Nutritionally induced tanycytic plasticity in the hypothalamus of adult ewes.

The blood-brain barrier regulates the transport of molecules that convey global energetic status to the feeding circuitry within the hypothalamus. Capillaries within the median eminence (ME) and tight junctions between tanycytes lining the third ventricle (3V) are critical components of this barrier. Herein, we tested the hypothesis that altering the plane of nutrition results in the structural reorganization of tanycytes, tight junctions, and capillary structure within the medial basal hypothalamus. Proopiomelanocortin (POMC) neuronal content within the arcuate nucleus of the hypothalamus (ARC) was also assessed to test whether reduced nutritional status improved access of nutrients to the ARC, while decreasing the access of nutrients of overfed animals. Multiparous, nongestating ewes were stratified by weight and randomly assigned to dietary treatments offered for 75 d: 200% of dietary recommendations (overfed), 100% of dietary recommendations (control), or 60% of dietary recommendations (underfed). The number of POMC-expressing neurons within the ARC was increased (P ≤ 0.002) in underfed ewes. Overfeeding increased (P ≤ 0.01) tanycyte cellular process penetration and density compared with control and underfeeding as assessed using vimentin immunostaining. Immunostaining of tight junctions along the wall of the 3V did not differ (P = 0.32) between treatments. No differences were observed in capillary density (P = 0.21) or classification (P ≥ 0.47) within the ME. These results implicate that changes within the satiety center and morphology of tanycytes within the ARC occur as an adaptation to nutrient availability.

Follicle-stimulating hormone receptors expression in ovine corpora lutea during luteal phase: effect of nutritional plane and follicle-stimulating hormone treatment.

Corpus luteum (CL), a transient endocrine gland critical for reproductive cyclicity and pregnancy maintenance, is controlled by numerous regulatory factors. Although LH is widely recognized as the major regulator, other factors may also affect luteal functions. It has been demonstrated that FSH receptors (FSHR) are expressed not only in ovarian follicles but also in other tissues within the reproductive tract, including the CL. To evaluate FSHR expression in nontreated (nonsuperovulated; experiment 1) or FSH-treated (superovulated; experiment 2) sheep fed a control (C; maintenance), excess (O; 2 × C), or restricted (U; 0.6 × C) diet, CL were collected at the early, mid and/or late luteal phases (n = 5-7 per group). Protein and messenger RNA (mRNA) expression of FSHR were detected in the CL from all groups using immunohistochemistry followed by image analysis and quantitative RT-PCR, respectively. Follicle-stimulating hormone receptor was immunolocalized to steroidogenic small and large and nonsteroidogenic luteal cells. In both experiments, FSHR protein expression was not affected by stage of luteal development or diet. In experiment 1, expression of mRNA for all FSHR variants was greater (P <0.02 to 0.0003) at the late phase than mid or early luteal phase, and in experiment 2, it was greater (P < 0.001) at the mid than early luteal phase. Plane of nutrition did not affect FSHR mRNA expression. Comparison of FSH-treated with nontreated ewes demonstrated that FSH increased FSHR protein expression by 1.5- to 2-fold (P < 0.0001) in all groups, and mRNA expression by 7- to 30-fold (P < 0.001) for (1) FSHR-1 in all groups except U at the early luteal phase, (2) FSHR-2 in C, O, and U at the mid-phase, but not early luteal phase, and (3) FSHR-3 in U at the mid-luteal phase. Our data demonstrate that (1) FSHRs are expressed in ovine CL at several stages of luteal development, (2) FSHR protein expression does not change during the luteal phase and is not affected by diet, (3) FSHR mRNA expression not only depends on the stage of the estrous cycle but also not affected by diet in nonsuperovulated or superovulated ewes, and (4) in vivo FSH treatment enhanced FSHR protein and/or mRNA expression in the CL depending on diet and phase of the estrous cycle. Presence of FSHR in the CL indicates a regulatory role of FSH in luteal function in sheep. As very little is known about the possible role of FSH and FSHR in luteal functions, further studies should be undertaken to elucidate the endocrine, molecular, and cellular mechanisms of FSH effects on the CL.

The impact of diet and arginine supplementation on pancreatic mass, digestive enzyme activity, and insulin-containing cell cluster morphology during the estrous cycle in sheep.

