Browsing by Subject "Equine"

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    Advances in Horse Nutrition and Muscle Protein Synthesis: Grazing Warm Season Annual Forages and Evaluating Muscle Protein Synthesis in Response to Leucine
    (2016-08) DeBoer, Michelle
    Warm-season grasses have the potential to provide forage in Upper Midwest pastures. The objectives of this research were to determine yield, forage nutritive value and preference of annual warm-season grasses under horse grazing. Four adult horses (Equus caballus) grazed Japanese millet (Echinochloa esculenta (A. Braun) H. Sholz) Siberian millet (Setaria italica (L.) P. Beauv.), teff (Eragrostis tef (Zucc.) Trotter) sorghum sudan BMR (Sorghum bicolor (L.) Moench), sudangrass (Sorghum sudanense (Piper) Stapf.), and annual ryegrass (Lolium multiflorum L.) at mature and vegetative stages. Forages were seeded in two separate plots utilizing a randomized complete block design with three replicates per plot. Each plot was grazed at a distinct target maturity and each maturity was grazed a minimum of three times each grazing season over a two-year period. Sudangrass was consistently the highest yielding grass (P ≤ 0.0002), producing ≥ 5.5 MT ha-1 at the vegetative stage and ≥ 9.7 MT ha-1 at the mature stage while Japanese and Siberian millet exhibit the lowest yields at ≤ 5.5 MT ha-1 at the vegetative stage and ≤ 6.3 MT ha-1 at the mature stage. Annual ryegrass was the most preferred grass (P ≤ 0.0057) with ≥ 60% removal at the vegetative stage and ≥ 40% removal at the mature stage. Siberian millet was the least preferred grass with ≤ 40% removal at the vegetative stage and ≤ 5% removal at the mature stage. While warm-season grasses meet the nutritional requirements of many classes of horses, Ca:P under 1:1 was observed as well as high NO3-N levels. These conditions could lead to limited mineral availability and possible nitrate toxicity. While teff and sudangrass have potential to be grazed by horses, Ca:P and NO3-N levels should be determined before grazing. Limited research is available regarding the role of leucine in regulating equine skeletal muscle protein synthesis. The objective of this study was to evaluate the effect of leucine on protein synthesis in cultured equine satellite cells by evaluating translation initiation factors in a western blot, the incorporation of puromycin using a nonradioactive surface sensing of translation (SUnSET) method, and measuring the incorporation of [3H]Phenylalanine (3HPhe) in a protein synthesis assay. Satellite cells from equine semimembranosus muscle were grown in cell culture until they developed into myotubes. Treatments used in the western blot consisted of a no leucine control (CON), leucine (LEU), control plus rapamycin (CR), and leucine plus rapamycin (LR). LEU exhibited higher 4E-BP1 and rpS6 phosphorylation when compared to CON with no change observed in mTOR phosphorylation. No increase in phosphorylation was observed in CR or LR treatments. Puromycin incorporation was measured on treatments including a no puromycin control, a no leucine control (CON), and a leucine treatment (LEU). These results showed a 1.6-fold increase in puromycin incorporation between CON and LEU (P = 0.0004). Treatments used in the protein synthesis assay consisted of a leucine titration ranging from 0-nm to 408-nm. These results showed muscle protein synthesis rates increased as a result of leucine treatments with significant differences observed at 204-nM and 408-nM leucine compared to the untreated cells. These treatments exhibited a 1.6-fold increase in protein synthesis rates when compared to the untreated control (P ≤ 0.02). This study demonstrated the phosphorylation of translation initiation factors downstream of mTOR as well as increased 3HPhe and puromycin with leucine treatment. These results suggest leucine can trigger muscle protein synthesis in horses through activation of the mTOR pathway.
