Effects of selenium supply and dietary restriction on maternal and fetal body weight, visceral organ mass, cellularity estimates, and jejeunal vascularity in pregnant ewe lambs.

Authors: REED, JAKE; WARD, MARCY; VONNAHME, KIMBERLY; NEVILLE, TAMMI; JULIUS, S; BOROWICZ, P; Taylor, Joshua - Bret; REDMER, DALE; REYNOLD, LAWRENCE; CATON, JOEL

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2007
Publication Date: 7/8/2007
Citation: Reed, J.J., Ward, M.A., Vonnahme, K.A., Neville, T.L., Julius, S.L., Borowicz, P.P., Taylor, J.B., Redmer, D.A., Reynold, L.P., Caton, J.S. 2007. Effects of selenium supply and dietary restriction on maternal and fetal body weight, visceral organ mass, cellularity estimates, and jejeunal vascularity in pregnant ewe lambs.. Journal of Animal Science. doi:10.2527/jas.2006-785

Interpretive Summary: We investigated the effects of maternal nutrient restriction and supranutritional-dietary selenium, from a high selenomethionine source, on fetal growth. Restricting daily-nutrient intake of pregnant ewe lambs resulted in reduced body and organ growth of their fetuses. Feeding supranutritional selenium to pregnant ewe lambs seemed to result in heavier fetal-spleen, -heart, and -lung weights, but lighter fetal-adrenal weight. There is some (but limited) evidence that the supranutritional-selenium effects seemed to be altered when daily-nutrient intake of the pregnant ewe is restricted.

Technical Abstract: To examine effects of nutrient restriction and dietary Se on maternal and fetal visceral tissues, 36 pregnant Targhee-cross ewe lambs were allotted randomly to one of four treatments in a 2 x 2 factorial design. Factors were nutrition [control nutrition (CON, 100% of requirements) vs. restricted nutrition (RES, 60% of controls] and dietary Se [Adequate Se (ASe, 7.4 'g/kg BW) vs. High Se (HSe, 81.5 'g/kg BW]. Selenium treatments were initiated 21 d prior to breeding and restriction treatments on d 64 of gestation. Diets were 16% CP and 2.12 Mcal/kg metabolizable energy (DM basis). On d 135 ± 5 of gestation, ewes were slaughtered and tissues harvested. There was (P = 0.02) a nutrition x Se interaction for maternal jejunal RNA:DNA; there were no other interactions for maternal measurements. Maternal BW (P = 0.001), stomach complex (P = 0.001), small intestine (P = 0.001), large intestine (P = 0.001), liver (P = 0.001), and kidney (P = 0.01) mass were decreased in RES vs. CON ewes. Lung mass (g/kg empty BW) was greater (P = 0.09) in RES vs. CON ewes and for HSe compared with ASe ewes. Maternal jejunal protein content and protein:DNA were decreased (P = 0.001 and 0.002, respectively) in RES vs. CON ewes. Maternal jejunal DNA and RNA concentrations and total proliferating cells were not affected (P = 0.35, 0.11, and 0.34, respectively) by treatment. Total jejunal and mucosal vascularity (mL) decreased (P = 0.001 and 0.01) in RES vs. CON ewes. Fetuses from RES ewes had decreased BW (P = 0.06), empty carcass weight (P = 0.06) and decreased crown to rump length (P = 0.03), liver (P = 0.01), pancreas (P = 0.07), perirenal fat (P = 0.02), small intestine (P = 0.007), and spleen weights (P = 0.03) compared with fetuses from CON ewes. Fetuses from HSe ewes had heavier BW (P = 0.08), empty carcass (P = 0.09), heart (P = 0.09), lung (P = 0.06), spleen (P = 0.05) total viscera (P = 0.03), and large intestine (P = 0.01) weights compared with ASe ewes. Nutrient restriction resulted in decreased protein content (mg, P = 0.01) and protein:DNA (P = 0.06) in fetal jejunum. Protein concentrations (mg/g) decreased in fetal heart (P = 0.07) and muscle (P = 0.02) due to nutrient restriction. Fetal heart RNA content (P = 0.04) and muscle RNA concentration (P = 0.01) were greater in HSe vs. ASe ewes. These data indicated dietary Se may provide a sparing effect on the fetus when maternal nutrition is limiting.