Faecal Water Loss Research Articles

Osmoregulation and water balance in the springhare (Pedetes capensis).

Springhares are large rodents that live in arid and semi-arid regions of Africa. We deprived springhares of water for periods of up to 7 days to determine what physiological adaptations. If any, enable them to survive in and regions without drinking. During water deprivation, springhares lost up to 30% body weight and produced a mean maximum urine concentration of 2548 mosmol kg-1 with a maximum of 3076 mosmol kg-1 in an individual animal. Haematocrit and plasma sodium and potassium concentrations were well regulated throughout water deprivation at 47.5 +/- 3.8% and 132.6 +/- 7.4 mmol l-1 and 3.5 +/- 0.7 mmol l-1, respectively, while plasma osmolality increased slightly from 293 +/- 12.5 mosmol kg-1 to 324 +/- 7.3 mosmol kg-1. Springhares thus appeared to be good osmoregulators and were able to maintain plasma volume during 7 days of water deprivation. In addition to the production of a relatively concentrated urine, water loss was limited by the lowered solute load and faecal water loss achieved by a reduction in food consumption and by the production of very dry faeces. These abilities, together with a favourable burrow microclimate and nocturnal activity pattern, enable them to survive in arid regions.

Induced diarrhoea in horses part 1: Fluid and electrolytebalance

Sodium, potassium and water balance, and measurements of acid-base status, haematocrit, packed cell volume and plasma total protein, were studied in four adult standardbred geldings following castor oil induced diarrhoea. Castor oil (2 mL kg-1) administration resulted in signs consistent with mild to moderate acute colitis. The total (combined faecal and urinary losses) losses of sodium and potassium ions were 2169 and 2864 mmol, respectively. Faeces constituted the major route for sodium loss, while urine was the major route for potassium loss at all times. Faecal dry matter potassium concentration did not vary significantly at any stage. Faecal dry matter sodium concentration increased significantly, coinciding with the onset of clinical diarrhoea. Faecal water loss increased significantly from 2.15 +/- 0.44 mL kg-1 h-1 to 5.15 +/- 0.92 mL kg-1 h-1 while clinical diarrhoea was observed. While plasma volume (PV) did not vary significantly in this study, there was a trend for PV to decrease while horses were clinically dehydrated.

Effects of experimental infection with Eimeria bovis on the balance of sodium, potassium and water in calves

Balance trials were performed to investigate the effects of experimental Eimeria bovis coccidiosis on the metabolism of water, sodium and potassium in calves. Non-infected pair-fed controls and controls fed according to plan were included in the study to allow differentiation between the effects due to infection and due to changes in feed intake. Primary infection with 5 × 10 4 (group A) or 1 × 10 5 (group B) oocysts caused mild diarrhoea in three out of four group A calves and mild to severe haemorrhagic diarrhoea in all five group B calves. Losses of sodium and potassium via faeces tended to increase in the infected calves during patency and apparent digestibility ( AD) of these minerals was comparably low. In the urine of the infected calves the Na/K-ratio decreased due to a reduced urinary excretion of sodium. The retention ( RT) of sodium was particularly high in the calves that had received the higher oocyst dose. Potassium RT did not underlie significant changes during the course of coccidiosis. In the infected calves the plasma level of sodium was reduced transiently while the level of potassium remained fairly stable. Infections with the higher oocyst dose caused a distinct reduction of fluid excretion via urine which compensated for the increased faecal water losses during severe diarrhoea. Reinfection of the group A calves with 1 × 10 5 oocysts did not cause any significant metabolic impairment. The results of this study indicate that although acute sublethal bovine coccidiosis alters electrolyte and water metabolism the overall balance of electrolytes and water is largely maintained by physiologic adaptation.

Fecal short-chain fatty acids associated with inflammation in cotton-top tamarin model for idiopathic colitis.

