|Taylor, Joshua - Bret|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2013
Publication Date: 6/1/2013
Citation: Meyer, A.M., Neville, T.L., Reed, J.J., Taylor, J.B., Reynolds, L.P., Redmer, D.A., Hammer, C.J., Caton, J.S. 2013. Maternal nutritional plane and selenium supply during gestation impacts visceral organ mass and intestinal growth and vascularity of neonatal lamb offspring. Journal of Animal Science. 91:2628-2639. 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 to pregnant ewes is safe for the fetus and neonatal offspring. Further, the results demonstrate the safety of supranutritional dietary selenium in pregnant ewes receiving limited and excessive total nutrition.
Technical Abstract: To investigate effects of nutritional plane and Se supply during gestation on neonatal offspring visceral organ mass and intestinal growth and vascularity, 84 primiparous Rambouillet ewes (age = 240 ± 17 d, BW = 52.1 ± 6.2 kg), were allocated to a 2 × 3 factorial design. Factors included Se [adequate Se (ASe, 11.5 µg/kg BW) or high Se (HSe, 77.0 µg/kg BW)] initiated at breeding and nutritional plane [60% (restricted; RES), 100% (control; CON), or 140% (high; HIH) of NRC requirements] initiated at d 40 of gestation. Ewes were fed and housed individually. At parturition, all lambs were removed and reared artificially until necropsy on d 20.6 ± 0.9 of age, when visceral organs were dissected and jejunal samples were collected. Lambs born to ewes fed CON and HIH had greater (P < 0.04) BW, gastrointestinal tract, stomach complex, and liver masses at necropsy than RES. Large intestinal and pancreatic masses, as well as stomach complex, large intestinal, and liver proportional masses, demonstrated (P = 0.08) a nutritional plane × Se supply interaction. Proportional pancreatic mass was greater (P = 0.03) for lambs born to RES ewes than HIH. Although small intestinal mass was not affected (P = 0.18) by gestational treatment, lambs born to HIH-fed ewes had greater (P = 0.09) jejunal DNA concentration than RES and CON and greater (P = 0.01) total DNA than RES. Nutritional plane and Se supply interacted to affect (P = 0.003) jejunal percent proliferation and total proliferating small intestinal cells, although jejunal crypt depth and villus length were not affected by gestational treatment (P = 0.17). Jejunal glucagon-like peptide-2 (GLP-2) mRNA expression was greater (P = 0.07) in lambs born to ewes fed RES compared with CON and HIH, although GLP-2 receptor was unaffected (P = 0.13). Jejunal capillary size was affected (P = 0.09) by the interaction of nutritional plane × Se supply. Additionally, lambs from CON ewes had greater (P = 0.04) jejunal capillary surface density than RES. Nutritional plane and Se supply interacted to affect (P = 0.07) jejunal soluble guanylate cyclase mRNA expression in a manner opposite of capillary size. In conclusion, neonatal lamb visceral organ masses were affected by gestational nutrition, even when lambs were fed for ad libitum intake and managed similarly postnatally. Despite similar small intestinal mass at d 20 of age, jejunal growth, vascularity and gene expression were altered by maternal nutrition during gestation.