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Thirty-two Angus-influenced steers (255 ± 15.1 kg) were used to evaluate the effect of duration of exposure to a high-concentrate-based diet after weaning prior to forage finishing on performance, plasma insulin and glucose levels, carcass characteristics, and tissue fatty acid composition. Steers were randomly assigned to 1 of 4 feeding treatments: 0 d on high concentrate (CNT), 40 d on high concentrate, 80 d on high concentrate (80D), and 120 d on high concentrate (120D) followed by finishing on pasture to 485 kg. The high-concentrate diet consisted of cracked corn, corn gluten feed, chopped hay, and mineral supplement; high-quality pasture included winter annuals (ryegrass and oats), alfalfa, and nontoxic tall fescue. Weight and blood samples were collected at 21-d intervals. At 24 h postmortem, carcass characteristics and a rib section (11th-12th rib) from the left side was collected for proximal analysis and a section of subcutaneous adipose tissue collected for histology cell sizing. Due to harvesting steers at equal final BW, there was no difference for total gain or total ADG (P > 0.19); however, HCW and dressing percentage linearly increased (P < 0.031) with time on concentrate. There was no difference across treatments for rib eye area or yield grade (P > 0.11), but 12th-rib fat thickness and KPH fat quadratically and linearly increased (P < 0.015), respectively. Marbling score and total lipid of the longissimus dorsi (LM) linearly increased with time on concentrates (P < 0.001). This increase in lipid within the LM resulted in a linear decrease with increased time on concentrate for moisture (P < 0.001). Crude protein content of the LM quadratically differed (P = 0.001) and was the greatest in steers from 80D whereas 120D had the least. Within the LM, there was no difference across treatments for SFA or MUFA (P > 0.27) whereas n-6 PUFA quadratically differed (P = 0.002), being the greatest at 80D, and n-3 PUFA linearly decreased as time on concentrates increased (P < 0.001). These changes in n-6 PUFA and n-3 PUFA resulted in a linear increase of the n-6:n-3 PUFA ratio as time on concentrate increased (P < 0.001). There was no difference across treatments for plasma glucose concentration (P > 0.64), whereas there was an interaction between treatment and time for plasma insulin concentration (P = 0.012), with a quadratic difference across treatments, with the greatest levels occurring in the CNT and 120D treatments. The consumption of a high-concentrate-based diet immediately after weaning increases dressing percentage, carcass weight, and marbling deposition in cattle subsequently finished on forages. [ABSTRACT FROM AUTHOR]

Previous research has shown that exposure to ergot alkaloids found in endophyte-infected (Epichloë coenophiala) tall fescue (Lolium arundinaceum) results in decreased vasoactivity. Little is known regarding the effect ergot alkaloid exposure during gestation may have on vasculature supporting the fetus. The objective of this study was to evaluate contractile responses of uterine and umbilical arteries collected from ewes consuming ergot alkaloids during gestation. On d 35 of gestation, 36 Suffolk ewes (78.24 ±9.5 kg) were randomly assigned to endophyte-infected (E+) or endophyte-free (E-) tall fescue seed treatments that were fed either throughout or switched on d 86 of gestation, creating four seed treatments E+E+, E+E-, E-E+, E-E-. Ewes were fed E+ tall fescue seed to provide 1.77 mg of total ergovaline/head/d with E- ewes receiving the same quantity of E- seed. Gestation was terminated on d 133, and sections of uterine artery and umbilical cord were surgically collected. Only collections from 28 ewes (n = 7/treatment) were of sufficient viability to proceed with the contractility experiments. Arteries were cleaned, sliced into 2-mm cross sections, and suspended in multi-myograph chambers containing 5 mL of continuously oxygenated Krebs-Henseleit buffer. Vessels were exposed to increasing concentrations (5x10-8 to 1x10-4 M) of norepinephrine, serotonin, ergotamine, and ergovaline (5x10-9 to 1x10-5 M; extract of tall fescue seed) in 15-min intervals. Data were normalized as a percentage of the maximum contractile response induced by a reference dose of 120 mM KCl. Data from each artery were analyzed using mixed models of SAS as a split-plot with seed and myograph treatments as the whole and sub-plot treatments, respectively. Increasing concentrations of norepinephrine generated