Body Water Turnover Research Articles

Accuracy of the tritium water dilution method for determining water flux in reindeer (Rangifer tarandus)

The accuracy of the tritium water dilution method in estimating water flux was evaluated in reindeer under various conditions of temperature and diet. Two non-pregnant female reindeer were restrained in metabolism stalls, within controlled-environment chambers, at temperatures of + 10, −5, and −20 °C; varying amounts of a commercial pelleted ration (crude protein, 13%) or mixed lichens (crude protein, 3%) were offered, and water was provided ad libitum either as snow or in liquid form. Total body water volume and water turnover were estimated using tritiated water, and the daily outputs of feces and urine were measured for each of 12 different combinations of diet and temperature. Statistical analysis of the data showed that the tritium water dilution technique gives accurate determinations of total body water flux over a wide range of environmental and nutritional conditions.

Environments of Kangaroo Rats (Dipodomys) and Effects of Environmental Change on Populations in Southern Nevada

Climates and plant components of environments of the heteromyid rodents Dipodomys merriami, D. microps , and D. deserti are characterized and compared on sites over 2600 square kilometers in central-southern Nevada. Sites compared are those with the 20 highest-density populations each of D. merriami and D. microps , and all sites with D. deserti , from among 58 undisturbed communities where rodent numbers were established by five consecutive years of censusing. The study areas were in eight drainage basins of the Nevada Test Site, at elevations of 915 to 1850 meters (m), and included Mojave, Great Basin, and transition desert systems. Other parameters measured on each site, and compared for the site groups, are rainfall, maximum and minimum air temperatures, and various parameters for all plant components of the systems. Plant data were collected seasonally with the rodent data, whereas the climatic data were for 10 years. Distributions of D. merriami and D. deserti were correlated with the low shrub cover and low mean precipitation/mean temperature (P/T) ratios of the Mojave Desert Larrea communities. Distributions and higher densities of D. microps were closely correlated with the high shrub cover and high P /T ratios of the Coleogyne and Grayia-Lycium communities of the transition, and Artemisia of the Great Basin Desert. On the compared sites either D. merriami or D. microps usually occurred to the near exclusion of the other, and none of the plant parameters other than percentage shrub cover distinguished the two rodent environments. Restriction of D. microps to environments with high mean rainfall supports recent physiological evidence by others that this species may have the highest bodywater turnover rate and lowest urine-concentrating ability in the genus. On nine other sites shrub cover had been destroyed (and surface soils modified) by nuclear detonations, fire, or blading prior to the measurements period. Three of the sites were in declining ionizing-radiation fields. Regardless of nature of origin of the disturbance, there was a rapid and usually nearly complete replacement of D. microps by large D. merriami populations following the disturbance. The only change in plant parameters consistent among the sites was the large reduction in shrub cover. Occupancy of these sites by D. merriami was in accord with its ability to live with low shrub cover. Disappearance of D. microps was evidently related to its corresponding requirement of high shrub cover, suggesting a vulnerability to elimination by predators where there are few or no shrubs in the environment.

Seasonal variation in water turnover by oryx and eland on the Galana Game Ranch Research Project

SummaryMeasurement of total body water and water turnover was based on the single injection dilution principal using tritiated water.Under a daylight grazing regime the water turnover varied from 24 to 98 ml/kg/day in oryx and 42 to 121 ml/kg/day in eland. This large seasonal variation was most highly correlated with heat load expressed as solar radiation or mean ambient temperature. Lack of correlation between water turnover and dry matter intake, and low correlation with dietary moisture may have been due to difficulties in measuring these parameters accurately.When preformed water was calculated by subtraction of drinking and metabolic water from total turnover, it was found to have a positive correlation with turnover rate and a negative correlation with water drunk. Thus high water turnover was not associated with high drinking requirements in either species.The relationship between climate, pasture and water turnover, could be upset by changes in the activity of the animal from the normal day grazing pattern.The results obtained from the domestic game animals were used to explain how wild oryx and eland could exploit a hot, semi‐arid environment without drinking. To achieve this, the wild animal must obtain most of its nutritional requirements between evening and morning, and its water requirements during the period of maximum relative humidity between midnight and dawn.

Saline drinking and cloacal excretion of salt and water in the zebra finch.

