Effects of level and source of dietary selenium on maternal and fetal body weight, visceral organ mass, cellularity estimates, and jejunal vascularity in pregnant ewe lambs

¹ Center for Nutrition and Pregnancy, Animal and Range Sciences Department, North Dakota State University, Fargo 58105
² USDA-ARS, U.S. Sheep Experiment Station, Dubois, ID 83423

^* To whom correspondence should be addressed. E-mail: Joel.Caton{at}ndsu.edu.

	Abstract

Pregnant Targhee ewe lambs (n = 32; BW = 45.6 ± 2.2 kg) were allotted randomly to 1 of 4 treatments in a completely randomized design to examine effects of level and source of dietary Se on maternal and fetal visceral organ mass, cellularity estimates, and maternal jejunal crypt cell proliferation and vascularity. Diets contained (DM basis) either no added Se (CON) or supranutritional Se included in diets from high-Se wheat at 3.0 ppm Se (SW) or from sodium selenate at 3 (S3) or 15 (S15) ppm Se. Diets were similar in CP (15.5%) and ME (2.68 Mcal/kg of DM) and were fed to meet or exceed requirements. Treatments were initiated at 50 ± 5 d of gestation. The CON, SW, S3, and S15 treatment diets provided 2.5, 75, 75, and 375 µg Se/kg BW, respectively. On day 134 ± 10 of gestation, ewes were necropsied and tissues harvested. Contrasts, including CON vs. Se treatments (SW, S3, and S15), SW vs. S3, and S3 vs. S15, were used to evaluate differences among Se levels and sources. There were no differences in ewe initial and final BW. Full viscera and liver mass (g/kg empty BW and g/kg maternal BW) and maternal liver protein concentration (mg/g) and content (g) were greater (P < 0.04) in Se-treated compared with CON ewes. Maternal liver protein concentration was greater (P = 0.01) in SW vs. S3 ewes, and content was greater (P = 0.01) in S15 compared with S3 ewes. Maternal jejunal mucosal DNA concentration (mg/g) was greater (P = 0.08) in SW compared with S3 ewes. Total number of proliferating cells in maternal jejunal mucosa was greater (P = 0.02) in Se-fed compared with CON ewes. Capillary number density within maternal jejunal tissue was greater (P = 0.08) in S3 compared with SW ewes. Selenium treatment resulted in reduced fetal heart girth (P = 0.08). Fetal kidney RNA (P = 0.04) and protein concentrations (mg/g; s = 0.03) were greater in Se-treated compared with CON ewes. These results indicate that supranutritional dietary Se increases cell numbers in maternal jejunal mucosa through increased crypt cell proliferation. No indications of toxicity were observed in any of the Se treatments.

Key Words: cellularity, fetal, maternal, pregnancy, selenium, sheep

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