Experiment to determine limits of tolerance for fumonisin B1 in weaned piglets

In Hungary almost 70 % of mould-affected maize inspected since 1993 was fou nd to be contaminated with fumonisin B1 (FB1) (mean 2.6-8.65mg/kg; maximum 9.8-75.1mg/kg), the degree of this contamination was found to increase from year to year (Fazekas et al., 1997b). In this experiment, in order to defi ne tolerance limit values, the effect of exposing weaned piglets to FB1 in low doses over a 4-week period was examined. The experiment was performed w ith 20 weaned barrows of Danish Landrace breed. After a 5-day adaptation pe riod cultures of the fungus Fusarium moniliforme a ere mixed into the anima ls' feed in concentrations that resulted in a daily intake of fumonisin B1 of 0, 10, 20 and 40 mg/kg feed. Feeding with the toxin was observed to exer t no significant effect on body weight gain or feed consumption in the anim als, no clinical signs were observed and no mortality traceable to toxic ef fects occurred. In computer tomography examinations performed in the second and fourth weeks mild and more severe pulmonary oedema was diagnosed in th e experimental animals. The processes developing in the pulmonary parenchym a were corroborated by the mathematical and statistical evaluation procedur es applied. The haematological parameters examined revealed no change attri butable to toxic effects, while with respect to the biochemical parameters, an increase in aspartate aminotransferase (AST) activity dependent on dosa ge, indicating a pathological change in the liver, was ascertained in;in th ree experimental groups. The free sphinganine to sphingosine ratio (SA/SO), which is regarded as the most sensitive bioindicator of fumonisin toxicosi s, showed an increase proportionate to toxin concentration for all three do sages. Dissection revealed mild cases of pulmonary oedema in three of the a nimals given doses of 10 p.p.m. (n = 4), two mild and two severe cases in t hose exposed to 20p.p.m. (n = 5), and severe cases in all five animals give n 40p.p.m. The oedema of non-inflammatory origin was confirmed by histopath ological examinations. The findings of this experiment which indicate that in this study FB1 admin istered in substantially lower concentrations than those reported in the li terature resulted in severe pathological changes, point to the importance o f studies involving even lower doses.