This study measured fecal levels of short-chain fatty acids (SCFAs) relative to the severity of colitis in the cotton-top tamarin model of colitis and colon cancer. Severity of colitis was classified as mild, moderate, or severe by subjective scoring of colonic mucosal biopsies and quantification of inflammatory cell infiltrates in the lamina propria. SCFAs were determined by gas chromatography of SCFAs extracted from fresh feces. Tamarins with moderate or severe colitis had significantly reduced levels of fecal SCFAs. The percent dry matter of feces declined significantly in moderate and severe colitis, while total dry matter output per day increased, indicating that moderate and severe colitis in tamarins was associated with diarrhea and increased fecal water loss. In conclusion, this study found colitis in the tamarin model was associated with decreased fecal SCFA levels and progressive inflammation in a pattern similar to human colitis.

Effects of restriction of water and food intake on thermoregulation, food utilization and water economy in desert sheep

Adult desert rams were used to evaluate the effects of water restriction (46% ad libitum level) and food restriction (32% ad libitum level). Rectal temperature was reduced by food restriction, and respiration rate was reduced both by water and by food restriction. Water restriction decreased dry matter intake (g kg −0.75 ) and food restriction decreased water intake (ml kg −1 ). With both water and food restriction, water turnover rate (ml kg −1 ), faecal and evaporative water losses decreased. Urine volume decreased only with water restriction. Restriction of water and food intake decreased nitrogen loss in faeces and urine, whereas retained nitrogen decreased with food restriction only. Both plasma and rumen fluid osmolality increased with water restriction, but decreased with food restriction. The rumen pH increased with food restriction but decreased with water restriction. With food restriction, rumen NH 3 increased and the concentration of volatile fatty acids decreased. Plasma glucose level decreased in response both to water and to food restriction, whereas plasma urea concentration increased only with water restricion.

Post‐prandial urine loss and its relation to ecology in brown long‐eared (Plecotus auritus) and Daubenton's (Myotis daubentoni) bats (Chiroptera: Vespertilionidae)

Urine loss, over the first 12 hours after feeding, was positively and linearly dependent on food consumption in water‐denied, brown long‐eared bats (Plecotus auritus) and also in water‐denied and water‐provided, Daubenton's bats (Myotis daubentoni). The slope of the relationship (food‐dependent urine loss) (363 μ 1 g dry mass food−1, S.D.=±70, n=19) was not significantly different between the two species but predicted urine loss at zero food consumption (food‐independent urine loss) was significantly lower in P. auritus (0.048 μl.min−1, S.D. =±0.015, n= 12) than in M. duubentoni (0.217 μl min−1 S.D. =±0.040, n = 7). The same results were apparent if the data for M. daubentoni were restricted to water‐deprived animals only. Of total urine loss, 46% occurred in the first hour after feeding in M. daubentoni compared with only 20% in P. auritus. We suggest that the differences between the two species in the pattern of postprandial urine loss reflect their relative association with open water when foraging and roosting in the wild. In the course of the water‐denied experiment, M. duubentoni lost 15% of pre‐fed body mass and showed signs of severe dehydration, while P. auritus only lost 6% and did not. However, urine loss only accounted for 8–10% of body mass loss. A water budget model for wild P. auritus in the summer was developed and suggested that if bats did not drink, approximately 19% of water loss would be attributable to faecal water loss, 18–20% to urine loss, and 59–62% of intake would be available to support evaporation and reproductive losses.

Water economy and body fluid distribution in the hamadryas baboon ( Papio hamadryas)

1. 1.|Water economy and body fluid distribution in hamadryas baboons were studied in outdoor enclosures during the summer (22–32°C). 2. 2.|Following 2 days of water deprivation the baboons' lost 10% of body mass. 3. 3.|Following water deprivation, sweating, fecal and urinary water losses were greatly reduced. 4. 4.|After water deprivation, blood plasma volume dropped by only 4% of their initial volume. 5. 5.|Maintenance of blood plasma volume is interpreted as an adaptation to life in xerotic habitat.

Effects of water restriction on digestive function in two macropodid marsupials from divergent habitats and the feral goat.

