The effects of zearalenone on reproduction in swine. II. The effect on puberty attainment and postweaning rebreeding performance.
Eighty-five prepuberal, crossbred gilts received, ad libitum, a diet containing 0 or 10 ppm purified zearalenone for 30 d beginning at 145 to 193 d of age. At the end of this period all gilts were placed on the control diet and exposed daily to a mature boar for 60 d. Within 3 to 5 d of zearalenone ingestion, gilts showed marked vulval swelling and reddening, which continued for the 30-d feeding period. Thereafter symptoms slowly subsided. Zearalenone treated gilts showed first estrus significantly later than controls (P<0.05), but the proportion of gilts showing estrus within 60 d of boar exposure was similar (P>0.05). The length of the first estrous cycle was not affected by the ingestion of zearalenone before puberty (P>0.05). In a second study, 65 multiparous, crossbred sows were full-fed twice daily a ration containing 0 or 10 ppm of purified zearalenone beginning 14 d before weaning. Postweaning, all sows were fed the control diet, were checked for estrus daily, and inseminated at the first postweaning estrus. Neither sows nor gilts from their litters exhibited signs of hyperestrogenism during treatment. Weaning to estrus interval was significantly extended in zearalenone treated sows (P<0.05), but all other variables of fertility assessed were similar. These data suggest that zearalenone ingestion before puberty delays the stimulation of puberty associated with boar exposure, but does not affect subsequent cyclicity if zearalenone is removed from the ration. Similarly, zearalenone ingestion during lactation delays the return to estrus after weaning, but does not affect subsequent fertility when removed from the ration at weaning.
Edwards
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S
Department of Animal Sciences, University of Missouri, Columbia, MO 65211, USA.
Cantley
T C
TC
Day
B N
BN