The effect of dietary fibre on hydration status after dehydration with frusemide

Abstract

Summary Three diets were fed to 6 horses in a 3 × 6 Latin rectangle experiment to determine if dietary fibre could improve hydration status in response to dehydration with frusemide. Frusemide was used to simulate dehydration from exercise‐induced sweat loss. Diets contained similar dry matter (DM), energy, protein and electrolyte content, but differed in total dietary fibre (TDF) and/or soluble fibre (SDF). The 3 diets were: 1) HIGH‐HIGH (high TDF, high SDF); 2) HIGH‐LOW (high TDF, low SDF); and 3) LOW‐LOW (low TDF, low SDF). In each 10 day period, water intake and faecal moisture content were assessed on Day 7. On Day 10, feed and water were withheld and horses were dehydrated with frusemide (1 mg/kg bwt, i.m.). Plasma volume (PV), plasma total protein (TP), packed cell volume (PCV) and plasma electrolyte concentrations were determined before and after frusemide administration. Water consumption was greater (P<.05) when horses received diets high in TDF. Faecal moisture content was greatest (P<.01) when horses received the HIGH‐HIGH diet. The decline in PV and the rise in plasma TP concentration following frusemide administration were similar for all diets. When horses received the HIGH‐HIGH diet, they had a greater (P<.05) bodyweight before dehydration and lost more (P<.05) bodyweight in response to frusemide. A greater loss of bodyweight in response to frusemide without a proportional loss of PV when horses received the HIGH‐HIGH diet suggests that a diet high in SDF may provide the horse with a source of dispensable water in the hind gut during dehydration.

The effect of dietary carbohydrate composition on apparent total tract digestibility, feed mean retention time, nitrogen and water balance in horses

“…The horses drank more water when fed the hay-only diet (HAY) compared with the concentrate diets (BAR + SBP and BAR) in agreement with previous studies where forage-only diets have been compared with mixed rations (Fonnesbeck, 1968;Warren et al, 1999). It has been suggested that the hindgut can act as a fluid reservoir when fibre-based diets are fed (Meyer, 1987), but also that fibre composition might affect water binding and reduce its availability (Cuddeford et al, 1992).…”

“…SBP has been proposed to have other beneficial effects than being a highly fermentable fibre source: for example, improving the water balance in horses (Warren et al, 1999) and having a positive effect on the apparent digestibility of the cell wall fraction when lucerne hay or silage were partly substituted with SBP (Murray et al, 2008). Furthermore, when SBP was included in a diet with barley, caecal pH did not decrease as much after feeding as when the same amount of barley was fed alone (Brøkner et al, 2010).…”

Horse Welfare and Natural Values on Semi-Natural and Extensive Pastures in Finland: Synergies and Trade-Offs

“…The low Cu and Zn (critical for the bone structure) intakes need to be compensated, too, with supplementation to ensure healthy bone formation [37,39]. The K content was typically high in forages [35], and can negatively affect anion-cation and fluid balances in the horses [57].…”

Effect of Restricted Grazing on Hindgut pH and Fluid Balance

“…Water intake is related to roughage intake. Reducing dietary roughage intake results in decreased water intake [17,18]. Second, rapid consumption of pasture occurring when grazing resumes following a period of grazing restriction could alter fluid balance by way of increased alimentary secretions associated with increased feed intake.…”

“…However, the lack of difference in fecal DM would suggest that if there was a change in fluid balance, then it did not chronically impact the hindgut fluid balance. Fecal moisture is influenced by the amount and type of dietary fiber [17]. This is important because large fluctuations in hindgut fluid balance can contribute to impaction colic [4].…”