THE REPRODUCTIVE EFFICIENCY OF GILTS FED VERY LOW LEVELS OF ZEARALENONE

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Abstract
In the first of three experiments, 60 prepuberal gilts (12–13 wk old) were fed diets containing 0.01 (control), 0.16, 0.36, 0.47, 1.28 and 2.21 mg zearalenone (ZEN) kg−1 feed for 63 d. Vulvovaginitis occurred in some gilts fed the control diet; there was a trend (P < 0.01) towards heavier uteruses as the dietary level of ZEN increased. Experiment 2 involved 16 gilts allocated in pairs in noncontiguous pens and fed diets containing 0.01 and 2.21 mg ZEN kg−1 feed for 42 d. No control gilt exhibited vulvovaginitis when separated from a treated gilt by an unoccupied pen while all eight of the treated gilts showed vulvovaginitis. Results suggested that estrogenic metabolites in the urine of gilts eating ZEN-contaminated feed might, if ingested, induce vulvovaginitis in other untreated gilts. Experiment 3 involved 40 gilts and four diets (0.01, 0.36, 0.47 and 1.28 mg ZEN kg−1 feed). The gilts were bred and were necropsied between days 52 and 55 of pregnancy. The incidence of vulvovaginitis differed (P < 0.01) among diets, tending to increase with higher ZEN levels. Fewer gilts fed the two higher levels of ZEN could be bred than those fed the lower ZEN levels. Serum progesterone concentrations ranged from 0.1 to 0.6 ng mL−1 for prepubertal gilts, and from 22 to 29 ng mL−1 during early pregnancy. Fetal mortality, while not significantly different, was numerically less for the control gilts than for those fed the ZEN-treated diets. Feed intake and weight gain were not affected significantly, by the inclusion of zearalenone in any of the experiments. The data indicated that zearalenone did not have serious effects on the reproductive efficiency of young gilts at levels below 0.5 mg kg−1 feed. Key words: Zearalenone, gilt, reproduction, estrus, fetus