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

Department of Animal Sciences, North Dakota State University, Fargo, North Dakota, United States
Journal of Animal Science (Impact Factor: 2.11). 10/2007; 85(10):2721-33. DOI: 10.2527/jas.2006-785
Source: PubMed


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 1 of 4 treatments in a 2 x 2 factorial arrangement. Treatments were plane of nutrition [control, 100% of requirements vs. restricted, 60% of controls] and dietary Se [adequate Se, ASe (6 microg/kg of BW) vs. high Se, HSe (80 microg/kg of BW)] from Se-enriched yeast. Selenium treatments were initiated 21 d before breeding and dietary restriction began on d 64 of gestation. Diets contained 16% CP and 2.12 Mcal/kg of ME (DM basis) and differing amounts were fed to control and restricted groups. On d 135 +/- 5 (mean +/- range) of gestation, ewes were slaughtered and visceral tissues were harvested. There was a nutrition x Se interaction (P = 0.02) for maternal jejunal RNA:DNA; no other interactions were detected for maternal measurements. Maternal BW, stomach complex, small intestine, large intestine, liver, and kidney mass were less (P < or = 0.01) in restricted than control ewes. Lung mass (g/kg of empty BW) was greater (P = 0.09) in restricted than control ewes and for HSe compared with ASe ewes. Maternal jejunal protein content and protein:DNA were less (P < or = 0.002) in restricted than control ewes. Maternal jejunal DNA and RNA concentrations and total proliferating jejunal cells were not affected (P > or = 0.11) by treatment. Total jejunal and mucosal vascularity (mL) were less (P < or = 0.01) in restricted than control ewes. Fetuses from restricted ewes had less BW (P = 0.06), empty carcass weight (P = 0.06), crown-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 controls. Fetuses from HSe ewes had heavier (P < or = 0.09) BW, and empty carcass, heart, lung, spleen, total viscera, and large intestine weights compared with ASe ewes. Nutrient restriction resulted in less protein content (mg, P = 0.01) and protein:DNA (P = 0.06) in fetal jejunum. Fetal muscle DNA (nutrition by Se interaction, P = 0.04) concentration was greater (P < 0.05) in restricted ewes fed HSe compared with other treatments. Fetal muscle RNA concentration (P = 0.01) and heart RNA content (P = 0.04) were greater in HSe vs. ASe ewes. These data indicate that maternal dietary Se may alter fetal responses, as noted by greater fetal heart, lung, spleen, and BW.