The effects of water restriction on digestive function in the euro (Macropus robustus erubescens) found in the arid zone of inland Australia, the eastern wallaroo (M.r.robustus) from more mesic regions of eastern Australia, and the feral goat (Capra hircus) found throughout the range of M. robustus, were compared in order to examine some physiological adaptations required by herbivores for the exploitation of arid environments. Eight animals of each species were held in individual metabolism cages in temperature-moderated rooms and given a chopped hay diet ad libitum. Half the animals were restricted to 40 ml water.kg-0.80.day-1. This was 40%, 32% and 57% of voluntary drinking water intake in the euro, wallaroo and goat, respectively. All species responded to water restriction by reducing faecal, urinary and evaporative water losses in association with reductions in feed intake. All animals increased urine osmolality and electrolyte concentrations but not to maximal levels, while packed-cell volume and plasma osmolality and electrolyte concentrations were unaffected by water restriction. The euro displayed a suite of characteristics that separated it from the wallaroo in terms of physiological adaptation, including lower voluntary water intake, an increase in fibre digestibility and maintenance of nitrogen balance during water restriction, and lower faecal water efflux associated with a consistently lower faecal water content (54% versus 59% water in the wallaroo during water restriction, P < 0.05). The euro's colon was 37% longer (P < 0.01) than that of the wallaroo. The goat had the lowest faecal water efflux (P < 0.05) and the longest colon (P < 0.001). Water restriction did not affect water content in digesta, nor short-chain fatty acid concentrations or production rates in vitro. Total body water, as a proportion of body mass, was depressed (P < 0.05) in the macropodids, but not in the goat. The reduction in dietary nitrogen intake, which accompanied water restriction, was partially compensated by an increase in urea degradation in the gut from 68% to 76% of urea synthesis water-restricted macropodids. These responses to water restriction are discussed in relation to those reported in other macropodid and ruminant species.

Dimensions of the intestine, diet and faecal water loss in some African antelope

Measurements of the intestine of 16 species of antelope were allometrically analysed. Moisture content of the digesta showed greatest interspecific variation in the spiral and distal colon. Small intestine length showed positive allometry, its circumference showed negative allometry, resulting in a surface area which was isometric or related to metabolic rate. Dimensions of the villi were non‐allometric. Grazers had lower surface areas of the small intestine than intermediates/concentrate selectors owing to smaller circumferences. In the large intestine, the dimensions of the distal colon showed the greatest interspecific variation. Lengths of the large intestine showed positive allometry except for the caecum which was isometric. Circumferences and areas of the large intestine were isometric or related to metabolic rate. Species producing dry dung had larger lengths and areas of the large intestine but a smaller circumference of the proximal and spiral colon and also showed greater drying of digesta per unit area than those producing wetter dung. Grazers had smaller lengths, circumferences and areas of the large intestine than intermediates/concentrate selectors.

Effects of Restricted Water-Intake on Digestion, Urea Recycling and Renal-Function in Wombats (Marsupialia, Vombatidae) From Contrasting Habitats

Responses to limited water availability were studied in two species of wombats from mesic (Vombatus ursinus) or xeric (Lasiorhinus latifrons) habitats. Four Vombatus and three Lasiorhinus were fed a low-quality straw-based diet containing 0.6% nitrogen and 68% neutral detergent fibre (dry-matter basis). Restriction to 50% of ad libitum intakes of drinking water reduced dry-matter intakes by 30% but did not alter digestibilities of fibre or nitrogen. Nitrogen balances were negative and similar between species and water intakes. Urea pool size (C-14 urea) increased during water restriction but urea-entry rates and the proportion of urea recycled to the gut were similar between water intakes (78-89%). Tritiated water was given to wombats in single intramuscular or intraperitoneal doses. Times to equilibration of tritium in urinary water were large and variable (45 +/- 36 h). Urinary tritium concentrations often declined erratically after equilibration, and were 14 +/- 14% lower than the tritium concentration in the blood. These irregular kinetics for tritiated water suggest that the water-dilution method requires validation for the wombats. Urinary and faecal water losses were reduced by 60% during water restriction. Water was mainly lost in the faeces, which were drier in Lasiorhinus (41 % dry matter) than in Vombatus (31 %). As blood haematocrit and plasma osmolality were similar between water intakes, extracellular spaces were apparently maintained during water restriction. Glomerular filtration rates (creatinine clearance) were low (12 mL min-1) and similar between water intakes. Therefore, a more concentrated urine was produced by tubular resorption in water-restricted wombats. Lasiorhinus had greater urinary osmolalities and urine: plasma ratios of creatinine, which reflected a greater urine-concentrating ability than Vombatus. Apparent water intakes and the ability to reduce urinary and faecal water losses in the wombats are similar to those of kangaroos. The contrasting abilities of Vombatus and Lasiorhinus to minimise both these water losses are directly related to their separate distributions.