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    Autologous conditioned serum and subsequent synovial fluid concentrations of cytokines, matrix metalloproteinases, and tissue inhibitors of metalloproteinases after injection into equine osteoarthritic distal interphalangeal joints
    (2015-07) Tatarniuk, Dane
    INTRODUCTION: Autologous conditioned serum (ACS) is used for treatment of osteoarthritis in horses. However, there is a lack of critical knowledge of the contents of ACS and any biological effects after injection into osteoarthritic joints. OBJECTIVE: The specific aims of this study were to (1) evaluate content of cytokine, matrix metalloproteinases (MMP), and tissue inhibitors of matrix metalloproteinases (TIMP) in ACS, (2) validate/refute that ACS increases anti-inflammatory or pro- inflammatory biomarkers in synovial fluid from naturally occurring osteoarthritic joints, (3) demonstrate whether freeze/thaw effects IL-1ra concentrations in ACS, and (4) evaluate for clinical improvement in lameness following ACS therapy. METHODS: Eleven horses with naturally occurring osteoarthritis in a forelimb distal inter-phalangeal joint were given 3 consecutive intra-articular doses of ACS separated by 7-day intervals. Synovial fluid was collected before administration of each dose at day 0, 7, 14, and 21. Concentrations of cytokines (IL-1ra, IL-1Beta, TNF�, IL-4, IL-6, IL-8, IL-10), MMPs (-1, -3, -9, -13), and TIMPs (-1, -2, -3, -4) were quantified using ELISA and multiplex assays. Serum was compared to unincubated and incubated controls and synovial fluid was compared to baseline (day 0). Horses were videotaped trotting (at day 0, 7, 14, and 21) and graded blindly for degree of lameness. RESULTS: Concentrations of IL-1ra, as well as MMP-1 to TIMP (-1, -2, -3, -4) and MMP-9 to TIMP (-1, -2, -4) ratios were increased in ACS (vs. unincubated control), and IL-4, IL-6, and IL-8 were decreased in ACS (vs. incubated control). Freeze/thaw did not affect biomarker concentrations in ACS. Although ACS contained high concentrations of IL-1ra, no changes in IL-1ra concentrations were observed in synovial fluid 7 days after each injection. No change in median lameness grade was noted throughout study duration (median grade of 1/5 at all time points).
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    Genetic exploration of exercise associated sudden death in racehorses
    (2024) Stock, Joy
    Background: Exercise-associated sudden death (EASD) is a fatal collapse occurring during or within 2 hours of racing or training in an otherwise healthy individual. It represents a significant cause of mortality in racehorses, accounting for 25% of the approximately 500 annual racehorse fatalities in the United States. Beyond its negative impact on equine welfare, EASD poses risks to jockey safety and challenges the public perception of horse racing. Cardiac-related issues are the cause of approximately 50% of EASD cases. Cardiac arrhythmias are also thought to be an important contributor to the EASD cases without a diagnosis at necropsy. In human patients without a diagnosis at necropsy, ion channelopathies are found to be an important underlying cause. The genetics underlying EASD have been largely unexplored in horses.Hypothesis: Thoroughbred racehorses with variants in ion channels and other arrhythmogenic genes are predisposed to a higher risk of EASD. Specific Aim1: This study aimed to identify causative positional candidate regions for EASD in Thoroughbred racehorses. Methods: Whole-genome sequencing (target: 12X coverage) and a Genome-wide Efficient Mixed Model Association (GEMMA) univariate linear mixed model genome-wide association study (GWAS) were performed on 50 EASD cases and 48 controls. Results: We identified 8 significant regions linked to EASD. Although genes in these regions were not directly analogous to known human ion channelopathy genes, aquaporin 4 (AQP4) and potassium channel tetramerization domain containing 1 (KCTD1) on the region in chromosome 8, showed potential relevance to dysrhythmia development. Specific Aim 2: This study aimed to identify causative variants in arrhythmogenic candidate genes for EASD in Thoroughbred racehorses. Methods: Candidate genes were identified using a keyword-based query of four databases: Phenolyzer, ClinVar, Online Mendelian Inheritance of Man, and OpenTargets. From these, a narrow (genes identified in all four programs) and a broad (genes identified in two or three programs) candidate gene set were established. SnpSift CaseControl was used to identify significant differences between EASD cases and controls. Results: We identified a significant modifier variant in troponin T2-cardiac type (TNNT2) from the narrow gene set. The broad gene set analysis identified 39 significant variants across 21 genes, with notable findings in triadin (TRDN) and calcium voltage-gated channel subunit alpha1 D (CACNA1D), both of which are linked to cardiac arrhythmias in people and may contribute to equine EASD. Conclusions: We identified variants and genes that may be contributing to EASD in Thoroughbred racehorses. These variants and genes warrant further investigation for their roles in exercise-induced arrhythmias, sudden death, and EASD in Thoroughbred racehorses.