ARTICLESSaline drinking and cloacal excretion of salt and water in the zebra finchE Skadhauge, and SD BradshawE Skadhauge, and SD BradshawPublished Online:01 Dec 1974https://doi.org/10.1152/ajplegacy.1974.227.6.1263MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByRenal and extrarenal regulation of body fluid compositionRe-evaluating model assumptions suggests that Australian birds are more tolerant of heat and aridity than predicted: a response to Conradie et al . 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Water Stress of Free‐Living Peromyscus Truei

The water relations of a Peromyscus truei population from a xeric environment, chamise chaparral, were studied in the field during two periods, midsummer and late summer, and in the laboratory. Animals were maintained in the laboratory on three water regimens that represented a gradient of water stress, but food was available ad libitum. When subjected to increasing degrees of water stress, urine osmotic concentrations increased, feces became drier, and body—water turnover rates, determined with tritiated water, decreased. When subjected to the severest water stress, diurnal torpor occurred and apparently caused a decline in urine concentration and an increase in fecal water content during the daytime. Urine osmotic concentrations and fecal water contents of midsummer mice in the field were similar to values for mice subjected to severe water stress in the laboratory. In late summer, however, the values indicated low water stress. The lower water exchange during midsummer, as determined by tritiated—water turnover, indicated that the greater water stress at this time was at least partly due to a reduced availability of water compared to late summer. During both periods food was the only apparent source of water. Mice in midsummer were feeding primarily on insects, foliage, and fungi, but during late summer, when acorns became available, they switched to this as the predominant dietary component. Acorn utilization was accompanied by onset of female reproductive activity and body weight increases for both sexes. It is suggested that water stress was alleviated by the acorn diet and was responsible for the lack of reproductive activity and depressed body weights for several months during summer.

Water metabolism in grazing cattle

Abstract Body water cantent and water turnover were measured in lactating and dry cows grazing clover-dominant pastures. Among 12 pairs of identical twins there was a closer within-twin relationship of body weight and body water content than water turnover. Water turnover was significantly correlated with body water content and milk production. Herd average for the half-life of water was 2.0–2.4 days for lactating cows and 2.8–3.3 days for dry cows. No relationship was found between water turnover and the susceptibility of cows to bloat. During severe bloat, cows dosed with anti-bloat had higher water turnovers and lower bloat scores than their untreated twins.

Tritiated Water-Turnover Rate in Rodents: Desert and Mountain

pret. The discovery of the usefulness of tritiated water (TOH) in measurement of total body water (Pace et al. 1947) has offered a practical method for the study of daily water exchange. This technique has been verified in man (Pinson and Langham 1957) and in several other mammalian species (Reid, Balch, and Glascock 1958; Richmond, Langham, and Trujillo 1962; Holleman and Dieterich 1973; Yousef 1973). Using TOH, one can measure the rate of body water utilized per day including water imbibed, food water, and metabolic water.

The biology of kangaroos (Marsupialia‐Macropodidae)

ABSTRACTKangaroo is taken as a general term embracing all members of the marsupial family Macropodidae, although special reference is made to the larger species Megaleia rufa, Macropus robustus, M. giganteus and M. fuliginosus.The origin and evolution of the Metatheria is traced from their divergence from the Eutheria during the early Cretaceous. The entry of Metatheria into Australia probably took place during the Eocene via Antarctica. During the Pliocene there was a marked radiation, within this stock, of forms adapted for grazing. The biology of modem species is considered in relation to their distribution in and adaptation for hot, arid areas with seasonally poor quality food.Kangaroos are efficient homeotherms and their main avenue of heat loss at high temperatures is by panting, with sweating and saliva‐spreading in extreme conditions. Their low level of oxygen metabolism is of advantage in hot arid conditions. post‐partum fertilization is maintained in the uterus during pouch‐suckling of another young, may be an adaptation to allow replacement of young lost by accident or drought, but it may also be 3 general reproductive adaptation of marsupials.The water relations of kangaroos demonstrate a high degree of adaptation to an arid environment. The marsupial characteristic of low body water turnover is combined with high total body water and the capacity to survive weight loss during dehydration typical of ruminant and ruminant‐like animals. In addition, desert kangaroos exhibit the ability of many other desert‐adapted mammals to reduce water loss by evaporation and from urine and faeces during dehydration, and to recycle urea when nitrogen and water are in short supply.The large kangaroos are well adapted to the utilization of poor quality food, with ruminant‐type digestion and nitrogen and water conservation by urea recycling. The diet of large kangaroos includes a large proportion of grass, and does not generally overlap greatly with that of sheep. In kangaroos of arid and semi‐arid areas, food, water and shelter are important factors controlling distribution, with food the most important.Reproduction in kangaroos is greatly affected by the severe environmental conditions imposed by drought. The onset of sexual maturity in females is delayed, there is increased mortality of pouch‐young due to failure of lactation, and if drought continues, females enter anoestrus and breeding ceases. Embryonic diapause, whereby a dormant embryo from aThe family Macropodidae includes some of the most social marsupials. The large, partly diurnal grazing animals of open habitat generally exhibit some form of group cohesion, with a low level of social organization.In the natural regulation of numbers, predators and disease appear relatively unimportant. Rainfall via its effect on food supply is a most important factor controlling numbers. Other such factors are habitat destruction, which is most significant for small species, and commercial exploitation by shooting, which is most significant for large species. However, regulations arein force to control shooting of the large species and there is little likelihood of their extinction from this cause alone.