Differences between sheep excreting sodium predominantly in their urine or in their faeces: the effect of changes in sodium intake

Sheep receiving a total of about 31 mmol day-1 (0.5 mmol kg-1) of sodium were classified according to the predominant route of sodium excretion; urinary (U) or faecal (F). U sheep had a greater water turnover than F sheep; their intake was 41% higher and they produced 133% more urine but there was little difference in faecal water loss. Most faecal sodium was readily exchangeable with water in both groups. When sodium intake was reduced by 80% (to 6 mmol day-1; 0.1 mmol kg-1), the reduction in total sodium excretion was equally effective in F sheep and U sheep after 48 h and after 2 weeks the overall losses of sodium were smaller in F sheep. On sodium intakes close to requirement (0.1 mmol kg-1 or less) the majority of the sheep excreted most of their sodium in faeces and did so on intakes up to 0.5 mmol kg-1 day-1. Excess dietary sodium is mainly excreted renally. When sodium intake is increased abruptly (by 20 mmol day-1, 0.3 mmol kg-1), total sodium excretion only increases gradually but after about 3 days it 'overshoots' as in humans.

Daily biphasic behaviour in keratin‐feeding desert trogid beetles in relation to climate

Abstract. 1. Patterns of daily activity of two ectothermic species of the trogid genus Omorgus were studied in the Kalahari of southern Africa in summer. The relationship between time and type of activity, and environmental temperature, relative humidity and light intensity, was investigated.2. Beetle activity was biphasic, with peaks in activity at sunset and sunrise in both species.3. Afternoon activity coincided with high temperatures and low humidity and morning activity with minimum daily temperature and maximum humidity.4. Afternoon activity, which peaked at about 34°C and 25% r.h., consisted predominantly of complex breeding behaviour and dispersal. High temperatures are necessary for these activities.5. In the morning feeding predominated. At this time temperature was about 27°C and r.h. above 60%. High r.h. is important because it restricts respiratory loss of water, improves food (moist hair and skin keratin) quality and may compensate for faecal water loss.6. No evidence of competition between the two species was found.

Adaptations to a Terrestrial Existence by the Robber Crab Birgus Latro: VI. The Role of the Excretory System in Fluid Balance

ABSTRACT Primary urine is formed by filtration in the antennal organ of Birgus latro L. Urine isosmotic with the haemolymph is released into the anterior branchial chambers where substantial reabsorption of water and ions may occur. Some of the branchial fluid is ingested and the remainder (final excretory fluid, P) is released. Crabs supplied with fresh water have a low drinking rate (1.82ml 100g−1 day−1). Primary urine is partially reabsorbed (27%) in the antennal organ and urine flow (4.48 ml 100 g−1 day−1) is significantly lower than filtration rate (5.77ml 100g−1 day−1). The volume of P released is small in crabs drinking fresh water (0.45 ml 100 g−1 day−1) and the fluid is dilute (≈25mmoll−1 NaCl). The difference between P flow and drinking rate (1.37ml 100 g−1 day−1) represents evaporative and faecal water losses. Provision of saline drinking water (300, 600 or 1000mosmolkg−1 sea water) doubles rates of drinking, filtration and urine flow and increases P flow fourfold. Evaporative/faecal water loss remains constant. Reabsorption of salts from the P rapidly decreases when saline media are provided for drinking.

