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Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses.

ABSTRACT: Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue and is detrimental to growth and performance. Recent research has shown that supplementing protein has the potential to enhance growth performance in weaned steers. Therefore, the objective of this study was to evaluate the effect of supplemental CP on physiological parameters in stocker steers experiencing fescue toxicosis. Thirty-six weaned Angus steers (6 mo of age) stratified by weight (196.1 ± 3.6 kg) were assigned to a 2 × 2 factorial arrangement for 56 d: endophyte-free (EF) seed and 14% CP (EF-14; n = 9), EF seed and 18% CP (EF-18; n = 9), endophyte-infected (EI) seed and 14% CP (EI-14; n = 9), and EI seed and 18% CP (EI-18; n = 9). Steer growth and hemodynamic responses were collected weekly during ergot alkaloid exposure. On day 14 of the trial, iButton temperature data loggers were subcutaneously inserted in the lateral neck region to record hourly body temperature for 42 d. Data were analyzed using PROC MIXED of SAS with repeated measures. No differences were observed in DMI, BW, ADG, F:G, or BCS during the treatment period (P > 0.05). Hair shedding scores, rectal temperatures, surface temperatures, and respiration rates were greater in EI steers compared to EF steers regardless of supplemental CP (P < 0.05). However, subcutaneous body temperature was greater in EI-14 steers (37.94 °C) compared to other steer groups (37.60, 37.68, 37.72 ± 0.04 °C for EF-14, EF-18, and EI-18, respectively; P < 0.05). Prolactin concentrations tended to be greater in EF steers when compared to EI steers (P = 0.07). Heart rate and hematocrit were reduced for EI-18 steers compared to other steer groups (P < 0.05). Caudal artery diameter was reduced in EI-18 steers compared to EI-14 steers (2.60 vs. 2.75 ± 0.05 mm, respectively; P < 0.05) and caudal vein diameter was reduced in EI-18 steers (3.20 mm) compared to all other steer groups (3.36, 3.39, 3.50 mm for EF-14, EF-18, and EI-14, respectively; P < 0.05). However, there was no difference observed in systolic or diastolic blood pressure during the treatment period (P > 0.05). Based on the data, exposure to low to moderate levels of ergot alkaloids during the stocker phase had a negative impact on hemodynamic responses and supplemental CP had minimal impact to alleviate symptoms. Therefore, feeding additional protein above established requirements is not expected to help alleviate fescue toxicosis.

SUBMITTER: Poole RK

PROVIDER: S-EPMC6735711 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses.

Poole Rebecca K RK Womble Carrisa M CM Poore Matthew H MH Poole Daniel H DH Pickworth Carrie L CL

Journal of animal science 20190901 9

Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue and is detrimental to growth and performance. Recent research has shown that supplementing protein has the potential to enhance growth performance in weaned steers. Therefore, the objective of this study was to evaluate the effect of supplemental CP on physiological parameters in stocker steers experiencing fescue toxicosis. Thirty-six weaned Angus steers (6 mo of age) stratified by weight (196.1 ...[more]

PMID: 31359059

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Project description:Fescue toxicosis is a multifaceted syndrome common in cattle grazing endophyte-infected tall fescue that affects performance; however, little information is available pertaining to its effects on immunity. Recently, it has been shown that supplemental CP can improve performance in weaned steers postvaccination. Thus, the objective of this study was to evaluate the effect of supplemental CP on innate and adaptive immune responses in stocker steers chronically exposed to ergovaline. Angus steers (n = 12 pens; 3 steers/pen) were stratified by weight and assigned to a 2 × 2 factorial arrangement to examine crude protein levels of supplement (14% or 18%) and ergovaline exposure (0 or 185 ?g ergovaline/kg BW/d via ground endophyte-free (EF) or endophyte-infected (EI) tall fescue seed, respectively) on immune response. Consumption of low to moderate concentration of ergovaline from EI tall fescue seed was sufficient to induce mild symptoms associated with fescue toxicosis. Blood samples were collected at day 0, 42, and 56 to evaluate infectious bovine rhinotracheitis (IBR) and bovine viral diarrhea virus (BVDV) type 1b titers following vaccine challenge. Additionally, serum cytokine concentrations were evaluated using Quantibody Bovine Cytokine Arrays on day 0, 28, and 42. Data were analyzed using PROC MIXED of SAS with repeated measures. Regardless of treatment, no differences were observed in IBR and BVDV-1b seroconversion following vaccine challenge (P > 0.05). Regardless of crude protein concentration, EI steers had greater concentrations of proinflammatory cytokines (TNF-?, IFN-?, IL-1?), chemokines (CCL2, CCL4, MIG), anti-inflammatory cytokines (IL-2, -13, -15, -21), and various growth factors (FGF-1, IGF-1, VEGF-A) when compared to EF steers (P < 0.05). Furthermore, VEGF-A and IGF-1 concentrations were greater in EI-14 steers on day 28 compared to EI-18, EF-14, and EF-18 steers (P < 0.05), however, this difference was not observed on day 0 or 42 (P > 0.05). Based on these data, steers exposed to ergovaline have an increase in pro- and anti-inflammatory cytokines and supplemental CP had minimal impact to mitigate this response. However, in the current study, exposure to ergovaline had little to no effect on adaptive immunity and response to vaccination. Together, chronic exposure to ergovaline results in a hyperactive innate immune response, which may lead to an immuno-compromised animal.

