Browsing by Author "Taylor, Lynn Elizabeth"

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    Acid-base regulation during sprint exercise in horses fed lecithin
    Taylor, Lynn Elizabeth (Virginia Tech, 1995)
    The effects of exercise, training, and a supplemental lecithin/corn oil diet on acid-base homeostasis and blood gases in arterial and central venous blood were examined during repeated sprint exercise in horses. Differences between temperature measurement sites for the adjustment of pH and blood gases during exercise was also investigated. The independent variables, strong ion difference (SID), total weak electrolytes ([Atot]), and pCO₂, had different effects on the dependent variables, [H⁺] and [HCO₃⁻], and these influences changed depending on blood sampling site (arterial or central venous), and exercise intensity. Data supporting the involvement of the chloride shift during repeated sprint exercise in the horse was observed for the first time. Training resulted in increased plasma [Na⁺], [K⁺], [SID], albumin, free fatty acids, and beta~-hydroxybutyrate concentrations, and decreased blood lactate ([Lac⁻]), plasma [Cl⁻], [H⁺], cholesterol, and heart rate during exercise. Horses consuming the corn oil/lecithin supplemented diet had a higher pvCO₂, [HCO₃⁻], [Cl⁻], cholesterol, and glucose, and lower blood [Lac⁻], [H⁺], and triglycerides during exercise. The sprint training and corn oil/lecithin diet may act synergistically to enhance performance in horses’ by maintaining a lower [H⁺] during high intensity exercise. There were differences between skin, rectal, blood, and muscle temperatures during incremental exercise and recovery in horses. The pH and blood gases adjusted to rectal, blood, and muscle temperatures were also different during exercise and recovery. Muscle and blood temperature may be predicted from rectal or skin temperature during exercise, and from skin temperature during recovery.
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    The effects of added fat on acid-base status in exercising horses
    Taylor, Lynn Elizabeth (Virginia Tech, 1991)
    Two groups of horses were each fed either a control diet of ground hay and concentrates (4 horses), or a Similar diet with 10% added fat after undergoing a baseline Standard Exercise Test (SET). The SET was a stepwise, incremental test to exhaustion on an equine treadmill set at a 6% slope. Resting and working heartrates and rectal temperatures were monitored, and venous blood was collected at rest, and every 3 minutes during exercise, just prior to each speed change. Blood was analyzed for pH, hemoglobin, and pCO₂, and base excess and plasma bicarbonate levels were calculated using nomogram equations. Plasma samples were analyzed for albumin at each step, and for sodium, potassium, chloride, and lactate at rest and exhaustion only. The plasma SID was calculated at rest and exhaustion by the following equation: ([Na⁺] + [K⁺]) - ([Cl⁻] + [Lactate]) The SET was performed after 16 days of interval training, and once more after another 16 days of interval training. Differences over time during exercise were found: heartrate, lactate, and potassium increased (p<.001), and hemoglobin increased (P<.01). Decreases were found in PH, pCO₂, bicarbonate concentration, base excess, and chloride (p<.001). Training effects were found in resting and working heartrates, pCO₂, bicarbonate concentration, and base excess, which all decreased during exercise with training. Hemoglobin increased during exercise with training. There were treatment * SET interactions for Strong Ion Difference, base excess, lactate concentration, pCO₂, and pH. There were no differences found between groups for any of the variables measured. Both groups showed improvements in fitness with training, and the fat group had a higher level of plasma lactate by SET 3. These results suggest that a high fat diet combined with interval training may have some effects on plasma lactate, and that training alone can affect many variables. The results also give evidence to support the evaluation of SID during exercise in horses.