Water metabolism in perameloid marsupials from different environments

1. 1. Total body water and water turnover was measured using tritiated water in one desert and two temperate zone perameloid marsupials. 2. 2. Under ad lib. conditions all perameloid marsupials had, in line with their low metabolic rates, low water turnovers and during water restriction water turnover was reduced to very low levels. 3. 3. Water intake and loss was partitioned during both ad lib. and restricted water intake. 4. 4. All species had maximal urine concentrations in the range 3000–4000 mOsmole/kg. 5. 5. In Isoodon macrourns lactation was shown to result in a slightly greater total body water and a 36 per cent increase in water turnover.

Observations on the Breeding Adaptations of the Roadrunner

The Roadrunner (Geococcyx californianus) is a diurnal ground-dwelling cuckoo, which is a permanent resident in the arid and semiarid regions of southwestern North America. Some features of its physiology are known (Calder and Bentley 1967; Calder and Schmidt-Nielsen 1967; Calder and Schmidt-Nielsen 1968; Calder 1968). However, the presence of a salt-secreting nasal gland (Ohmart 1972) and studies on the efficiency in body water turnover in birds under simulated desert conditions (Ohmart et al. 1970) indicated that detailed field information was needed to inte-

Body Water Content and Turnover in Several Species of Rodents as Evaluated by the Tritiated Water Method

Body water content and turnover were determined on 80 rodents, representing 12 species, using the tritiated water method. All experimental rodents were maintained under similar laboratory conditions. Measurements of body water content indicated wide variability in the degree of body fatness. Mean values of body fat as a percentage of body weight ranged from 3.0 to 38.8 per cent for the 12 species. The equation, WTR = n (LBM)b, was used to relate water transfer rate (WTR) to lean body mass (LBM). The overall exponent (b) for 12 species of rodents equaled 0.78 ? 0.044 (standard deviation) and represents the interspecies esti- mate. The exponent computed for three species of the genus Microtus equaled 0.69 ? 0.093. Specific water transfer rates ranged from 0.34 to 1.76 (ml/g'69)/d. In general, water transfer rates were correlated with water availability in the natural habitat of each species. Species inhabiting moist areas had high specific water transfer rates while species inhabiting arid regions had lower specific water transfer rates. Water content of fat-free body tissue is essentially constant among homeo- therms (Reid, 1967). However, the kinetics of body water are variable (Rich- mond et al., 1962). Within the order Rodentia rates of body water turnover are diversified. Rapid rates of water turnover may be found in semiaquatic species such as the muskrat, whereas slower rates of water turnover would be expected for the desert adapted kangaroo rat. Factors influencing body water turnover in rodents include metabolic rate, body size, environment, and species. The introduction of tracers of water has provided a sophisticated tool for determining water content and turnover in biological systems without drasti- cally disturbing the system. Several tracers have been used and compared (Reid et al., 1958). However, tritiated water possesses several advantages over other tracers. It was used in this study. The primary objective of this study was to determine the body water con- tent and turnover in several species of rodents maintained under similar labo- ratory conditions. An ancillary objective was to consider factors contributing to variability in body water turnover in rodents.

Dynamics of water-isotope distribution.

Dynamics of water-isotope distribution.