Project description:Consumption of ergot alkaloid-containing tall fescue grass impairs several metabolic, vascular, growth, and reproductive processes in cattle, collectively producing a clinical condition known as "fescue toxicosis." Despite the apparent association between pituitary function and these physiological parameters, including depressed serum prolactin; no reports describe the effect of fescue toxicosis on pituitary genomic expression profiles. To identify candidate regulatory mechanisms, we compared the global and selected targeted mRNA expression patterns of pituitaries collected from beef steers that had been randomly assigned to undergo summer-long grazing (89 to 105 d) of a high-toxic endophyte-infected tall fescue pasture (HE; 0.746 ?g/g ergot alkaloids; 5.7 ha; n = 10; BW = 267 ± 14.5 kg) or a low-toxic endophyte tall fescue-mixed pasture (LE; 0.023 ?g/g ergot alkaloids; 5.7 ha; n = 9; BW = 266 ± 10.9 kg). As previously reported, in the HE steers, serum prolactin and body weights decreased and a potential for hepatic gluconeogenesis from amino acid-derived carbons increased. In this manuscript, we report that the pituitaries of HE steers had 542 differentially expressed genes (P < 0.001, false discovery rate ? 4.8%), and the pattern of altered gene expression was dependent (P < 0.001) on treatment. Integrated Pathway Analysis revealed that canonical pathways central to prolactin production, secretion, or signaling were affected, in addition to those related to corticotropin-releasing hormone signaling, melanocyte development, and pigmentation signaling. Targeted RT-PCR analysis corroborated these findings, including decreased (P < 0.05) expression of DRD2, PRL, POU1F1, GAL, and VIP and that of POMC and PCSK1, respectively. Canonical pathway analysis identified HE-dependent alteration in signaling of additional pituitary-derived hormones, including growth hormone and GnRH. We conclude that consumption of endophyte-infected tall fescue alters the pituitary transcriptome profiles of steers in a manner consistent with their negatively affected physiological parameters.

Project description:The objective of this study was to quantitatively summarize literature reporting endophyte-infected (Neotyphodium coenophialum) tall fescue (Festuca arundinacea) effects on cattle ADG. This meta-analysis evaluated endophyte infection level, climate, and forage yield using a literature dataset of 138 treatments from 20 articles. Three infection level measurements were tested: endophyte infection as a percentage of infected tillers (E%); ergovaline concentration in ppb ([E]); and total ergot alkaloid concentration ([TEA]). Three types of climate variables were used: base values (temperature, humidity, and relative humidity), climate indices (heat index and temperature-heat index [THI]), and novel climate variables accounting for duration of climate effects. Mixed effect models, weighted by 1/SEM, including a random effect of study were built for each factorial combination of measurement method and climate variable group. Because many studies were missing SEM, two datasets were used: one containing only data with SEM reported and one that also included missing-SEM data. For the complete-SEM dataset (CSD), models were weighted by 1/SEM. In the missing-SEM dataset (MSD) the mean reported 1/SEM was assigned as the weight for all missing SEM treatments. Although 18 initial models were created (2 × 3 × 3 factorial approach), the backward stepwise derivation resulted in models that included only endophyte infection level, suggesting a negative relationship between infection level and ADG. The CSD models predicted ADG to decrease 39 and 33 g/d with each increase of 100 ppb of [TEA] and [E], and by 39 g/d for each increase of 10% E%. In the MSD dataset, predicted ADG decreased by 39 and 33 g/d with each increase of 100 ppb of [TEA] and [E], and by 47 g/d for each increase of 10% E%. All relationships reported had P < 0.05. After visual inspection of the data, piecewise regression was used to identify an infection threshold (IT) of 60 ppb [E] and 11 E%, where the effect of infection level was constant on either side of the IT. The ADG was 40% and 49% greater for infection levels below the IT for [E] and E%, respectively. Across THI values in the analysis, ADG decreases ranged from 11.2% to 45.0% for cattle grazing endophyte-infected tall fescue compared to non-ergot alkaloid endophyte infected tall fescue. Pasture E%, [E], and [TEA] have a negative relationship with ADG in growing cattle, and increasing temperature decreases ADG when infection level is greater than the IT.

Dataset Information

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses.

Publications

Effects of endophyte-infected tall fescue seed and protein supplementation on stocker steers: I. Growth performance and hemodynamic responses.

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