EFFECT OF THE MYCOTOXINS, NIVALENOL AND ZEARALENONE, IN MAIZE NATURALLY INFECTED WITH FUSARIUM-GRAMINEARUM ON THE PERFORMANCE OF GROWING AND PREGNANT PIGS

Maize naturally infected with Fusarium graminearum and containing 11.5 mg nivalenol (NIV) kg(-1) and 3 mg zearalenone (ZEA) kg(-1) was fed to grower and pregnant pigs in five experiments. Inclusions of infected maize at 500 and 750 g kg(-1) in diets for grower pigs caused a deterioration of all performance traits in a 14 day experiment: voluntary feed intake (VFI) from 2.17 kg day(-1) (control) to 1.45 and 1.09 kg day(-1) average daily gain (ADG) from 0.79 kg day(-1) (control) to 0.50 and 0.45 kg day(-1) and feed conversion ratio (FCR) from 2.45 (control) to 3.49 and 3.23 respectively. In a paired-feeding experiment of 8 weeks duration, the VFI, ADG and FCR of grower pigs progressively worsened with increasing infected maize content. However, when pigs were fed a nutritionally similar control diet at intakes matched to those achieved by pigs given the mycotoxin-containing diets, their ADG and FCR were not significantly different (P > 0.05). The nutrient similarity of these diets was confirmed in an independent metabolism study measuring apparent digestibility and nitrogen retention. Feeding pigs with infected maize caused a marked and dose dependent depression (P < 0.05) in white cell and neutrophil counts. In two studies with sows, a comparison was made between a control diet and one containing 600 g kg(-1) infected maize when each diet was formulated to the same nutrient content and sows fed at 2 kg day(-1). In one study, diets were offered from when pregnancy was confirmed at 30 days post-mating until slaughter approximately 35 days later. In the second study, the diets were offered either from day of mating or from 30 day post-mating with all sows being slaughtered approximately 35 days later. In both studies, the infected maize diet had no adverse effect on the conception rate nor on the number and weight of foeti at slaughter compared to controls. In the second study, total white cell and lymphocyte counts were lower (P < 0.05) in sows fed the infected maize diet.