To determine the effect of feed intake and arginine treatment during different stages of the estrous cycle on pancreatic mass, digestive enzyme activity, and histological measurements, ewes (n = 120) were randomly allocated to 1 of 3 dietary groups; control (CON; 2.14-Mcal metabolizable energy/kg), underfed (UF; 0.6 × CON), or overfed (OF; 2 × CON) over 2 yr. Estrus was synchronized using a controlled internal drug release device for 14 d. At controlled internal drug release withdrawal, ewes from each dietary group were assigned to 1 of 2 treatments; Arg (L-Arg HCl, 155-µmol/kg BW) or Sal (approximately 10-mL saline). Treatments were administered 3 times daily via jugular catheter and continued until slaughter on d (day) 5 and 10 of the second estrus cycle (early luteal phase, n = 41 and mid-luteal phase, n = 39; yr 1) and d 15 of the first estrus cycle (late luteal phase, n = 40; yr 2). A blood sample collected from jugular catheters for serum insulin analysis before slaughter. The pancreas was then removed, trimmed of mesentery and fat, weighed, and a sample snap-frozen until enzyme analysis. Additional pancreatic samples were fixed in 10% formalin solution for histological examination of size and distribution of insulin-containing cell clusters. Data were analyzed as a completely randomized design with a factorial arrangement of treatments. Diet, treatment, and diet × treatment were blocked by yr and included in the model with initial BW used as a covariate. Day of the estrous cycle was initially included in the model but later removed as no effects (P > 0.10) were observed for any pancreatic variables tested. Overfed ewes had the greatest (P < 0.001) change in BW, final BW, change in BCS, and final BCS. A diet × treatment interaction was observed for change in BW and final BW (P ≤ 0.004). Overfed and CON had increased (P < 0.001) pancreas weight (g) compared with UF ewes. Protein concentration (g/pancreas) was the lowest (P < 0.001) in UF ewes, whereas protein content (mg/kg BW) was greater (P = 0.03) in UF than OF ewes. Activity of α-amylase (U/g, kU/pancreas, U/kg of BW, and U/g protein) and trypsin (U/pancreas) was greater (P ≤ 0.003) in OF than UF ewes. Serum insulin was the greatest (P < 0.001) in OF ewes. No effects were observed for pancreatic insulin-containing cell clusters. This study demonstrated that plane of nutrition affected several measurements of pancreatic function; however, the dosage of Arg used did not influence pancreatic function.

Dietary selenium and nutritional plane alter specific aspects of maternal endocrine status during pregnancy and lactation.

Objectives were to examine effects of selenium (Se) supply and maternal nutritional plane during gestation on placental size at term and maternal endocrine profiles throughout gestation and early lactation. Ewe lambs (n = 84) were allocated to treatments that included Se supply of adequate Se (ASe; 11.5 µg/kg BW) or high Se (HSe; 77 µg/kg BW) initiated at breeding and nutritional plane of 60% (RES), 100% (CON), or 140% (EXC) of requirements beginning on day 40 of gestation. At parturition, lambs were removed from their dams, and ewes were transitioned to a common diet that met requirements of lactation. Blood samples were taken from a subset of ewes (n = 42) throughout gestation, during parturition, and throughout lactation to determine hormone concentrations. Cotyledon number was reduced (P = 0.03) in RES and EXC ewes compared with CON ewes. Placental delivery time tended (P = 0.08) to be shorter in HSe ewes than in ASe ewes, whereas placental delivery time was longer (P = 0.02) in RES ewes than in CON and EXC ewes. During gestation, maternal progesterone, estradiol-17ß, and GH were increased (P < 0.05) in RES ewes and decreased (P < 0.05) in EXC ewes compared with CON ewes. In contrast, maternal cortisol, IGF-I, prolactin, triiodothyronine, and thyroxine were decreased in RES ewes and increased in EXC ewes compared with CON ewes during gestation. Selenium supply did not alter maternal hormone profiles during gestation. During parturition and lactation, maternal hormone concentrations were influenced by both Se and maternal nutritional plane. During the parturient process, HSe ewes tended to have greater (P = 0.06) concentrations of estradiol-17ß than ASe ewes. Three hours after parturition a surge of GH was observed in ASe-RES ewes that was muted in HSe-RES ewes and not apparent in other ewes. Growth hormone area under the curve during the parturient process was increased (P < 0.05) in ASe-RES vs HSe-RES ewes. Ewes that were overfed during gestation had reduced (P < 0.05) estradiol-17ß but greater IGF-I, triiodothyronine, and thyroxine (P < 0.05) compared with RES ewes. Even though ewes were transitioned to a common diet after parturition, endocrine status continued to be affected into lactation. Moreover, it appears that gestational diet may partially affect lactational performance through altered endocrine status.

Maternal dietary intake alters organ mass and endocrine and metabolic profiles in pregnant ewe lambs.

To determine the impacts of Se supply and maternal dietary intake on ewe organ mass and endocrine and metabolic changes throughout gestation, pregnant first parity ewes (n=77) were allocated to 6 treatments in a 2×3 factorial array. Factors included Se [adequate Se (ASe; 9.5µg/kg BW) vs. high Se (HSe; 81.8µg/kg BW)] initiated at breeding and dietary intake [60% (RES), 100% (CON), or 140% (EXC) of requirements] initiated on d 50 of gestation. Ewes were individually fed and blood samples from the jugular vein were obtained approximately every 14 d from d 50 until parturition. Maternal Se supply did not impact endocrine or metabolic status. There was a nutritional intake by day interaction for NEFA, blood urea nitrogen (BUN), insulin, triiodothyronine (T3), thyroxine (T4), progesterone (P4), and estradiol-17ß (E2). As expected, with increased maternal intake, NEFA concentrations were reduced. During the last weeks of gestation, BUN and insulin were elevated in EXC compared with RES ewes. Although the pattern of T3 and T4 differed throughout gestation within a treatment group, as maternal intake increased, circulating T3 and T4 were increased. For P4 and E2, as maternal dietary intake increased, there was a reduction in the steroid concentrations in jugular blood. There was only a main effect of maternal nutrition (P<0.001) for cortisol concentrations with EXC ewes having greater concentrations than RES and CON ewes, which did not differ. Although Se is known to influence thyroid hormone metabolism, supranutritional levels during pregnancy did not alter circulating T3 and T4 concentrations. Alterations in maternal endocrine status may have influenced placental transport of nutrients to the developing fetus, which we have shown previously is affected by maternal dietary Se and intake. In addition, the alterations in mammary gland weight that we observed may explain the impact of maternal nutrition on mammary gland function and colostrum production, thereby further impairing growth of developing neonates.

