Maternal selenium supplementation and timing of nutrient restriction in pregnant sheep: Effects on maternal endocrine status and placental characteristics1

Abstract

To determine the effects of maternal Se intake and plane of nutrition during midgestation, late gestation, or both on hormone and metabolite concentrations in the dam and on placental characteristics, pregnant ewe lambs (n = 64) were assigned to 1 of 8 treatments arranged in a 2 x 2 x 2 factorial array: Se level [initiated at breeding; adequate (3.05 microg/kg of BW) or high (70.4 microg/kg of BW)] and nutritional level [100% (control) or 60% (restricted) of NRC recommendations] fed at different times of gestation [d 50 to 90 (midgestation) or d 91 to 130 (late gestation)]. The control ewes had a greater (P = 0.01) percentage change in BW from d 50 than restricted ewes during both mid- and late gestation. Although blood urea N was not affected by either Se or nutritional level, restricted ewes had greater (P = 0.01) concentrations of circulating Se on d 66, 78, 106, 120, and 130 of gestation compared with control ewes. Both Se and timing of the nutritional level affected circulating progesterone; however, only nutritional level affected thyroxine and triiodothyronine concentrations in the dam. Nutrient restriction during late gestation decreased (P<or= 0.01) fetal BW and fetal fluid weight compared with the control ewes (3.75 vs. 4.13 +/- 0.10 kg and 1.61 vs. 2.11 +/- 0.11 kg). Although neither Se nor nutritional level affected (P >or= 0.1) placental, caruncular, or cotyledonary weights, cotyledonary cellular proliferation was decreased (P < 0.05) in ewes receiving a high concentration of Se compared with those receiving adequate Se. In addition, either Se or nutritional level affected vascular endothelial growth factor (VEGFA), VEGFA-receptor 1, VEGFA-receptor 2, and NO synthase mRNA abundance in the cotyledonary tissue. In the caruncular tissue, either Se or nutritional level affected VEGFA-receptor 1, placental growth factor, and NO synthase mRNA abundance. Selenium supplementation and the duration or timing of nutrient restriction appear to influence the endocrine and metabolic status of the ewe, which may influence nutrient transport and placental function.

Neonatal hormone changes and growth in lambs born to dams receiving differing nutritional intakes and selenium supplementation during gestation

“…Asymmetric IUGR has been documented in several mammalian species including sheep (Jensen et al 1999, Anthony et al 2003, Lang et al 2003, swine (Widdowson 1971, Bauer et al 1998, guinea pigs (Saintonge & Rosso 1981), and humans (Pearce & Campbell 1985). As we believe that our nutritional restriction model is due to differences in placental function, independent of size (Lekatz et al 2010(Lekatz et al , 2011, basing offspring organ mass data per unit brain (i.e. a denominator that is consistent regardless of maternal nutritional intake) may be advantageous.…”

“…Lamb serum samples were analyzed for cortisol concentration as described previously (Lekatz et al 2010). Briefly, serum samples (10 ml) were assayed in duplicate by the chemiluminescence immunoassay (Immulite 1000; Siemens, Los Angeles, CA, USA).…”

Nutritional plane and selenium supply during gestation affect yield and nutrient composition of colostrum and milk in primiparous ewes1

“…In this research model, nutritional plane during gestation has affected ewe endocrine profiles. Nutrient-restricted ewes had decreased IGF-I (Ward et al, 2008), progesterone Lekatz et al, 2010), and thyroid hormones (Ward et al, 2008;Lekatz et al, 2010), whereas ewes fed a high nutritional plane had decreased estradiol and progesterone but increased prolactin (Camacho et al, 2010) and cortisol during gestation. These alterations in hormones likely interact to play a role during the crucial mammary growth and development of gestation Banchero et al, 2006).…”

“…Maternal changes in body composition Carlson et al, 2009;Meyer et al, 2010b), endocrine and metabolic status (Ward et al, 2008;Lekatz et al, 2010), and colostrum yield and nutrient content (Swanson et al, 2008) have accompanied changes observed in offspring. Therefore, we hypothesized that gestational nutrition alters the subsequent milk production of the dam, even when nutrient requirements of lactation are met.…”

Maternal nutrition during pregnancy influences offspring wool production and wool follicle development1

“…This information is novel and the mechanism for this is unknown. Perhaps increased concentrations of circulating Se in the offspring reduced the cellular proliferation of the secondary follicles, which has been observed in other tissue types (Tapiero et al, 2003;Carlson et al, 2009;Lekatz et al, 2010).…”