Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2012
Publication Date: 6/1/2012
Publication URL: http://handle.nal.usda.gov/10113/57619
Citation: Oliver, W.T., Miles, J.R., Diaz, D.E., Dibner, J.J., Rottinghaus, G.E., Harrell, R.J. 2012. Zearalenone enhances reproductive tract development, but does not alter skeletal muscle signaling in prepubertal gilts. Animal Feed Science And Technology. 174(1-2):79-85. Interpretive Summary: Mycotoxins are produced from molds in feedstuffs and can have dramatic effects, including reduced animal performance. Of particular note in swine is the mycotoxin zearalenone, which is known to decrease the reproductive performance of pigs, and gilts are particularly sensitive to the toxin. In addition, zearalenone down-regulates proteins associated with protein synthesis and cellular proliferation in cell culture systems. Determining the effects and mechanism of action of zearalenone on prepubertal gilts will improve our understanding of mycotoxins in swine feed, and will provide a rational basis for the development of new approaches to attenuate the effects of zearalenone on swine performance. Research conducted at the U.S. Meat Animal Research Center determined that feeding zearalenone contaminated feed to gilts resulted in a 50% increase in size of the reproductive tract, which is associated with an increase in a relatively low-abundance form of the estrogen receptor. No differences in growth performance were observed, and, contrary to published cell culture results, gilts did not have altered cellular signaling for protein synthesis or cell growth. These findings improve our understanding of the effect of zearalenone on pig performance and will aid in the development of approaches to alleviate the effect of mycotoxin contaminated feedstuffs in swine.
Technical Abstract: Zearalenone is a potent mycotoxin that has estrogenic properties. In vitro results indicate that zearalenone metabolites are capable of down-regulating proteins associated with protein synthesis (protein kinase B, Akt) and cellular proliferation (extracellular signal-regulated kinase, ERK) in muscle. The objectives of this study were to determine the effect of zearalenone consumption by prepubertal gilts on 1) growth performance and signaling for protein synthesis, and 2) reproductive tract development. Gilts (n = 10) were weaned at 21 d of age and allowed to adjust for 1 wk on a commercial diet. After 1 wk (d0), gilts were randomly assigned to consume a commercial basal diet (C) or C+1.5 mg/kg zearalenone for 4 wk, at which time gilts were euthanized, urine collected, and tissue collected and frozen. Zearalenone, alpha-zearalenol, and beta-zearalenol were detected at levels of less than 4 µg/kg in urine of C gilts, but were increased (292 ± 76, 113 ± 20, and 15 ± 3 µg/kg, respectively) in pigs consuming zearalenone (P < 0.01). No differences were observed in ADG, ADFI, or G:F between treatments (P > 0.28). Reproductive tract size was increased 2.4-fold (20.9 ± 4.3 vs. 50.6 ± 3.8 g) in zearalenone fed gilts (P < 0.01). Uterine endometrial gland development was increased 50% in gilts consuming zearalenone (P < 0.01). In uterus, estrogen receptor (ER)-alpha mRNA and protein were unchanged (P > 0.28), but gilts consuming zearalenone had 2.0- and 3.5-fold higher abundance of ER-beta mRNA and protein, respectively, compared to the C group (P < 0.01). No differences were observed in Akt, mammalian target of rapamycin (mTOR), or ERK protein phosphorylation or total abundance in skeletal muscle (P > 0.36) by feeding zearalenone. The consumption of zearalenone had no effect on growth performance or skeletal muscle signaling in prepubertal gilts, but zearalenone increased reproductive tract size and glandular development, possibly due, in part, to altering the expression of ER-beta.