Maternal nutritional plane and selenium supply during gestation impact visceral organ mass and intestinal growth and vascularity of neonatal lamb offspring.

To investigate effects of nutritional plane and Se supply during gestation on neonatal offspring visceral organ mass and intestinal growth and vascularity, 84 nulliparous Rambouillet ewes (age = 240 ± 17 d, BW = 52.1 ± 6.2 kg) were allocated to a 2 × 3 factorial design. Ewes were fed 1 of 2 Se diets [adequate Se (ASe, 11.5 µg/kg BW) or high Se (HSe, 77.0 µg/kg BW)], initiated at breeding, and 1 of 3 nutritional planes [60% (restricted; RES), 100% (control; CON), or 140% (high; HIH) of NRC requirements], initiated at d 40 of gestation. Ewes were fed individually and remained on treatments through parturition. All lambs were removed from their dams at birth and fed milk replacer. At 20.6 ± 0.9 d of age, lambs were necropsied, visceral organs dissected, and jejunal samples collected. Lambs born to ewes fed CON and HIH had greater (P < 0.05) 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 treatments, 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 mRNA expression was greater (P ≤ 0.07) in lambs born to ewes fed RES compared with CON and HIH. Jejunal capillary size was affected (P = 0.09) by the interaction of nutritional plane × Se supply. 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 mass was affected by gestational nutrition, even when lambs had ad libitum intake and similar management postnatally. Despite similar small intestinal mass at 20 d of age, jejunal growth, vascularity, and gene expression were altered by maternal nutrition during gestation.

Impacts of maternal selenium supply and nutritional plane on visceral tissues and intestinal biology in 180-day-old offspring in sheep.

Objectives were to investigate the effects of maternal Se supply and nutritional plane during gestation on offspring visceral tissues and indices of intestinal growth, vascularity, and function at 180 d of age. Rambouillet ewe lambs (n = 82, approximately 240 d of age; 52 ± 0.8 kg BW at breeding) were allocated to a 2 × 3 factorial arrangement of treatments. Treatments included dietary Se [adequate Se (ASe, 9.5 µg/kg BW) or high Se (HSe, 81.8 µg/kg BW)] initiated at breeding and nutritional plane [60% (restricted, RES), 100% (control, CON), and 140% (high, HI) of requirements] initiated at d 50 of gestation. Ewes were fed pelleted diets and housed individually indoors. At parturition, lambs were immediately removed and fed artificial colostrum for the first 20 h followed by ad libitum access to milk replacer. At 180 ± 2 d of age, lambs were euthanized and tissues were harvested. Birth weight was affected by nutritional treatments (P < 0.001), with decreased birth weight in RES and HI compared with CON. Offspring from RES and HI ewes had decreased (P = 0.07) blood volume compared with CON, and those born to HSe ewes had increased (P < 0.04) total visceral adiposity. Within offspring from CON ewes, those from HSe ewes had greater (P < 0.02) intestinal mass compared with ASe ewes. Within offspring from HSe ewes, both RES and HI had reduced (P ≤ 0.05) intestinal mass compared with CON. Jejunal capillary area density was greater (P = 0.08) in offspring from ewes fed HSe compared with ASe. In addition, area per capillary was greater (P ≤ 0.09) in CON compared with RES. Maternal nutritional plane tended (P ≤ 0.11) to alter total small intestinal vascularity, with lambs from CON being greater than RES. Expression of most mRNA for measured angiogenic factors and receptors was not altered (P ≤ 0.13) by maternal treatments; however, expression of glucagon-like peptide-2 (GLP-2) was decreased (P = 0.07) in offspring from RES compared with CON ewes. Offspring from ewes fed HI diets had increased (P = 0.08) jejunal mucosal maltase activity. In conclusion, maternal Se supply and nutritional plane during gestation resulted in measurable changes in offspring visceral tissues and intestinal biology, including perirenal fat, blood volume, intestinal mass, total jejunal crypt cell proliferation, area per capillary in jejunal villi, GLP-2 mRNA expression, and maltase activity at 180 d. Additional work is needed to determine impacts on intestinal function and nutrient uptake.

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.

