title: Effects of selenium supply and dietary restriction on maternal and fetal metabolic hormones in pregnant ewe lambs.
abstract: The objective of these studies was to evaluate the effects of dietary restriction and Se on maternal and fetal metabolic hormones. In Exp. 1, pregnant ewe lambs (n = 32; BW = 45.6 +/- 2.3 kg) were allotted randomly to 1 of 4 treatments. Diets contained (DM basis) either no added Se (control), or supranutritional Se added as high-Se wheat at 3.0 mg/kg (Se-wheat), or sodium selenate at 3 (Se3) and 15 (Se15) mg/kg of Se. Diets (DM basis) were similar in CP (15.5%) and ME (2.68 Mcal/kg). Treatments were initiated at 50 +/- 5 d of gestation. The control, Se-wheat, Se3, and Se15 treatments provided 2.5, 75, 75, and 375 microg/kg of BW of Se, respectively. Ewe jugular blood samples were collected at 50, 64, 78, 92, 106, 120, and 134 d of gestation. Fetal serum samples were collected at necropsy on d 134. In Exp. 2, pregnant ewe lambs (n = 36; BW 53.8 +/- 1.3 kg) were allotted randomly to treatments in a 2 x 2 factorial arrangement. Factors were nutrition (control, 100% of requirements vs. restricted nutrition, 60% of control) and dietary Se (adequate Se, 6 microg/kg of BW vs. high Se, 80 microg/kg of BW). Selenium treatments were initiated 21 d before breeding, and nutritional treatments were initiated on d 64 of gestation. Diets were 16% CP and 2.12 Mcal/kg of ME (DM basis). Blood samples were collected from the ewes at 62, 76, 90, 104, 118, 132, and 135 d of gestation. Fetal blood was collected at necropsy on d 135. In Exp.1, dietary Se source and concentration had no effect (P > 0.17) on maternal and fetal serum IGF-I, triiodothyronine (T(3)), or thyroxine (T(4)) concentrations. Selenium supplementation increased (P = 0.06) the T(4):T(3) ratio vs. controls. In Exp. 2, dietary Se had no impact (P > 0.33) on main effect means for maternal and fetal serum IGF-I, T(3), or T(4) concentrations from d 62 to 132; however, at d 135, high-Se ewes had lower (P = 0.01) serum T(4) concentrations than adequate-Se ewes. A nutrition by Se interaction (P = 0.06) was detected for the T(4):T(3) ratios; ewes fed restricted and adequate-Se diets had greater (P = 0.10) T(4):T(3) ratios compared with the other treatments. Nutrient-restricted ewes had lower (P < 0.05) serum IGF-I, T(3), and T(4) concentrations. Fetal serum IGF-I concentrations were lower (P = 0.01) in restricted-vs. control-fed ewes; however, fetal T(3) and T(4) concentrations were unaffected (P > 0.13) by dietary Se or maternal plane of nutrition. These data indicate that dietary Se may alter maternal T(4):T(3) ratios. In addition, nutrient restriction during gestation reduces maternal IGF-I, T(3), and T(4) and fetal IGF-I concentrations.
authors.affiliation: Center for Nutrition and Pregnancy and Animal and Range Sciences Department, North Dakota State University, Fargo 58105, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Ward
authors.forename: T L
authors.initials: TL
authors.lastname: Neville
authors.forename: J J
authors.initials: JJ
authors.lastname: Reed
authors.forename: J B
authors.initials: JB
authors.lastname: Taylor
authors.forename: D M
authors.initials: DM
authors.lastname: Hallford
authors.forename: S A
authors.initials: SA
authors.lastname: Soto-Navarro
authors.forename: K A
authors.initials: KA
authors.lastname: Vonnahme
authors.forename: D A
authors.initials: DA
authors.lastname: Redmer
authors.forename: L P
authors.initials: LP
authors.lastname: Reynolds
authors.forename: J S
authors.initials: JS
authors.lastname: Caton
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004038:Diet, Reducing; D004305:Dose-Response Relationship, Drug; D005260:Female; D005333:Fetus; D005865:Gestational Age; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D039382:Maternal Nutritional Physiological Phenomena; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D011897:Random Allocation; D012643:Selenium / Q000008:administration & dosage*; D012756:Sheep / Q000097:blood / Q000502:physiology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D012643:Selenium; D013974:Thyroxine