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" Hydration status of endurance horses as affected by dietary fiber type with and without supplemental fat "
Holly Sue Spooner
B. D. S. Nielsen, Harold, II
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Latin Dissertation
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English
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| Record Number
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54877
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| Doc. No
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TL24831
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| Call number
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3348222
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| Main Entry
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Holly Sue Spooner
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| Title & Author
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Hydration status of endurance horses as affected by dietary fiber type with and without supplemental fat\ Holly Sue Spooner
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| College
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Michigan State University
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| Date
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2008
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| Degree
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Ph.D.
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2008
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| Page No
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224
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| Abstract
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Water and electrolyte loss from prolonged endurance exercise may result in physiological disturbances in the horse. The large intestine has been suggested to serve as a water reservoir and may help attenuate dehydration. Dietary constituents may affect the amount of water held within the intestine and available for use by the horse. Our initial study examined the hydration status of horses fed three dietary fiber types and subjected to a 60-km exercise test. After an initial training period and preliminary exercise test, horses were assigned to a replicated 3 x 3 Latin Square experiment. Diets were grass hay (G), 50:50 grass hay: alfalfa hay (GA), and 50:50 grass hay: proprietary chopped fiber mix (GM). Total body water (TBW) tended to be higher (p < 0.08) in horses consuming GA and GM than G (65.8 ± 0.8, 65.4 ± 0.8, and 63.9 ± 0.8%, respectively). Body mass (BM) due to diet was not different at the start of the exercise test, but when corrected for fecal loss and water intake showed a trend for diet difference during exercise (p = 0.08), decreasing more in GM than G (5.1 ± 0.4% vs. 3.4 ± 0.4%; GA 4.2 ± 0.4%). Heart rate was not different except at the end of bout one when the heart rate of GM was lower than G or GA (p < 0.01). Core body temperature, although not different at the start of the exercise test bout, was lower (p < 0.05) at the canter in horses consuming GM. Results suggest higher TBW in the GM diet at the initiation of exercise may have provided the horses with a greater "pool" of available water for increased thermoregulation via sweating, allowing maintenance of a lower core body temperature during exercise but at the expense of increased BM loss. However, because the GM diet was higher in fat content, the increase in fat intake may have been responsible for the difference observed, thus meriting further investigation. Our second study was designed to examine the effect of dietary fiber type on hydration status, with and without fat supplementation. In a split-plot design, six two-year-old Arabian horses were randomly assigned to diets containing either chopped grass hay (G) or a chopped grass hay: soluble fiber mix (GM) and either fat supplementation (Ft) or no fat supplementation (NFt). All horses consumed each diet for a period of at least 21 d before completing a 60-km exercise test. Total body water, as determined using D 2 O, was 66.1% of body mass and did not differ due to treatment. Horses consuming GM had greater (p < 0.05) body mass at the start of exercise than those consuming G. Water consumption during the exercise test was greater in G than GM (p < 0.01; 13.3 1.3 L, 10.9 ± 1.3 L), as were PCV (p < 0.01; G 36.8 ± 1.2, GM 35.1± 1.2) and plasma aldosterone across all times (p < 0.001; GM 28.4 ± 3.8 pg/ml, G 53.3 ± 3.8 pg/ml). The results suggest that fiber type plays a greater role in hydration status than does fat supplementation. However, in comparison to a previous study, a higher TBW and lower core body temperature during exercise in this study may suggest that the chopped nature of the fiber may benefit the animal and thus may merit further investigation.
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| Subject
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Biological sciences; Hydration; Endurance horses; Dietary fiber; Supplemental fat; Animal sciences; Veterinary services; 0778:Veterinary services; 0475:Animal sciences
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| Added Entry
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B. D. S. Nielsen, Harold, II
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Michigan State University
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