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 µg/kg BW) or high Se (HSe, 77.0 µg/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 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 at parturition. Ewes fed HIH had greater (P = 0.04) jejunal VEGF receptor-2 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.

Expression of gap junctional connexin proteins in ovine fetal ovaries: effects of maternal diet.

Gap junctions have been implicated in the regulation of cellular metabolism and the coordination of cellular functions during growth and differentiation of organs and tissues, and gap junctions play a major role in direct cell-cell communication. Gap junctional channels and connexin (Cx) proteins have been detected in adult ovaries in several species. Furthermore, it has been shown that several environmental factors, including maternal diet, may affect fetal organ growth and function. To determine whether maternal diet affects expression of Cx26, Cx32, Cx37, and Cx43 in fetal ovaries, sheep were fed a maintenance (M) diet with adequate (A) selenium (Se) or high (H) Se levels from 21 d before breeding to day 132 of pregnancy. From day 50 to 132 of pregnancy (tissue collection day), a portion of the ewes from the ASe and HSe groups was fed a restricted (R; 60% of M) diet. Sections of fetal ovaries were immunostained for the presence of Cxs followed by image analysis. All four Cxs were detected, but the distribution pattern differed. Cx26 was immunolocalized in the oocytes from primordial, primary, secondary, and antral follicles; in granulosa and theca layers of secondary and antral follicles; stroma; and blood vessels. Cx32 was in oocytes, granulosa, and theca cells in a portion of antral follicles; Cx37 was on the borders between oocyte and granulosa/cumulus cells of primordial to antral follicles and in endothelium; and Cx43 was on cellular borders in granulosa and theca layers and between oocyte and granulosa/cumulus cells of primordial to antral follicles. Maternal diet affected Cx26 and Cx43 expression, Cx26 in granulosa layer of antral follicles was decreased (P < 0.01) by HSe in the M and R diets, and Cx43 in granulosa layer of primary and granulosa and theca of antral follicles was increased (P < 0.05) by the M diet with HSe. Thus, Cxs may be differentially involved in regulation of fetal ovarian function in sheep. These data emphasize the importance of maternal diet in fetal growth and development.

Effects of maternal selenium supply and plane of nutrition during gestation on passive transfer of immunity and health in neonatal lambs.

To investigate the influence of maternal Se supply and plane of nutrition on lamb morbidity, mortality, and passive transfer of IgG, pregnant ewe lambs were used in 2 experiments with 2 × 3 factorial treatment arrangements. Supplementation of Se began at breeding and was either adequate Se (ASe, 9.5 µg/kg of BW) or high Se (HSe, 81.8 µg/kg of BW) in Exp. 1 or ASe (11.5 µg/kg of BW) or HSe (77.0 µg/kg of BW) in Exp. 2. On d 50 or 40 of gestation for Exp. 1 or 2, respectively, ewes were assigned randomly to 1 of 3 nutritional planes: 60% (RES), 100% (control, CON), or 140% (HI) of NRC requirements. This resulted in the following treatments: ASe-RES, ASe-CON, ASe-HI, HSe-RES, HSe-CON, and HSe-HI. Upon parturition, lambs were separated from their dams and serum samples obtained. Lambs were fed artificial colostrum for the first 20 h and then placed on milk replacer and grain pellets until completion of the study (Exp. 1, 57 d; Exp. 2, 21 d). Twenty-four hours after parturition, lamb serum samples were collected for IgG analysis. All lambs were reared similarly and morbidity and mortality assessed. Main effects were considered significant when P ≤ 0.05. In Exp. 1, there was a Se × plane of nutrition interaction (P ≤ 0.01) for lamb morbidity from birth to weaning and for 24-h IgG concentration. Lambs from ASe-RES and HSe-HI ewes were treated more frequently (P < 0.01) for respiratory and gastrointestinal disease, and lambs from HSe-HI ewes had the smallest (P < 0.01) 24-h serum IgG concentration. In Exp. 1, lambs from HI ewes also had the greatest (P < 0.01) mortality rates from birth to weaning compared with lambs from CON and RES ewes. In Exp. 2, there was an effect (P < 0.01) of maternal plane of nutrition with lambs from RES ewes having increased 24-h IgG compared with lambs from CON and HI ewes. There was no effect of maternal Se supplementation on lamb 24-h IgG in Exp. 2; however, there was a Se × plane of nutrition interaction (P < 0.01) for morbidity. From birth to 21 d of age, lambs from ASe-CON ewes had fewer (P < 0.01) treatment days compared with lambs from any of the other treatment groups. There also tended (P = 0.08) to be an effect of maternal Se supplementation on lamb mortality with increased mortality observed in lambs from HSe ewes. Results from the studies show a restricted maternal plane of nutrition can increase lamb serum IgG concentration. Selenium results were not consistent between the 2 experiments and may be due to differences in maternal Se.

Supranutritional selenium increases mammary gland vascularity in postpartum ewe lambs.

