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Effect of ovarian regression and molt on plasma concentrations of thymosin beta 4 in domestic hens (Gallus domesticus). |
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| Authors: | R W Dickerman T H Wise and J M Bahr |
| Institution: | * Department of Physiology and Biophysics University of Illinois, Urbana, IL 61801, USA ** U.S.D.A., Agricultural Research Service Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933, USA *** Department of Animal Sciences University of Illinois, Urbana, IL 61801, USA |
| Abstract: | Molt induced by infusion of a gonadotropin-releasing hormone agonist (GnRH-A, (D-leu6, Pro9]-GnRH N-ethylamide]) or feed withdrawal (FW) has been used as a model to study interactions between ovarian activity and thymosin β4 during molting in domestic hens. Thirty-three laying hens were divided into three groups: 1, controls, 2, GnRH-A infusion induced molt (GnRH-A), or 3, FW induced molt. All groups had reduced daylength. Blood was sampled weekly and assayed for concentrations of thymosin β4 and progesterone (P4). Plasma P4 concentrations were significantly depressed in both treatment groups compared to controls, indicating ovarian regression. Plasma P4 concentrations had returned to control values in the GnRH-A group by 28 d after the start of treatment, while P4 was still depressed in the FW group at day 42 when the experiment ended. Plasma concentrations of thymosinβ4 were elevated relative to controls from day 7 through day 14 in the GnRH-A group and from day 7 until day 28 in the FW group. It is concluded that plasma concentrations of thymosin β4 are elevated during molting in domestic hens, but the elevation is not attributable to depressed P4 concentrations. |
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