The ship of the desert. The dromedary camel (Camelus dromedarius), a domesticated animal species well adapted to extreme conditions of aridness and heat

The dromedary camel (Camel dromedarius) is extremely well adapted to life in hot and arid lands. In terms of physiological adaptation to heat and water deprivation it surpasses by far every other large animal of which data have been collected. None of the adaptive mechanisms to cope with the environmental stresses are unique to the Arabian camel, but the efficiency of its adaptation is superior. At high ambient temperatures the camels adapt to the scarcity of water by reducing their faecal, urinary and evaporative water losses. During dehydration, the kidneys reduce water losses both by decreasing the glomerual filtration rate and by increasing the tubular reabsorption of water. Also their ability of regulating their body temperature from 34.5-40.7 &amp;deg;C conserves a lot of water, when most needed.

Large Colon Resection

With large colon resection and anastomosis, up to 95 per cent of the length of the large colon has been successfully removed. A hand-sewn end-to-end anastomosis is effective for lesions in the left dorsal colon and pelvic flexure. Transection and a side-to-side anastomosis with stapling equipment is most effective for extensive resections (greater than 50 per cent). Horses with extensive colon resection (95 per cent) have permanent deficiencies of water absorption and digestion of cellulose and protein. Fermentative capacity is reduced, owing to decreased particulate matter retention time in the smaller capacity colon. These deficits are minimized with alfalfa hay as the source of forage (fed at 2 per cent of the body weight), and normal blood variables and body weight can be maintained. Voluntary intake increases to help maintain a positive nutrient balance. Grass hay, owing to the higher cell wall content, is inadequate as the sole source of energy and protein, and weight loss will occur. Ad libitum intake of water is recommended at all times, owing to the increased fecal water loss.

The effect of pregnancy and sodium intake on water and electrolyte balance in sheep

Sodium, potassium and water balance were studied throughout pregnancy in sheep on diets providing 1 mmol/kg body weight/d (H) or 0·1 mmol/kg body weight/d (L) of sodium, as well as non-pregnant controls. The polydipsia of pregnancy preceded the polyuria and the latter was greater in twin pregnancies. Faecal water loss also increased. Water turnover was particularly high in sheep excreting the majority of their sodium in urine rather than faeces; they also had greater total sodium loss at the end of pregnancy on the L diet. Sodium conservation was sustained throughout pregnancy on L diets but on H diets the increased output of urine and faeces led to increased sodium losses beyond day 90. Aldosterone secretion rose to a peak around day 100 in L sheep but was suppressed throughout pregnancy in H sheep, suggesting that this level of intake was well above requirement. The results are discussed in relation to the fluid and electrolyte physiology of pregnancy and the dietary sodium requirement.

Stool water in preterm neonates.

Data are presented on faecal water losses in 93 preterm infants being fed breast milk (72 infant days) or formula (280 days). Losses per kg increased to 4 weeks, when they amounted to 11% of water requirement in infants fed breast milk and 8% in infants fed formula.

The effect of relative humidity on osmoregulation in the squirrel monkey (Saimiri sciureus)

Osmoregulatory balance was studied in four young, tamed squirrel monkeys (Saimiri sciureus, Columbia) after acclimatization to relative humidities (rh) commonly used in laboratories (30% and 50%) and to higher humidities representative of the dry and wet seasons in their natural environment (75% and 95%). The temperature was constant at 25°C and the light-dark cycle was 12:12 hours. The animals were maintained in large metabolism cages and were free moving. Water consumption and urine flow rates increased at each higher humidity from 30% rh to 75% rh and then decreased at 95% rh (p<0.05). Fecal water loss was greater with higher humidity (p<0.05). Evaporative water loss remained relatively constant until a break between 75% and 95% rh, at which point it decreased dramatically (p<0.05). Expressed relative to total water intake, evaporative water loss demonstrated a progressive decrease with increasing humidity: 65%, 56%, 51%, and 42%, at 30%, 50%, 75%, and 95% rh. This indicates that as the humidity approaches maximum saturation, not only is the evaporative water loss component necessarily diminished, but also the apparent precipitation of alternate strategies of thermoregulation leads to a reduction in the overall water requirements of the animals. Potassium/sodium excretion ratios were relatively constant at 30%, 50%, and 95% rh but decreased significantly at 75% rh (p<0.05). As a reflection of adrenocorticosteroid activity, this suggests that at 25°C, 75% rh is an optimal humidity in the maintenance of squirrel monkeys. The significant osmoregulatory alteration occurring between 75% and 95% rh provides further evidence that relative humidity may be an important factor in the seasonal physiological cycles of the squirrel monkey.