Objectives were to determine the effects of maternal dietary supranutritional Se and nutritional plane during gestation on capillary surface density, capillary area density, and angiogenic factor expression in the developing mammary gland of primiparous ewes. Selenium treatments were initiated at breeding [adequate Se (ASe; 9.5 µg/kg of body weight) vs. high Se (HSe; 81.8 µg/kg of body weight)] and nutritional planes at d 50 of gestation [Low, 60%; moderate (Mod), 100%; and High, 140% of requirements). Mammary glands were collected within 24h postpartum. Vascular development was assessed in the glandular portion of the mammary gland. Vascularity was determined for mammary tissue with the following measurements taken: the cross-sectional capillary area density (total capillary area as a proportion of tissue area) and capillary surface density (CSD; total capillary circumference per unit of tissue area). High-Se ewes had greater capillary surface and area densities compared with ASe ewes. A tendency existed for an Se × plane of nutrition interaction for CSD with maternal diet not affecting CSD in HSe ewes, but Low ewes had a decreased CSD compared with Mod ewes, with High being intermediate in ASe ewes. Moreover, HSe-Low and HSe-High ewes had increased CSD compared with ASe-Low and ASe-High, respectively. Although Se status did not influence angiogenic factor mRNA expression, mammary glands from Low ewes tended to have increased VEGF and FLT1 mRNA expression compared with High ewes, with Mod being intermediate. Maternal plane of nutrition did not affect mammary gland glutathione peroxidase activity, but it was increased in HSe compared with ASe ewes. Increased mammary capillary nutrient exchange area may contribute to previously observed changes in colostrum quality.

Maternal nutrition during pregnancy influences offspring wool production and wool follicle development.

The effects of maternal nutrition on offspring wool production (quality and quantity) were evaluated. Primiparous Rambouillet ewes (n = 84) were randomly allocated to 1 of 6 treatments in a 2 × 3 factorial design. Selenium treatment [adequate Se (ASe, 9.5 µg/kg of BW) vs. high Se (HSe, 81.8 µg/kg of BW)] was initiated at breeding, and maternal nutritional intake [control (CON, 100% of requirements) vs. restricted (60% of CON) vs. overfed (140% of CON)] was initiated at d 50 of gestation. Lamb birth weight was recorded at delivery, and all lambs were placed on the same diet immediately after birth to determine the effects of prenatal nutrition on postnatal wool production and follicle development. At 180 ± 2.2 d of age, lambs were necropsied and pelt weights were recorded. Wool samples were collected from the side and britch areas, whereas skin samples were collected from the side of each lamb only. Although Se status did not influence side staple length in males, female lambs born from ewes on the ASe treatment had a shorter staple length (P < 0.05) when compared with females from ewes on the HSe treatment. Maternal nutritional intake and Se status did not influence (P ≥ 0.23) wool characteristics on the britch. However, at the britch, wool from female lambs had a reduced comfort factor (P = 0.01) and a greater (P = 0.02) fiber diameter compared with wool from male lambs. Maternal Se supplementation, maternal nutritional plane, sex of the offspring, or their interactions had no effect (P > 0.13) on primary (29.10 ± 1.40/100 µm(2)) and secondary (529.84 ± 21.57/100 µm(2)) wool follicle numbers. Lambs from ASe ewes had a greater (P = 0.03) secondary:primary wool follicle ratio compared with lambs from HSe ewes (20.93 vs. 18.01 ± 1.00). Despite similar postnatal diets, wool quality was affected by maternal Se status and the maternal nutritional plane.

Nutritional plane and selenium supply during gestation affect yield and nutrient composition of colostrum and milk in primiparous ewes.

The objectives were to investigate effects of nutritional plane and Se supply during gestation on yield and nutrient composition of colostrum and milk in first parity ewes. Rambouillet ewe lambs (n = 84, age = 240 ± 17 d, BW = 52.1 ± 6.2 kg) were allocated to 6 treatments in a 2 × 3 factorial array. Factors included Se [adequate Se (ASe, 11.5 µg/kg of BW) or high Se (HSe, 77.0 µg/kg of BW)] initiated at breeding, and nutritional plane [60 (RES), 100 (CON), or 140% (HIH) of requirements] initiated at d 40 of gestation. Ewes were fed individually from d 40, and lambs were removed at parturition. Colostrum was milked from all ewes at 3 h postpartum, and one-half of the ewes (n = 42) were transitioned to a common diet meeting lactation requirements and mechanically milked for 20 d. Colostrum yield was greater (P = 0.02) for HSe ewes than ASe, whereas CON had greater (P < 0.05) colostrum yield than RES and HIH. Colostrum Se (%) was greater (P < 0.01) for HSe than ASe. Colostrum from ewes fed HSe had less (P = 0.03) butterfat (%), but greater (P ≤ 0.05) total butterfat, solids-not-fat, lactose, protein, milk urea N, and Se than ASe. Colostrum from HIH ewes had greater (P ≤ 0.02) solids-not-fat (%) than RES, whereas RES had greater (P ≤ 0.04) butterfat (%) than CON and HIH. Colostrum from ewes fed the CON diet had greater (P = 0.01) total butterfat than HIH. Total solids-not-fat, lactose, and protein were greater (P < 0.05) in colostrum from CON than RES and HIH. Ewes fed HSe had greater (P < 0.01) milk yield (g/d and mL/d) than ASe, and CON and HIH had greater (P < 0.01) yield than RES. Milk protein (%) was greater (P ≤ 0.01) in RES compared with CON or HIH. Ewes fed HSe had greater (P < 0.01) milk Se (µg/g and mg/d) than ASe on each sampling day. Milk from CON and HIH ewes had greater (P < 0.01) total solids-not-fat, lactose, protein, and milk urea N than RES. Total Se was greater (P = 0.02) in milk from ewes fed the CON diet compared with RES. Somatic cell count and total somatic cells were greater (P ≤ 0.05) in milk from CON than RES. A cubic effect of day (P ≥ 0.01) was observed for milk yield (g and mL). Butterfat, solids-not-fat, lactose, milk urea N, and Se concentration responded quadratically (P ≤ 0.01) to day. Protein (%), total butterfat, and total Se, and somatic cells (cells/mL and cells/d) decreased linearly (P < 0.01) with day. Results indicate that gestational nutrition affects colostrum and milk yield and nutrient content, even when lactational nutrient requirements are met.

