycotoxins are in use with a sorptive ability (bentonite, zeolite, aluminosilicates, and hydrated calcium-sodium aluminosilicates (HSCAS), activated carbon, specially prepared sorptive compounds, phylosilicate clay).
In Mexico, 6 commercial aluminosilicates for a firm binding of aflatoxin B1 in vitro have been produced. These compounds are still experimentally developing. The efficiency of these specially produced sorptive compounds in vivo has not been fully verified yet.
The objective of this study was to observe morphological changes due to the effect of aflatoxin B1 in broilers at simultaneous administration of natural (PM) and thermically modified (PT) zeolites at the concentration of 0.5% in a feed mixture on production activity and to assess the decontamination effec


MATERIALS AND METHODS


20 and 21 day-old Hybro broilers and 18 day-old Arbor Acress broilers, altogether 188 birds bred separately on the deep bedding were included in the observation of the toxic effect of aflatoxin B1. The microclimatic conditions corresponded to the requirements of the broiler chicken fattening during one fattening round. The feed mixture BR2 was supplemented with natural ground zeolite and thermically modified zeolite at the con-centration of 0.5 % in the loose form ad libitum, drinking water was provided ad libitum too. The health status of the chickens was observed weekly with the focus on weight gains. Blood was taken in order to determine the enzyme activities of the alkaline phosphatase (ALP), lactate dehydrogenase (LD). 6 broilers from each group were destroyed by decapitation aimed at pathological and anatomical examinations. The samples of liver and ileum were fixed in 4 % formalin solution and prepared for histological examination. The chickens were not sexed, the selection was done randomly.
Pure aflatoxin B1 manufactured by Sigma Chemical Co., U.S.A. was applied with a probe at 0.5 g.kg-1, 25 g.kg-1 depending on the age 3 times a week. 12 hours prior to the aflatoxin B1 application the chickens did not receive any feed.


RESULTS AND DISCUSSION


Macroscopic and microscopic lesions


Relatively low concentrations of aflatoxin B1 used in our experiment lead to the lowering of the broilers growth. In our case, low aflatoxin B1 levels that did not cause either the losses or depression of the broilers growth could negatively influence the physiological processes and predispose the broilers to stress and diseases.
The application of 0,5% PM and PT in the feed mixture without aflatoxin B1 did not influence adversely the health or the utility of broiler chickens neither it lowered the toxicity of aflatoxin B1 alone.
The pathological lesions after the experimental intoxication of broiler chickens by aflatoxin B1 have been demonstrated by the vacuolation of the liver cells (hepatocytes) and persisted also during the recovery phase in intoxicated broilers..
We observed slight lymphocytic infiltration and dilated bloodvessels.
Liver is considered to be the organ that is most affected with toxic effect of aflatoxin B1. The extent of described histological changes has been connected with the changes of the activities of the specific ALP and AST enzymes, that testifies to hepatotoxicity.
The residues of aflatoxin B1 in liver were not proved even after repeated RIA examinations, what testifies to the rapid metabolism of aflatoxin B1 in liver and to its elimination from the broiler organism.
The rate and the way of the aflatoxin B1 metabolism depends on the species and individual susceptibility, sex, age, character of the diet and on the quantity of received toxin.
When observing aflatoxin in organism after an intoxication with really low concentrations in the feed mixtures it is important to know that aflatoxin B1 does not accumulate in the organism and even its high levels are metabolized relatively very quickly. The degradation of aflatoxin B1 in the liver of chickens, ducks, and pigs takes 32.3 min.-1.37 hour; 49,8 s; and 1.57 hour, respectively. The tissues of contaminated animals may contain as much as 10 % of received dose.
When comparing the natural and thermically modified zeolite with the simultaneous application of aflatoxin B1, the concentration of 0.5% of natural zeolite was more effective. We have found out that they do not exert the same protective effect against aflatoxin B1. The significant interactive influence of two zeolites PT and PM and of aflatoxin B1 on the chickens weight gain has been manifested at the age of 4 and 5 weeks by the moderation of both the lowered growth and harmful effects.
These results are similar to those obtained by HARVEY (1993) who did not find out any significant or insignificant favourable effects on aflatoxin B1 at the efficiency of three clinoptilolitic substances.
SCHEIDELER (1993) who investigated the efficiency of aluminosilicates on the sorption of aflatoxin B1 in chickens has proved a beneficial effect of sorbents on the production activity and percentage of the liver lipids. From biochemical indices, the activity of total proteins and LD in broilers was significant at the age of 49 days with 0.5 % PM.
The described liver microscopical changes in liver in aflatoxicosis have been accompa-nied with the changes in a leucogram by lymphocytosis and by the disorders of the per-centage of monocytes and neutrophils at the age of 35 and 49 days.
The effects of mycotoxins and other xenobiotics in vivo depend first of all on the activities of enzyme systems which influence their decontamination. In some cases these bioconversions result in compounds, which are more toxic than the original substances. The degree of the biological effects depends on the balance between the rapidity of various pathways by which a toxin is metabolized, modified and lead to ineffective derivatives. The detoxication in liver takes place in microsomal fractions of hepatoytes. The metabolites of aflatoxins M1, Q1, P1, B2 arise as the products of hydroxylation. The different detoxication function of liver as well as the role of liver enzyme systems participate in the protection and detoxication.
After the last application of aflatoxin B1 there are no detectable residues in tissues as early as after four days.


CONCLUSION


Based on our results we assume that the binding between aflatoxin B1 and zeolite in the gastrointestinal tract really occurred with the lowering of the toxicity and improvement of production parameters.
Aflatoxin B1 induced an accumulaton of lipids in the liver and the vacuolation of hepatocytes. This increase may have two origins: general inhibition of lipid transport and interference in lipogenesis.