Influences of Sex and Egg Production on Water Turnover in Chickens

Total body water pool volumes and rates of body water turnover were measured in cocks and in nonlaying and laying hens. The body water half life (t½) and total body water in percent of body weight was significantly less in nonlaying hens than in cocks. During egg production the body water pool size of hens increased significantly and the t½ decreased significantly. The increased flux of water of hens during egg production was far more than could be accounted for as water lost in the eggs alone. The body water pool size or its rate of turnover in cocks did not change significantly.

The effect of withholding drinking water on wool growth and lamb production of grazing Merino sheep in a temperate climate

Drinking water was withheld from grazing pregnant and non-pregnant Merino ewes for a period of 12 months in an experiment carried out near Armidale, N.S.W., lat. 30° S., altitude 1000 m. There was no reduction in the wool production or liveweight of, or the number of lambs born to, ewes without drinking water as compared with ewes with water supplied. There was a significant reduction in the birth weight of the lambs of ewes without drinking water. Body water turnover rates were similar in sheep with and without water in the cooler months but a combination of climatic effects resulted in considerably lower water turnover rates of the sheep without water in early summer. Lactation, together with a low pasture water content and moderately high thermal loads in late December, resulted in a 25% mortality of the mated ewes without drinking water and the subsequent death of their lambs. Removal of the remaining ewes and lambs to green pasture immediately stopped the deaths although no drinking water was supplied. There were no deaths in the unmated ewes. The survival of most of the ewes when deprived of drinking water reflects in part the temperate climate of the Armidale area, where mean daily air temperatures during summer do not exceed 25°C and rain usually falls in each month of the year.

Seasonal changes in total body water, extracellular fluid, and blood volume in grazing reindeer.

The effects of climatic and nutritional changes on body fluid compartmentalization and turnover were investigated in grazing female reindeer. Total body water volume and turnover, extracellular fluid volume, and blood volume were estimated using tritiated water, sodium sulfate-35S, and sodium chromate-51Cr, respectively. During winter and spring, body weights were either maintained or reduced while total body water (percentage of body weight) increased, resulting in appreciable losses of total body solids. In summer, large gains in body weight were accompanied by reduced total body water volumes resulting in substantial increases in body solids. An apparent fluid shift from the intravascular to the extracellular compartment during late spring suggested the occurrence of a starvation edema. Mean water flux rates (ml/day per kilogram body weight) were higher in late spring than during other seasons; lowest values were recorded in early winter. Seasonal variations in nutritional status as reflected by body composition and fluid compartmentalization, and changes in water turnover are discussed in relation to climate and the quality and availability of forage. The complicating influences of pregnancy and lactation are also considered.

Water turnover in coturnix quail with individual observations on a burrowing owl, petz conure and vulturine fish eagle

1. 1. The body-water half-life in coturnix quail was 2·1 days and the turnover was 0·2 ml water/g body wt. per day. There was no evidence of sexual dimorphism. Male coturnix drank about 24 ml water/day, and it was calculated that about 95 per cent of the water turnover can be provided by free drinking water. 2. 2. The half-life of body water was about 4 days in the burrowing owl, 7–8 days in the Petz conure and 6 days in the vulturine fish eagle. 3. 3. The turnover of body water appeared to be related to body size.

Energy metabolism and body water turnover rates of two species of free-living kangaroo rats, Dipodomys merriami and Dipodomys microps

1. 1. The energy metabolism and comparative body water turnover rates of two species of kangaroo rats, Dipodomys merriami and Dipodomys microps, were measured in the natural environment over a 1-yr period with the D 2 18O method. 2. 2. In addition to yielding energy metabolism data indicative of active, non-postabsorbtive animals, the results suggest that both species undergo diurnal torpor during periods of cold stress. 3. 3. Comparative water metabolism data indicate that D. merriami possesses a more conservative body water turnover rate than does D. microps. 4. 4. The D 2 18O method of studying animal energy metabolism in the natural environment yields data not obtainable through conventional laboratory methods. It is preferable, therefore, that where practicable this method be employed in investigations of animal physiological ecology unless there is reasonable assurance that laboratory methods are adequate.

