A Comparison of Effects of Zearalenone and Estradiol Benzoate on Reproductive Function during the Estrous Cycle in Gilts2

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Abstract
Effects of estradiol benzoate (EB) and zearalenone (Z) on luteal maintenance and plasma hormone concentrations were studied in 45 gilts. Gilts were allocated to receive either 20 mg Z, 2 mg EB or no treatment (C) on d 1 to 5 (T1), 6 to 10 (T2) or 11 to 15 (T3) of an estrous cycle (five per treatment). Onset of estrus was designated as d 0 of the estrous cycle. Zearalenone was added to the daily ration and EB was administered via an intramuscular injection. Blood samples were collected every 10 min over a 4-h period on the first 2 d prior to onset of treatment; the first, third and fifth days of treatment; and the first two and the fifth day after the end of the treatment periods. Gilts receiving EB and Z during T2 and T3 had longer (P<.05) inter-estrous intervals than C gilts. The range in inter-estrous intervals for Z and EB treatments was 28 to 74 and 27 to 63 d, respectively. Mean plasma progesterone concentrations were elevated (P<.05) during T2 and T3 in EB and Z-treated gilts when compared with C females. Estradiol benzoate treatment during T2 and T3 reduced (P<.05) mean plasma luteinizing hormone (LH) concentrations more than C or Z treatments. Mean plasma concentrations of 13, 14-dihydro-, 15-keto-prostaglandin F2α (PGFM) during T3 were higher (P<.05) in C and Z gilts on d 13 and 15 post-estrus when compared with EB gilts. These results indicated that 2 mg EB or 20 mg Z from d 6 to 10 or 11 to 15 of the estrous cycle extended the inter-estrous interval in swine. Estradiol benzoate during the same periods decreased mean plasma LH concentrations while Z did not. Additionally, EB treatment during T3 prevented the increase in PGFM concentrations of d 13 and 15 observed in both C and Z gilts. Copyright © 1987. American Society of Animal Science . Copyright 1987 by American Society of Animal Science