Maternal selenium supplementation and timing of nutrient restriction in pregnant sheep: Impacts on nutrient availability to the fetus.

To determine the effects of maternal Se intake and plane of nutrition during mid or late gestation or both on AA concentrations and metabolite concentrations in the dam and fetus, pregnant ewe lambs (n = 64) were assigned to 1 of 8 treatments arranged in a 2 × 2 × 2 factorial array: Se level [initiated at breeding; adequate (ASe; 3.05 µg/kg of BW) or high (HSe; 70.4 µg/kg of BW)] and nutritional level [100% (control; CON) or 60% (restricted; RES) of NRC recommendations] fed at different times of gestation [d 50 to 90 (mid) or d 91 to 132 (late)]. A blood sample was obtained from each ewe and fetus on d 132 of gestation and used to measure circulating concentrations of glucose, NEFA, blood urea N, and AA. The late RES ewes and their fetuses had less (P ≤ 0.03) circulating glucose compared with late CON ewes and fetuses at d 132; however, no effect (P ≥ 0.14) of diet on the fetal:maternal glucose concentration ratio was observed. Late RES ewes had a smaller (P = 0.01) fetal:maternal NEFA ratio compared with late CON ewes. Ewes fed ASe had a greater (P = 0.01) fetal:maternal blood urea N ratio compared with HSe ewes. Fetal:maternal ratios of total circulating AA, total essential AA, and total nonessential AA were each affected (P ≤ 0.03) by the combination of Se treatment and late gestation nutritional level.

Impacts of maternal selenium and nutritional level on growth, adiposity, and glucose tolerance in female offspring in sheep.

To examine effects of maternal nutrition and Se intake on adiposity and insulin sensitivity in female offspring, treatments were imposed during gestation on 82 pregnant primiparous Rambouillet ewe lambs (52.2 ± 0.8 kg) allotted randomly to 1 of 6 treatments in a 2 × 3 factorial arrangement. Factors were adequate (9.5 µg Se·kg BW(-1)·d(-1); ASe) or high (81.8 µg Se·kg BW(-1)·d(-1); HSe) levels of dietary Se (Se-enriched yeast) and maternal nutritional intake (100% of metabolizable energy [ME] requirement [MOD], 60% of MOD [LOW], and 140% of MOD [HIGH]). Selenium treatments were initiated at breeding and global nutritional treatments at day 50 of gestation. At parturition, lambs were removed from ewes before nursing and managed similarly. Glucose tolerance tests were performed at 107 and 148 d of age. Necropsies were performed at 180 d of age. Although there was no effect of Se on maternal body condition or weight during gestation, both maternal nutritional intake and selenium treatment influenced (P ≤ 0.04) offspring growth and response to a glucose tolerance test. Female lambs from HSe ewes were heavier (P = 0.04) at birth. There were nutritional intake and Se interactions (P ≤ 0.05) on the growth rate of the lambs and their insulin response to a glucose bolus at 2 different times during growth. By 180 d, ewe lambs from HSe ewes had more (P ≤ 0.07) internal fat stores than lambs from ASe ewes. It appears that both maternal nutritional level and Se intake can influence insulin sensitivity, and maternal Se intake alone can enhance fat deposition in female offspring.

Ovine offspring growth and diet digestibility are influenced by maternal selenium supplementation and nutritional intake during pregnancy despite a common postnatal diet.