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    • "The ethanol was allowed to evaporate overnight at room temperature in complete darkness before feeding (Lemley et al., 2012). The amount of feed offered to individual ewes was adjusted weekly based on BW and change in BW to ensure the desired average daily gains were achieved (Reed et al., 2007). Ewes were maintained on their given dietary treatments until 130 days of gestation. "
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    ABSTRACT: Primiparous ewes (n=32) were assigned to dietary treatments in a 2×2 factorial arrangement to determine effects of nutrient restriction and melatonin supplementation on maternal and fetal pancreatic weight, digestive enzyme activity, concentration of insulin-containing clusters and plasma insulin concentrations. Treatments consisted of nutrient intake with 60% (RES) or 100% (ADQ) of requirements and melatonin supplementation at 0 (CON) or 5 mg/day (MEL). Treatments began on day 50 of gestation and continued until day 130. On day 130, blood was collected under general anesthesia from the uterine artery, uterine vein, umbilical artery and umbilical vein for plasma insulin analysis. Ewes were then euthanized and the pancreas removed from the ewe and fetus, trimmed of mesentery and fat, weighed and snap-frozen until enzyme analysis. In addition, samples of pancreatic tissue were fixed in 10% formalin solution for histological examination including quantitative characterization of size and distribution of insulin-containing cell clusters. Nutrient restriction decreased (P⩽0.001) maternal pancreatic mass (g) and α-amylase activity (U/g, kU/pancreas, U/kg BW). Ewes supplemented with melatonin had increased pancreatic mass (P=0.03) and α-amylase content (kU/pancreas and U/kg BW). Melatonin supplementation decreased (P=0.002) maternal pancreatic insulin-positive tissue area (relative to section of tissue), and size of the largest insulin-containing cell cluster (P=0.04). Nutrient restriction decreased pancreatic insulin-positive tissue area (P=0.03) and percent of large (32 001 to 512 000 µm2) and giant (⩾512 001 µm2) insulin-containing cell clusters (P=0.04) in the fetus. Insulin concentrations in plasma from the uterine vein, umbilical artery and umbilical vein were greater (P⩽0.01) in animals receiving 100% requirements. When comparing ewes to fetuses, ewes had a greater percentage of medium insulin-containing cell clusters (2001 to 32 000 µm2) while fetuses had more (P<0.001) pancreatic insulin-positive area (relative to section of tissue) and a greater percent of small, large and giant insulin-containing cell clusters (P⩽0.02). Larger insulin-containing clusters were observed in fetuses (P<0.001) compared with ewes. In summary, the maternal pancreas responded to nutrient restriction by decreasing pancreatic weight and activity of digestive enzymes while melatonin supplementation increased α-amylase content. Nutrient restriction decreased the number of pancreatic insulin-containing clusters in fetuses while melatonin supplementation did not influence insulin concentration. This indicated using melatonin as a therapeutic agent to mitigate reduced pancreatic function in the fetus due to maternal nutrient restriction may not be beneficial.
    No preview · Article · Nov 2015 · animal
    • "Although diet type has previously affected organ masses in ruminants, this has often been confounded with DMI, nutrient intake, or both (Sainz and Bentley, 1997;McLeod and Baldwin, 2000;McCurdy et al., 2010). Because lambs fed the FOR diet had greater DMI than CONC-fed lambs, increased GIT masses of FOR-fed lambs may have been due to DMI (Rompala and Hoagland, 1987;Burrin et al., 1990;Reed et al., 2007) or dietary bulk (Rompala et al., 1988). In addition to fiber, protein intake was considerably greater for FOR-fed lambs, which may have also affected organ growth and final mass. "
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    ABSTRACT: We hypothesized that a portion of the individual differences observed for feed efficiency in ruminants can be attributed to gastrointestinal tract (GIT) size, which would vary based on diet type. The objective of this study was to determine GIT and visceral organ size in high and low efficiency growing lambs fed either a concentrate or forage-based diet. Growing wethers (n=82; 51.3±1.2 kg body weight [BW]) were fed a concentrate (CONC; 12.1% crude protein [CP], 17.6% neutral detergent fiber [NDF], 2.98 Mcal/kg metabolizable energy [ME]) or forage-based pelleted diet (FOR; 16.2% CP, 36.3% NDF, 2.31 Mcal/kg ME) for 49 d. Individual intake was measured with the GrowSafe System to determine residual feed intake (RFI). The 20% highest efficiency (low RFI, n=8) and 20% lowest efficiency (high RFI, n=8) lambs from each diet were slaughtered (66.6±2.3 kg BW; n=32 total), and the viscera was dissected and weighed. Data were analyzed as a 2×2 factorial with RFI class (high efficiency vs. low efficiency), diet type (FOR vs. CONC), and their interaction in the model. Organ masses were not affected (P>0.10) by the RFI class x diet type interaction. High efficiency lambs tended to have greater (P=0.09) pancreas and spleen actual mass than low efficiency lambs, although RFI class did not affect (P>0.15) other organ actual (g) or relative (g/kg BW) mass. Lambs fed FOR had greater (P≤0.01) actual and relative reticulum, omasum, large intestinal, and kidney mass and tended to have greater (P≤0.09) actual and relative small intestinal mass compared with lambs fed CONC. However, lambs fed CONC had greater (P≤0.05) actual rumen, heart, liver, and relative rumen mass than lambs fed FOR. All other visceral organ masses were unaffected (P>0.11) by diet type. Diet type, RFI class, and their interaction did not affect small intestinal length (P>0.10). Results of this study suggest that visceral organ size in growing lambs is more affected by diet type than individual feed efficiency. Based on this data, pancreas and spleen size may play a role in efficiency of feed utilization in lambs, however.
    No preview · Article · Apr 2015 · Livestock Science
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    • "(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) size, and RNA:DNA ratio used as an index of transcriptional activity (Reed et al., 2007). "
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    ABSTRACT: Previously we reported increased umbilical artery blood flow in ewes supplemented with melatonin from mid- to late-pregnancy, while maternal nutrient restriction decreased uterine artery blood flow. To further unravel these responses, this study was designed to assess placental cell proliferation and vascularity following supplementation with melatonin or maternal nutrient restriction. For the first experiment, 31 primiparous ewes were supplemented with 5mg of melatonin per day (MEL) or no melatonin (CON) and allocated to receive 100% (adequate fed; ADQ) or 60% (restricted; RES) of their nutrient requirements from day 50 to 130 of gestation. To examine melatonin receptor dependent effects, a second experiment was designed utilizing 14 primiparous ewes infused with vehicle, melatonin, or luzindole (melatonin receptor 1 and 2 antagonist) from day 62 to 90 of gestation. For experiment 1, caruncle concentrations of RNA were increased in MEL-RES compared to CON-RES. Caruncle capillary area density and average capillary cross-sectional area were decreased in MEL-RES compared to CON-RES. Cotyledon vascularity was not different across dietary treatments. For experiment 2, placental cellular proliferation and vascularity were not affected by infusion treatment. In summary, melatonin interacted with nutrient restriction to alter caruncle vascularity and RNA concentrations during late pregnancy. Although melatonin receptor antagonism alters feto-placental blood flow, these receptor dependent responses were not observed in placental vascularity. Moreover, placental vascularity measures do not fully explain the alterations in uteroplacental blood flow. Copyright © 2014 Elsevier B.V. All rights reserved.
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