a moderate contractile response by the uterine artery (P < 0.05), but no response in the umbilical artery. Increasing concentrations of serotonin resulted in negligible responses in uterine preparations, whereas umbilical artery preparations were very responsive (P < 0.05) to serotonin. Ewes receiving E+E+ and E-E+ treatments had decreased vasoactivity in umbilical arteries to serotonin with a dextral shift in concentrations where the response curve initiated (P < 0.05). Interestingly, uterine arteries were not responsive to exposure to ergotamine or ergovaline, whereas umbilical arteries were very responsive. Umbilical arteries collected from ewes receiving E-E- and E+E- were more vasoactive to ergot alkaloids (P < 0.05) than other treatments. These findings indicate that maternal blood supply to the placenta is protected from negative effects of ergot alkaloids; however, umbilical vasculature is not and this could negatively affect fetal growth. [ABSTRACT FROM AUTHOR]

Twelve Angus-influenced steers (227 ± 10.1 kg) were used to evaluate the effect of duration of exposure to a high-concentrate-based diet after weaning prior to forage finishing on plasma insulin and glucose levels under challenge and lipogenic gene expression. Steers were randomly assigned to 1 of 4 feeding treatments--0 d on high concentrate (CNT), 40 d on high concentrate, 80 d on high concentrate, and 120 d on high concentrate (120D)--followed by finishing to 485 kg on pasture. The high-concentrate diet consisted of cracked corn, corn gluten feed, chopped hay, and mineral supplement, whereas high-quality pasture included winter annuals (ryegrass and oats), alfalfa, and nontoxic fescue. Weights and blood samples were collected at 21-d intervals. Muscle biopsies taken from the right longissimus dorsi (LM) when steers started the feeding period and at their respective days on treatment. Intravenous glucose tolerance tests (IVGTT) were performed at 40-d intervals until 160 d. At 24 h postmortem, carcass characteristics and a rib section (11th-12th rib) from the left side was collected for proximate analysis. There was an interaction between treatment and time for plasma glucose concentration (P = 0.03), whereas there was no interaction and no difference across treatments for plasma insulin concentration (P > 0.20). There was no difference across treatments for initial glucose concentration during IVGTT (P = 0.86) whereas adjusted area under the curve for glucose concentration linearly decreased as treatment increased (P = 0.022), with CNT and 120D being significantly different at 120 d (P = 0.008). There was no difference across treatments for initial insulin concentration during IVGTT (P = 0.46), however, 120D had a greater initial insulin concentration than CNT at 120 d (P = 0.024). Adjusted area under the curve for insulin was not different across treatments (P < 0.40). Gene expression of acetyl CoA carboxylase, stearoyl CoA desaturase, and glucose transporter 4 were not different (P > 0.21) between CNT and 120D at 120 d. Fatty acid synthase mRNA expression increased 3.2-fold (P < 0.05) for 120D compared with CNT and the ΔCT values for FASN correlated (-0.80; P < 0.017) to the quantity of de novo lipogenesis products within the LM at the time of harvest. The consumption of a high-concentrate-based diet immediately after weaning may alter insulin and glucose dynamics and lipogenic gene expression of cattle finished in a pasture-based system. [ABSTRACT FROM AUTHOR]

Differential microRNA (miRNA) expression levels have been reported for placental tissues in cases of uteroplacental insufficiency and fetal growth restriction. Ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh] seed induces intrauterine growth restriction (IUGR) due to uteroplacental insufficiency. The objective of this study was to assess the impact on placental miRNA levels due to consumption of ergot alkaloids during mid to late gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to 1 of 2 treatments--endophyte-free tall fescue seed (E-; 0.0 μg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 μg ergovaline + ergovalinine/g)--from d 35 through 85 and d 86 through 133 of gestation, creating 4 unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1,772 μg of ergovaline + ergovalinine/ewe per day for E+ treatments, and an equal weight of endophyte-free seed (0.0 μg ergovaline + ergovalinine) was fed for E-treatments. Ewes were pair fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Placental samples were