The effect of a high fibre diet on energy and water balance in two Namib desert rodents

The effect of dietary fibre content on food consumption, digestive ability and water balance was studied in two Namib desert rodents,Aethomys namaquensis andGerbillurus paeba. In addition, changes in these factors were monitored when free water was withheld. 1. Daily energy expenditure (DEE) forA. namaquensis remained fairly constant and similar to that predicted by mass despite changes in food and water regimes. The DEE inG. paeba was more variable. On a millet (low-fibre) diet with ad lib. water DEE was 35% higher than the expected value. This increased still further within the first week of water deprivation before dropping back to pre-water deprivational levels once mass had stabilized. On the high fibre diet, the DEE ofG. paeba was similar to that predicted by mass when water was freely available. This was reduced by half when the animals were water stressed, suggesting thatG. paeba might employ torpor under these circumstances. 2. Water balance was assessed by measuring water intake and loss. Faecal water content when maintained on a millet diet was similar in both species, irrespective of whether water was freely available or withheld. However, urine concentrations and estimated evaporative water losses were higher inG. paeba. Observed differences in water loss are largely a function of variables related to weight specific metabolic rate. Differential water losses were offset by differences in metabolic water production, enabling both species to attain a positive water balance and survive indefinitely on a millet diet. 3. When provided with a more fibrous diet, low assimilation efficiency and the resulting increase in faecal production, coupled with increased faecal water content, increased faecal water loss to such an extent that it precluded the maintenance of a positive water balance in either species. Despite increased urine concentration and a decline in evaporative water loss, both species rapidly succumbed to chronic water deprivation.

Energy and water balance during torpor and hydropenia in the pigmy gerbil,Gerbillus pusillus

Under ad lib. food conditions,G. pusillus used 107% of the predicted daily energy expenditure. This increased significantly with water deprivation to 116% of the allometric expected value, thereby reflecting an increase in activity in search of food with high moisture content, a shift to metabolic water for meeting the animal's water requirements and a change in the state of hydration of the animal. Economic water expenditure through efficient kidney concentrating ability, reduced pulmocutaneous evaporation, reduced faecal water loss, and tolerance to haemoconcentration, was sufficient to impart virtual independence of exogenous water. Gerbillus pusillus responded to food shortage by abandoning homeothermy. In doing so, it was able to maintain a fairly stable body mass by monitoring energy intake and ensuring that energy expenditure did not exceed intake. There was no significant difference in energy expenditure between gerbils on a restricted energy intake and ad lib. water and those gerbils on a restricted energy intake and no water. Both these experimental groups were able to maintain a positive water balance, for whilst less metabolic water was available, water loss primarily through evaporation decreased concomittantly with reduced body temperature. In addition, the volume of urine excreted when torpid accounted for approximately 5% of the volume excreted by coenothermic rodents deprived of free water. Urine, although less concentrated than that of non-torpid gerbils deprived of water, was ten times more concentrated than the plasma. Daily torpor, although uniquely suited to energy conservation, is not without cost. A reduced body temperature resulted in a decline in ‘apparent assimilation efficiency’ (AE). It seems therefore that the cost of maintaining an elevated body temperature for the full duration of digestion is impractical. The cost of employing torpor as calculated from the reduced AE of food (0.5 kJ·day−1), was however insignificant in comparison to the savings accured (32.25 kJ·day−1) by the use of torpor.