|Taylor, Joshua - Bret|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2009
Publication Date: 6/1/2010
Citation: Meyer, A.M., Reed, J.J., Neville, T.L., Taylor, J.B., Hammer, C.J., Reynolds, L.P., Redmer, D.A., Vonnahme, K.A., Caton, J.S. 2010. Effects of nutritional plane and selenium supply during gestation on ewe and neonatal offspring performance, body composition, and serum selenium.. Journal of Animal Science. 88:1786-1800. Interpretive Summary: Rangelands in the Western United States can be challenging to utilize for livestock production. For example, some areas of the Intermountain West are deficient in the mineral selenium. Furthermore, forage growth on western ranges can be minimal during drought, which results in limited or insufficient nutrition for grazing animals, especially pregnant animals. Because these ranges are extensive, remote, and rugged, providing supplemental nutrition to grazing livestock is often prohibitive or very costly. Scientists at the USSES and North Dakota State University, Fargo have considered these production challenges extensively. Using a creative experimental approach, they studied how limited nutrition and high levels of dietary selenium during pregnancy affect growth of adolescent ewe and their lambs. Restriction of dietary energy and protein during pregnancy resulted in adolescent ewes giving birth to lambs with low body weights. When proper postnatal nutrition was provided to these lambs, postnatal growth rates were still lower than those of lambs born to ewes that were fed adequate energy and protein during pregnancy. By adding supranutritional selenium, in the form of natural selenium-rich wheat milling coproduct, to energy and protein deficient diets fed to pregnant adolescent ewes, ewe gains and body composition were better than similar treated ewes that were only fed adequate selenium.
Technical Abstract: To investigate effects of nutritional plane and Se supply during gestation on ewe and offspring performance and body composition, 84 Rambouillet ewe lambs (age = 240 ± 17 d, BW = 52.1 ± 6.2 kg), were allocated to a 2 x 3 x 2 factorial design. Factors included adequate (ASe) vs. supranutritional (HSe) dietary Se initiated at breeding; 60 (LOW), 100 (CON), or 140% (HIGH) of NRC requirements initiated at d 40 of gestation; and physiological stage at necropsy, immediately (PART) or 20 d (LACT) after parturition. At parturition, lambs were removed and artificially reared until necropsy on d 20.6 ± 0.9 of age. Ewes assigned to LACT were transitioned to a common diet meeting lactation requirements and mechanically milked once daily. From d 95 of gestation through parturition and to d 20 of lactation, ewe BW and BCS were least (P = 0.01) in RES, intermediate in CON, and greatest in HIGH ewes. Ewes fed HSe had greater (P = 0.05) BCS change than ASe during mid and late gestation. During gestation, HIGH ewes had the greatest (P < 0.001) ADG and G:F, with CON ewes intermediate and RES ewes least. During mid-gestation, HSe ewes had greater (P < 0.001) ADG and G:F than ASe ewes. Ewe backfat (BF) and LM area on d 135 of gestation were least (P < 0.001) in RES, intermediate in CON, and greatest in HIGH, with HSe ewes having greater (P = 0.03) BF than ASe ewes. During the first 20 d of lactation, ewes fed the RES had greater (P < 0.09) G:F than CON and HIGH. Physiological stage had no effect on ewe omental and mesenteric fat or perirenal fat weights, although both were greater (P < 0.001) in HIGH ewes than RES and CON. At birth, lambs born to RES ewes weighed less and had decreased curved crown rump length (P = 0.08) compared with CON and HIGH, and lambs from ASe-RES ewes were lighter (P < 0.08) than HSe-RES, ASe-CON, and ASe-HIGH. Lambs from RES dams had lower (P < 0.05) BW from d 7 to 19 and decreased (P < 0.07) overall ADG compared with CON and HIGH. Additionally, RES lambs had less (P = 0.08) perirenal fat than their counterparts and HIGH lambs had greater (P = 0.01) omental and mesenteric fat than RES. Results indicated that maternal nutrient restriction during gestation not only negatively affects the dam, but also results in antiproductive consequences for the fetus, which seem to persist after birth even when proper postnatal nutrition is provided. Some of these negative effects seemed to be reversed when supranutritional Se was fed to gestation ewes.