Lambs born from feed-restricted or overfed ewes can be lighter at birth, whereas maternal Se supplementation can increase fetal size near term. We hypothesized that birth weight would be inversely related to feed efficiency and growth rates during postnatal development. To examine the effects of maternal dietary Se and nutrient restriction or excess on postnatal lamb growth, diet digestibility, and N retention, 82 ewe lambs (52.2 ± 0.8 kg) were allotted randomly to 1 of 6 treatments in a 2 × 3 factorial arrangement. Factors were dietary Se [adequate Se (9.5 µg/kg of BW; ASe) vs. high Se (Se-enriched yeast; 81.8 µg/kg of BW; HSe)] and maternal nutritional intake [60% (restricted, RES), 100% (control, CON), or 140% (high, HI) of NRC requirements]. Selenium treatments began at breeding. Nutritional treatments began on d 50 of gestation. Lambs were immediately removed from their dams at parturition, provided artificial colostrum, and fed milk replacer until weaning. After weaning, lambs were maintained using common management and on common diets until necropsy at 180 d. Male and female lambs from RES-fed ewes were lighter (P ≤ 0.03) at birth than lambs from CON-fed ewes, with lambs from HI-fed ewes being intermediate. Although maternal nutritional intake influenced (P < 0.06) BW gain before weaning on d 57, both maternal nutritional intake and sex of offspring influenced (P ≤ 0.09) BW gain from d 57 to 180. Although maternal nutritional intake did not influence (P ≥ 0.35) female lamb BW gain, male lambs from RES-fed ewes were lighter (P ≤ 0.09) than those from CON-fed ewes until d 162. By d 180, male lambs from RES- and HI-fed ewes were lighter (P ≤ 0.09) than those from CON-fed ewes. In a subset of lambs used in a feed efficiency study, namely, those born to ASe ewes, HI maternal nutritional intake decreased (P ≤ 0.09) ADG and G:F compared with lambs born to RES- and CON-fed ewes, which did not differ (P ≥ 0.60). Conversely, when lambs were born to HSe ewes, HI maternal nutritional intake increased (P ≤ 0.01) ADG and G:F compared with CON, with RES being intermediate. Moreover, lambs born to ASe-HI ewes had decreased (P < 0.01) ADG and G:F compared with lambs born to HSe-HI ewes. Furthermore, male lambs had a greater (P < 0.01) G:F than female lambs. Maternal diet did not affect (P ≥ 0.11) N retention in male lambs. These data indicate that maternal nutrition during gestation and sex of the offspring alter postnatal growth and efficiency of growth in offspring despite similar postnatal management.

Maternal dietary restriction and selenium supply alters messenger ribonucleic acid expression of angiogenic factors in maternal intestine, mammary gland, and fetal jejunal tissues during late gestation in pregnant ewe lambs.

The objectives of this study were to evaluate effects of maternal dietary restriction and Se supply on angiogenic factor mRNA expression in intestinal and mammary tissues, and jejunal crypt cell proliferation and vascularity in late-term fetal intestines. In Exp. 1, pregnant ewe lambs (n = 32; initial BW = 45.6 +/- 2.3 kg) were allotted randomly to 1 of 4 treatments. Treatments (initiated d 50 +/- 5 of gestation) were control (3.5 microg of Se.kg of BW(-1).d(-1)), Se-wheat (75 microg of Se.kg of BW(-1).d(-1)), selenate (Se3; providing 75 microg of Se.kg of BW(-1).d(-1)), selenate (Se15; providing 375 microg of Se.kg of BW(-1).d(-1)). Diets (DM basis) were similar in CP (15.5%) and ME (2.68 Mcal/kg). In Exp. 2, pregnant ewe lambs (n = 36; initial BW 53.8 +/- 1.3 kg) were allotted randomly to treatments in a 2 x 2 factorial arrangement. Factors were nutrition (control, 100% of requirements vs. restricted nutrition, 60% of controls) and dietary Se (adequate Se; 6 microg of Se.kg of BW(-1).d(-1) vs. high Se; 80 microg of Se.kg of BW(-1).d(-1)). Selenium treatments were initiated 21 d before breeding, and nutritional treatments were initiated on d 64 of gestation. Diets (DM basis) were 16% CP and 2.12 Mcal/kg of ME. In Exp. 1, Se15 increased (P = 0.07) vascular endothelial growth factor (VEGF) mRNA expression, whereas Se supplementation decreased (P = 0.06) kinase insert domain receptor (KDR) mRNA in maternal mucosal scrape on d 134 of gestation. Expression of VEGF mRNA was decreased by Se (P = 0.10) in fetal jejunum. In mammary tissue, fms-related tyrosine kinase 1 and KDR mRNA were greater in Se-wheat compared with Se3, and KDR expression was increased (P = 0.10) in Se15 compared with Se3. In Exp. 2, dietary restriction increased (P < or = 0.07) expression of mRNA for VEGF, fms-related tyrosine kinase 1, KDR, neuropilin 1, neuropilin 2, and hypoxia-inducible factor 1, alpha subunit in mucosal scrapes from maternal jejunum. In fetal jejunum, soluble guanylate cyclase, was decreased (P = 0.01) by maternal dietary restriction from d 64 to 135 of gestation. Total microvascularity in fetal jejunum was reduced (P = 0.002) by maternal dietary restriction. Mammary gland expression of VEGF, neuropilin 1, angiopoietin receptor (endothelial tyrosine kinase), and endothelial nitric oxide synthase 3 increased (P < or = 0.09), whereas angiopoietin 1 decreased (P = 0.05) due to nutrient restriction. Data indicate that expression of angiogenic factors and receptors in maternal intestine, mammary gland, and fetal jejunum are responsive to maternal nutrition and likely explain observed changes in tissue vascularity.