weighed, frozen in liquid nitrogen, and stored at -80°C. Total RNA was extracted from cotyledon placental tissue using TRIzol and a PureLink RNA Mini Kit (ThermoFisher Scientific). Total RNA was quantified and quality was assessed using an Agilent 2100 Bioanalyzer. Ribonucleic acid integrity numbers of >7 were considered sufficient quality. A subsample (n = 4) was selected for both the E+E+ and E-E-treatment groups, and total cotyledon RNA was submitted for gene expression profiling via Illumina RNA-Seq (LC Sciences). Numerous miRNA transcripts were upregulated (P < 0.01; n = 15) in E+E+ compared with E-E- and included miR-21, miR-221, miR-99a, miR-152, miR-381, miR-30a, miR-143, and miR-122. miR-21 exhibited a 9.89-fold increase in expression level for E+E+ compared with E-E-. miR-21 has previously been implicated as a potential biomarker for fetal hypoxia due to upregulation in both placental and plasma/serum samples. Similar increases in miR-21 and miR-122 levels have been correlated to other pathological diseases of the placenta including placental insufficiency, IUGR, and preeclampsia. [ABSTRACT FROM AUTHOR]

Consuming ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] seed causes intrauterine growth restriction due to uteroplacental insufficiency. The objective of this study was to assess the impact on gene expression levels in placental tissue from feeding ergot alkaloids during gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to 1 of 2 treatments--endophyte-free tall fescue seed (E-; 0.0 μg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 μg ergovaline + ergovalinine/g)--from d 35 through 85 and d 86 through 133 of gestation, creating 4 unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1,772 μg of ergovaline + ergovalinine/ewe per day for E+ treatments, and an equal weight of endophytefree seed (0.0 μg ergovaline + ergovalinine) was fed for E-treatments. Ewes were pair fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Placental samples were weighed, frozen in liquid nitrogen, and stored at -80°C. Total RNA was extracted from cotyledon placental tissue using TRIzol and a PureLink RNA Mini Kit (ThermoFisher Scientific). Total RNA was quantified and quality was assessed using an Agilent 2100 Bioanalyzer. Ribonucleic acid integrity numbers of >7 were considered sufficient quality. A subsample (n = 4) was selected for both the E+E+ and E-E-treatment groups, and total cotyledon RNA was submitted for gene expression profiling via Illumina RNA-Seq (LC Sciences). Numerous genes were upregulated (P ≤ 0.01; n = 131) in E+E+ compared with E-E- and included genes involved in angiogenesis and vasoconstriction (FGA, APOH, and HPX), hemostasis and coagulation (KNG1, FGA, PLG, and FGB), oxidative reduction (PYROXD2 and CYP2E1), cholesterol import and lipoprotein particles (APOC3, APOH, APOA2, GC, and PON1), cell activation (FGA), and immune response (KNG1 and AHSG). Several genes were downregulated (P < 0.01; n = 56) in E+E+ compared with E-E-, including genes involved in fatty acid metabolism, lipid oxidation, and beta-oxidation (ADIPOQ), G-protein coupled receptor (GPR151), signal transduction (HRH4), and cell proliferation (PODN). The consumption of ergot alkaloids during gestation directly effects the mRNA expression in cotyledon tissues. [ABSTRACT FROM AUTHOR]

Color Doppler ultrasonography was used to assess ergot alkaloid-induced vasoconstriction in pregnant ewes (Ovis aries) that were fed diets with or without toxic endophyte-infected seed of tall fescue (Lolium arundinaceum). A fungal endophyte (Epicloë coenophialia)that infects most plants of the standard cultivar of tall fescue, 'Kentucky 31,' produces ergot alkaloids that can cause a persistent constriction of blood flow in grazing ruminants, which incapacitates the animal's ability to thermo-regulate core body temperature. Suffolk ewes were stratified by BCS for random assignment to four treatment groups (n = 15/treatment). Either endophyte-free (E-) or endophyte-infected (E+) tall fescue seed were fed in similar diet concentrations such that the daily consumption of ergovaline and ergovalanine for E+ was 1,772 µg/ewe/d mixed in a TMR (corn, soybean meal, and cottonseed hulls). The ewes were fed the TMR without seed for the first 35 d. On day 35, ewes were fed endophyte-free (E-) or endophyte-infected (E+) seed, and on day 86, half of each group was switched to the opposite treatment (E-E+ or E+E-) and half remained on the same treatment (E-E- or E+E+) to parturition. Ultrasound imaging