Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides, a fungus that commonly contaminates maize. Sex-related effects of FB1 have been observed with respect to carcinogenicity in rodents, to performances in pigs and immunosuppression in mice. In the present study the sex-related effect of FB1 on the pig immune response was determined. Female and castrated male piglets received for 28d either control feed or feed contaminated with 8mg FB1/kgfeed in the form of F. verticillioidesculture material. At day 7 and day 21, animals were immunised subcutaneously with a Mycoplasma agalactiae vaccine. Ingestion of FB1-contaminated feed significantly decreased weight gain in males but had no effect in females. No sex-related difference was observed in biochemical parameters, but a higher level of creatinine was noted in toxin-treated animals. FB1 also altered the pig immune response in a sex-specific manner. In males, ingestion of FB1-contaminated feed significantly decreased specific antibody levels after vaccination as well as the mRNA expression level of IL-10. In females, the toxin has no effect on specific antibodies or on cytokine mRNA levels. The results of the present study indicatethat FB1 is immunosuppressive in pigs. The magnitude of this FB1-induced immunosuppression is highly dependent on sex, with males being more susceptible than females.

Chemical compounds that mimic or block some of the actions of the steroid hormone oestradiol, have created public concern primarily because of potential adverse reproductive effects in wildlife and humans. Many studies, in vivo and in vitro, have revealed abnormal reproductive function following exposure to these compounds. The number of chemicals known to have the potential to modulate endocrine functions is increasing. In contrast to humans and wildlife, the potential reproductive effects of exposure of domestic animals to endocrine disrupting compounds (EDC) have been studied little. The aim of this overview is to evaluate the possible contribution of EDC to reproductive failure in domestic ruminants.

Sources and classes of EDC are discussed as well as their structure and the modes of hormone disruption. Endocrine disrupting agents may interfere with the reproductive processes of both males and females at several points of the reproductive cycle and through a range of physiological mechanisms. Extrapolating from the results obtained with laboratory animals, the mechanisms whereby infertility in domestic ruminants might be expressed by exposure to EDC through contaminated food and drinking water are addressed.

A preliminary risk assessment is included and it is concluded that under certain circumstances there may be a significantly enhanced intake of oestrogenic hormones and EDC through sewage-contaminated water or soil-contaminated herbage. The physiological consequences for domestic ruminants of EDC ingestion, at the rates estimated, are largely unknown. However, the levels of exposure to oestrogenic hormones and phthalates in grazing ruminants are such that when studying fertility problems in high-yielding dairy cattle the impacts of exposure to endocrine disruptors via the food and drinking water cannot be neglected.

Two experiments were made. In experiment 1, dairy cows in early lactation (2 to 4 weeks) and dairy cows in late lactation (34 to 36 weeks) were given aflatoxin B, (AFBt)at a level of 34 to 39 fig/day by feeding them contaminated compound food. The aflatoxin Mrcontent(AFMj) of raw milk was determined four times during the experimental period of 14 days. The milk yield was measured daily.

The carry-over rate of aflatoxin was proportionately 0·062 and 0·018 for cows in early and late lactation respectively. This difference was not only due to milk production level but possibly also associated to AFB, liver metabolism.

In experiment 2, eight high (40 kg milk per day) and eight low (16 kg milk per day) milk yielding cows, carry-over of AFB1 from compound food into AFM, in milk was measured at different levels ofAFB7 intake ranging from 7 to 57 fig/day. Independent of AFBj-intake, high-producing dairy cows had a higher carry-over rate than low producing animals (proportionately 0·038 v. 0·025). Carry-over ofAFB1 to AFM, was linearly correlated with milk yield. Variations in the level of AFM1 in milk of individual cows were not due to variations in milk yield. The relationship between AFB2 intake per day and AFM^content in milk per kg could be described by the formula: AFMj (ng/kg milk) = 119 AFB, intake (fig per cow per day) + 1·9. This means that in order to produce milk with less than 0·05 fig AFM, per kg milk the average daily individual intake in a herd should be limited to 40 fig AFB7 per day.

As dairy cows in their early to mid lactation period consume large quantities of compound food, a maximum level of AFB3 in dairy foods has to be set at an acceptable daily intake (ADI) value to guarantee that AFM1 levels in milk do not exceed tolerable levels.