|MEYER, ALLISON - North Dakota State University|
|REED, JAKE - North Dakota State University|
|NEVILLE, TAMMI - North Dakota State University|
|Taylor, Joshua - Bret|
|REYNOLD, LAWRENCE - North Dakota State University|
|REDMER, DALE - North Dakota State University|
|VONNAHME, KIMBERLY - North Dakota State University|
|CATON, JOEL - North Dakota State University|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2012
Publication Date: 8/1/2012
Citation: Meyer, A.M., Reed, J., Neville, T.L., Taylor, J.B., Reynold, L.P., Redmer, D.A., Vonnahme, K.A., Caton, J.S. 2012. Effects of nutritional plane and selenium supply during gestation on visceral organ mass and indices of intestinal growth and vascularity in primiparous ewes at parturition and during early lactation. Journal of Animal Science. 90:2733-2749.
Interpretive Summary: Recently, we have demonstrated the advantages of feeding diets naturally rich in selenium to ruminant livestock. Critics have expressed concern about the potential for selenium toxicity at the dietary levels of selenium that we have proposed in the past. These results clearly demonstrate that selenium, from natural selenium-rich feeds, fed at 10-fold the recommended requirement is safe and nutritious for pregnant and lactating ewes. Further, the results demonstrate the safety of supranutritional dietary selenium in pregnant ewes receiving limited and excessive total nutrition.
Technical Abstract: Objectives were to investigate effects of nutritional plane and Se supply during gestation on visceral organ mass and intestinal growth and vascularization in ewes at parturition and during early lactation. Primiparous Rambouillet ewes (n = 84) were allocated to 2 × 3 × 2 factorial arrangement of treatments. Factors included dietary Se (adequate Se [ASe, 11.5 Ig/kg BW] or high Se [HSe, 77.0 Ig/kg BW]), nutritional plane (60% [restricted; RES], 100% [control; CON], or 140% [high; HIH]), and physiological stage at necropsy (parturition or d 20 of lactation). At parturition, lambs were removed and 42 ewes (7 per treatment) were necropsied. Remaining ewes were transitioned to a common diet, which met lactation requirements, and mechanically milked for 20 d. In the absence of interactions (P > 0.10), main effects are reported. At parturition, stomach complex and liver masses were greatest for HIH, intermediate for CON, and least for RES (P < 0.02). Small intestinal mass was greater (P = 0.002) for HIH than RES and CON and greater (P < 0.01) for ASe than HSe. During early lactation, RES and CON gastrointestinal masses increased disproportionally to BW (P < 0.05). At parturition, jejunal mucosal density was less (P = 0.01) for RES than CON and HIH, whereas CON had greater (P < 0.003) jejunal mucosal RNA concentration and RNA:DNA than RES and HIH. Although there were no differences (P > 0.17) at parturition, jejunal cell percent proliferation was greatest in RES, intermediate in CON, and least in HIH (P = 0.09) at d 20 lactation. At both stages, RES had less (P = 0.01) jejunal capillary area density than HIH and less (P = 0.03) capillary surface density than CON and HIH. During lactation, jejunal capillary size was greater (P = 0.04) for ewes previously fed HSe compared with ASe. At parturition, ASe-HIH had greater (P < 0.02) jejunal mucosal endothelial nitric oxide synthase 3 (NOS3) mRNA than all other treatments and greater (P = 0.10) vascular endothelial growth factor (VEGF) than all treatments except ASe-RES. In addition, CON had less (P = 0.08) jejunal VEGF receptor-1 (FLT1) mRNA compared with RES and HIH, and ASe had greater (P = 0.003) FLT1 than HSe 51 at parturition. Ewes fed HIH had greater (P = 0.04) jejunal VEGF receptor-2 (KDR) mRNA compared with RES. Results indicate that maternal intestinal growth and vascularization are responsive to nutritional plane and dietary Se during gestation and undergo changes postpartum when under similar lactational management.