of left carotid artery was done at the start of lambing and the range in days on fed seed ranged from 50 to 106 days. Color Doppler ultrasonography was performed using a Classic Medical TeraVet 3000 Ultrasound Unit (Classic Universal Ultrasound, Tequesta, FL) with a 12L5-VET (12 MHz) linear array transducer. Cross-sectional area of the left carotid artery was measured for each ewe to determine luminal area, and a Power Doppler image was collected for measuring peak systolic and end diastolic velocities, heart rate, and pulsatility and resistance indices. Luminal areas were similar (P > 0.5) between E-E- (28.8 ± 1.98 mm2) and E+E- (30 ± 1/85 mm2) treatments, and between E+E+ (17.0 ± 2.06 mm2) and E-E+ (17.5 ± 2.06 mm2). Carotid arteries with E-E- and E+E- treatments were relaxed (P < 0.001) in comparison to those with the E+E+ and E-E+ treatments. Although there were no treatment effects (P > 0.10) on peak systolic and end diastolic velocities or heart rate, pulsatility and resistance indices were greater (P < 0.05) for E+E+ and E-E+ than for E-E- and E+E- treatments. Results indicated a vasoconstrictive response of the carotid arteries in pregnant ewes exposed to ergot alkaloids, but vascular recovery was demonstrated for sheep that had been switched from E+ to E- diets. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of genotype in ewes consuming ergot alkaloids found in endophyte-infected tall fescue seed. Genotype at the DRD2 gene has been associated with serum prolactin concentrations in beef cattle grazing E+ tall fescue. Genomic DNA samples were obtained from 32 Suffolk ewes and used to initially screen the ovine DRD2 gene for SNP. One SNP in exon I, g270a, was discovered and further investigated due to favorable allele and genotypic frequencies. Allele frequencies at the g270a SNP were 0.64 for G and 0.36 for A; genotypic frequencies were 0.47, 0.34, and 0.19 for GG, AG, and AA genotypes, respectively. A genotyping assay was designed, tested, and found to be 100% concordant with sequencing results. Pregnant ewes (n = 32) were fed 1 of 2 dietary treatments--endophyte-free tall fescue seed (E-; 0.0 µg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g)--during 2 time periods--d 35 through 85 (T2) and d 86 through 133 (T3) of gestation--in a 2 × 2 factorial arrangement. Endophyte-infected seed was fed at a level of 1,772 µg of ergovaline + ergovalinine/ewe per day for E+ treatments and an equal weight of endophyte-free seed for E- treatments. All ewes were pair fed across treatments to maintain equal DMI. Data were analyzed with dietary treatment (E+ or E-), time of gestation (T2 or T3), genotype (AA, AG, and GG), and all interactions in the model. Significance was set at P < 0.05. Prolactin concentrations during gestation were higher for AA and AG than GG genotype regardless of dietary treatment or gestation time. Lamb fetal weight was reduced due to E+ exposure during T3 but did not differ by ewe genotype or any interactions with treatment or gestation time. A subsample (n = 16) of ewes were used to assess changes in cortisol and thyroid hormones (Th3, triiodothyronine, and thyroxine). Cortisol, triiodothyronine, and thyroxine concentrations were elevated in AA genotype compared with GG. Dietary treatment, gestation time, or interactions with genotype had no effect on cortisol, triiodothyronine, or thyroxine. Genotype at the ovine DRD2 SNP appears to be associated with circulating hormone concentrations in the ewe, regardless of dietary fescue treatment or stage of gestation. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate uteroplacental sufficiency, fetal growth, and development in ewes consuming ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh; Schedonorus phoenix (Scop.) Holub] seed at two stages of gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to one of two treatments: endophyte-free tall fescue seed (E-; 0.0 µg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g) from d 35 - d 85 and d 86 - d 133 of gestation creating four unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1772 µg of ergovaline + ergovalinine/hd/d for E+ treatments while an equal weight of endophyte-free seed (0.0 µg ergovaline + ergovalinine) was fed for E- treatments. Ewes were pair-fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Muscle, organ, and placental samples were weighed and stored at -20°C and -80°C for later analysis. Data were analyzed as a randomized block design using a 2 x 2 factorial with alkaloid consumption (Eor E+), gestational