Abstract

Wheat naturally infected with Fusariurn graminearurn on a farm in south-eastern Queensland contained mean concentrations of 23 mg 4-deoxynivalenol (DON) kg-1 and 4 mg zearalenone (ZEA) kg-1. No other mycotoxins were detected. The wheat was incorporated into diets containing DON ranging from 0-14 mg kg-1 and corresponding ZEA concentrations. Diets were fed in two experiments to a total of 66 pigs of an improved synthetic breed (half each sex, initial liveweights about 27 kg). The first experiment lasted 14 days and tested short-term responses, while the second was a growth trial lasting up to 14 weeks. Pigs were fasted for 24 h before the diets were first offered. In the first experiment, the pigs ate readily for 10-15 min and thereafter sparingly or not at all for several hours. Vomiting commenced in pigs consuming the most DON after 10-20 min and continued for the next hour. A similiar pattern was seen in the growth trial. In total, vomiting was observed in 13 pigs on the first day of feeding, but not thereafter. Vomiting was accompanied by signs of abdominal distress and teeth grinding. This was followed by marked feed refusal, the extent being related linearly to increasing DON concentrations, so that pigs offered the most DON lost weight during the growth trial. Voluntary feed intake was depressed by about 6% for each 1 mg kg-1 of dietary DON, although some tolerance developed over time. Slight diarrhoea was noted in some pigs, and a few females showed oestrogenic effects due to the ZEA. The feed refusal was well correlated with that obtained by other workers using purified DON. Feed conversion was not adversely affected until DON concentrations exceeded about 8 mg kg-1.