The Pathophysiology of Ovine Ostertagiasis: Water Balance and Turnover Studies

SUMMARY Body water turnover and water balance were investigated in 6 sheep experimentally infected with Ostertagia circumcincta, and in 6 pair-fed controls. A substantial reduction in food and water intake occurred, causing a marked prolongation in body water half-lives. There was no evidence of alteration in the distribution of water output between the various excretory routes. The results of the study indicate that the reduction in body water turnover observed in the injected animals is principally due to the anorexia induced by the parasitic injection.

The estimation of milk intake and growth of beef calves in the field by using tritiated water

The growth of Hereford, Friesian x Hereford, and Friesian x Shorthorn calves was studied under grazing conditions in the south-east of South Australia during the autumn period of minimal dry pasture. Measurements of body water content, water turnover, and body weight changes of calves were undertaken during an 8-week period after calving in February 1968. From these measurements, estimates were made of liveweight gain and the yield of body solids per unit of water turnover (milk intake). The subsequent development of the calves was also measured. The average birth weights of the three groups were not significantly different. The 8-week total of water intake (milk) was 405 � 14.3 1. in Shorthorn cross calves, 279 � 18.0 1. for Hereford cross, and 263 � 14.3 1. among the Herefords. Over the first 8 weeks body weight gain (g/24 hr) was highest in the Shorthorn cross calves and their body solids gain was 63 % greater than that of the Hereford cross calves but only 29 % greater than that of the Hereford calves. Water turnover (1.124 hr) of the Shorthorn cross calves was 45 % greater than that of the Hereford cross calves and 54% greater than that of the Hereford calves over the 8-week period. There was no significant difference between the three groups in body weight or solids gain per unit of milk intake (g/l), though the average conversion of milk to solids by Herefords was greater than that of the other breeds. The Shorthorn cows weighed less than the other groups after calving and their average relative and absolute loss of weight during lactation was greatest. The offspring of the Shorthorn cows had the highest water intake expressed as a function of the body weight0.75 of the cows. The water turnover of Shorthorn calves as a function of calf weight0.82 was also greater than that of the other calves. The correlations between body weight gain (g/24 hr) and water turnover (l./24 hr) and between body solids gain (g/24 hr) and water turnover (l./24 hr) were 0.815 (P < 0.001) and 0.632 (P < 0.01) respectively. The correlation between cow body weight loss and calf body weight gain was 0.481 (P < 0.05). A group of nine Friesian x Hereford calves studied for 11 weeks after calving in April 1969 on newly grown winter rainfall pasture 50 km north of Adelaide had both average water turnover (l./24 hr) and body weight gains (g/24 hr) substantially higher than those of any group in the previous year. The efficiency of conversion estimated as body solids gain and body weight gain per unit of water intake was, however, similar to those of the Hereford calves in 1968. The differences between the years are presumed to follow from differences in the amount of pasture available in the dry season, relative to pasture after the rains had come. Average body water content (TOH space) was 801 ml/kg body weight at the beginning of the measurements and gradually fell to 713 ml/kg at 11 weeks.

Growth and water metabolism of cows and progeny on fertilized and unfertilized tropical pastures

Growth of Brahman x Shorthorn cows and their calves grazing unfertilized and fertilized pasture was studied in relation to body water content and water turnover; the main plant species in the pasture were spear grass (Heteropogon contortus) and Townsville stylo (Stylosanthes humilis). During the dry season, prior to the birth of calves, there was little difference in body weight or body composition between cows from the unfertilized and fertilized areas, despite the greater yield of pasture on the latter. The increase in body weight of both groups after the onset of the new season was due to expansion of the body water space. Body solids did not increase until c. 2 months later. The cattle from the fertilized pasture continued to increase in weight over the entire wet season at a significantly faster rate (P < 0.001) than those in the unfertilized pasture, and this latter group ceased growing a month before the end of the season. There was no significant difference in birth weight between the two groups of calves, although those from the fertilized pasture were significantly heavier at 2 weeks of age; during these 2 weeks they had received 45 % more milk, and until about 20 weeks they continued to grow more rapidly and turn over more water than the group from the unfertilized pasture. From 20 weeks the quality of the forage in the unfertilized pasture became superior, owing to the relatively high proportion of legume (Stylosanthes humilis), and the calves from the unfertilized pasture grew more rapidly until the end of the wet season. Plant nitrogen content was reflected in plasma urea nitrogen levels. The relationship between pasture quality and growth of cows and their calves is discussed.