time period (d 35 - d 85 or d 86 - d 133), and interaction as fixed effects. There was no significant difference (P > 0.05) in actual placental or fetal weights based on E+ or E- treatment between d 35 - d 85. A significant (P = 0.036) interaction between treatment and time was observed wherein the placentome weight to BW ratio was highest for E+E- ewes. Ewes receiving E+ treatment between d 86 - d 133 had lower (P = 0.003) uterine weights and lower (P = 0.0005) placentome weights. Cotyledon and caruncle tissue weights were reduced (P < 0.002) in ewes on E+ treatment between d 86 - d 133 compared to E- treatment. Cotyledon and caruncle weights were reduced by 25% and 19%, respectively. Overall fetal weight was decreased (P = 0.002) by 10% for ewes on E+ treatment compared to E- treatment between d 86 - d 133. Ergot alkaloid exposure during late gestation induces uteroplacental insufficiency and leads to reduced fetal growth. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate uteroplacental sufficiency, fetal growth, and development in ewes consuming ergot alkaloids found in endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh; Schedonorus phoenix (Scop.) Holub] seed at two stages of gestation. Thirty-six Suffolk ewes (78.24 kg ± 9.5) estimated to be carrying twins at d 35 of gestation were randomly assigned to one of two treatments: endophyte-free tall fescue seed (E-; 0.0 μg ergovaline + ergovalinine/g) or endophyte-infected tall fescue seed (E+; 4.14 μg ergovaline + ergovalinine/g) from d 35 - d 85 and d 86 - d 133 of gestation creating four unique dietary treatments: E-E-, E-E+, E+E-, and E+E+. Endophyte-infected tall fescue seed was fed at a level to provide 1772 μg of ergovaline + ergovalinine/hd/d for E+ treatments while an equal weight of endophyte-free seed (0.0 μg ergovaline + ergovalinine) was fed for E- treatments. Ewes were pair-fed across treatments in order to maintain equal DMI. Fetal and maternal necropsies were performed at d 133 of gestation. Muscle, organ, and placental samples were weighed and stored at -20°C and -80°C for later analysis. Data were analyzed as a randomized block design using a 2 x 2 factorial with alkaloid consumption (Eor E+), gestational time period (d 35 - d 85 or d 86 - d 133), and interaction as fixed effects. There was no significant difference (P > 0.05) in actual placental or fetal weights based on E+ or E- treatment between d 35 - d 85. A significant (P = 0.036) interaction between treatment and time was observed wherein the placentome weight to BW ratio was highest for E+E- ewes. Ewes receiving E+ treatment between d 86 - d 133 had lower (P = 0.003) uterine weights and lower (P = 0.0005) placentome weights. Cotyledon and caruncle tissue weights were reduced (P < 0.002) in ewes on E+ treatment between d 86 - d 133 compared to E- treatment. Cotyledon and caruncle weights were reduced by 25% and 19%, respectively. Overall fetal weight was decreased (P = 0.002) by 10% for ewes on E+ treatment compared to E- treatment between d 86 - d 133. Ergot alkaloid exposure during late gestation induces uteroplacental insufficiency and leads to reduced fetal growth. [ABSTRACT FROM AUTHOR]

Ergot alkaloids, a class of mycotoxins, induce vasoconstriction when consumed by animals and humans. Pregnant ewes ( n = 16; 81.2 kg ± 7.7) were assigned fed endophyte-infected tall fescue seed ( E+ ; 4.14 μg ergovaline + ergovalinine/g seed) or a control diet ( CON ; 0 μg ergovaline + ergovalinine) for increasing duration during late gestation (from gd86 to gd110 or gd133) to examine changes in placentome morphology and mRNA transcriptome, and fetal development. Exposure to E+ fescue reduced serum prolactin concentrations at gd110 and gd133 demonstrating treatment efficacy. For control ewes, cotyledon and total placentome weights decreased with advancing gestation due to remodeling of placental tissues; however, cotyledon and placentome weight did not change with advancing gestation in E+ fed ewes. Fetal brain sparing was evident in E+ exposed fetuses at gd110 and gd133 compared to CON, which demonstrates asymmetrical growth and intrauterine growth restriction. Mycotoxin exposure (E+) resulted in differential expression of 22 genes in the cotyledon tissue at gd110 but only one gene at gd133 compared to CON. These results suggest that the response to mycotoxin exposure in the pregnant sheep model has an immediate impact on placental remodeling and fetal development that persists throughout the duration of the exposure period.