Effects of plane of nutrition and selenium supply during gestation on ewe and neonatal offspring performance, body composition, and serum selenium.

To investigate the 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 arrangement of treatments. Factors included Se [adequate Se (ASe, 11.5 microg/kg of BW) or high Se (HSe, 77.0 microg/kg of BW)] initiated at breeding, nutritional plane [60% (restricted, RES), 100% (control, CON), or 140% (high, HIH) of NRC requirements] initiated at d 40 of gestation, and physiological stage at necropsy [3 to 24 h postpartum or d 20 of lactation]. Ewes were fed and housed individually in a temperature-controlled facility. At parturition, all lambs were removed and artificially reared until necropsy on d 20.6 +/- 0.9 of age. Ewes assigned to the treatment at d 20 of lactation were transitioned to a common diet meeting lactation requirements and were mechanically milked. From d 95 of gestation through parturition and d 20 of lactation, ewe BW and BCS were least (P

Cotyledonary responses to maternal selenium and dietary restriction may influence alterations in fetal weight and fetal liver glycogen in sheep.

To examine the effects of maternal supranutritional selenium (Se) and nutrient restriction during mid and late gestation on placental characteristics and fetal liver glycogen, ewes received either adequate Se (ASe) or high Se (HSe) prior to breeding. On d 64 of gestation, ASe and HSe ewes remained at 100% of requirements (controls; CON) or were restricted (RES; 60% of requirements). On d 135 of gestation, fetal weight (P< or =0.08) was greatest in both HSe and CON ewes. Placentome number, mass, and caruncular and cotyledonary weight were not different (P> or =0.17) among treatments. Fetal mass:placental mass ratio was less (P=0.06) in RES compared to CON ewes. Compared to ASe, HSe exhibited increased (P< or =0.08) cellular proliferation and DNA concentration and decreased (P=0.07) cellular size in cotyledonary tissue. Nutritional restriction decreased (P< or =0.08) cotyledonary protein concentration and cellular size. VEGF receptor 1 (Flt) mRNA in cotyledonary tissue was greater in HSe compared with ASe ewes (P=0.06) and in RES compared with CON ewes (P=0.08). There was no effect of diet on caruncular growth variables (P> or =0.13) or on placental vascularity (P> or =0.11). Progesterone was greater (P< or =0.08) in ASe-RES ewes compared to all groups at d 90 and ASe-CON and HSe-CON at d 104. Although fetal glucose and cortisol concentrations were not affected by diet, fetal liver glycogen was greater (P=0.04) in ASe-RES compared to ASe-CON and HSe-RES ewes with HSe-CON being intermediate. Both Se and nutritional plane may impact placental function and fetal growth, as fetal weight and liver glycogen are altered despite similar placental vascularity measurements.

Maternal selenium supplementation and timing of nutrient restriction in pregnant sheep: effects on maternal endocrine status and placental characteristics.

To determine the effects of maternal Se intake and plane of nutrition during midgestation, late gestation, or both on hormone and metabolite concentrations in the dam and on placental characteristics, pregnant ewe lambs (n = 64) were assigned to 1 of 8 treatments arranged in a 2 x 2 x 2 factorial array: Se level [initiated at breeding; adequate (3.05 microg/kg of BW) or high (70.4 microg/kg of BW)] and nutritional level [100% (control) or 60% (restricted) of NRC recommendations] fed at different times of gestation [d 50 to 90 (midgestation) or d 91 to 130 (late gestation)]. The control ewes had a greater (P = 0.01) percentage change in BW from d 50 than restricted ewes during both mid- and late gestation. Although blood urea N was not affected by either Se or nutritional level, restricted ewes had greater (P = 0.01) concentrations of circulating Se on d 66, 78, 106, 120, and 130 of gestation compared with control ewes. Both Se and timing of the nutritional level affected circulating progesterone; however, only nutritional level affected thyroxine and triiodothyronine concentrations in the dam. Nutrient restriction during late gestation decreased (P or= 0.1) placental, caruncular, or cotyledonary weights, cotyledonary cellular proliferation was decreased (P < 0.05) in ewes receiving a high concentration of Se compared with those receiving adequate Se. In addition, either Se or nutritional level affected vascular endothelial growth factor (VEGFA), VEGFA-receptor 1, VEGFA-receptor 2, and NO synthase mRNA abundance in the cotyledonary tissue. In the caruncular tissue, either Se or nutritional level affected VEGFA-receptor 1, placental growth factor, and NO synthase mRNA abundance. Selenium supplementation and the duration or timing of nutrient restriction appear to influence the endocrine and metabolic status of the ewe, which may influence nutrient transport and placental function.