Showing papers on "Body water published in 1983"
TL;DR: The difference in RMR between the sexes is probably caused by the higher proportion of fat-free mass in men, whether determined from body water, body potassium, or a formula using both water and potassium.
168 citations
TL;DR: A new method for the estimation of body composition in human subjects is described which entails the measurement of total body electrical conductivity, based on the principle that the electrical Conductivity of lean tissue is far greater than that of fat.
114 citations
TL;DR: The reduction of LBM appeared to be complete after the first month of flight and thereafter was largely independent of mission duration, diet, and exercise.
91 citations
TL;DR: The predominant mechanism in fluid intake during exercise and heat exposure is concluded to be the renin-angiotensin II system in the presence of reductions in total body water and extracellular plasma volumes.
Abstract: The interactions between fluid intake and balance, and plasma ion, osmotic, and endocrine responses during dehydration produced by exercise in cool and warm environments during acclimation are explored. Two groups of five male subjects performed 8 days of ergometer exercise in hot and thermoneutral conditions, respectively. The exercise trials lasted 2 hr each. Monitoring was carried out on the PV, osmotic, sodium, and endocrine concentrations, voluntary fluid intake, fluid balances, and fluid deficits. A negative correlation was observed between the plasma sodium and osmolality during acclimation. The presence of hypervolemia during acclimation is suggested as a cause of drinking, while the vasopressin concentration was not found to be a significant factor stimulating drinking. Finally, the predominant mechanism in fluid intake during exercise and heat exposure is concluded to be the renin-angiotensin II system in the presence of reductions in total body water and extracellular plasma volumes.
84 citations
TL;DR: It is suggested that under heat-induced dehydration, both the extra- and intracellular fluid compartments of muscle and skin play an important role in the compensation of water loss and in the maintenance of circulation to the brain and liver.
Abstract: Dehydration amounting to about 10% of body weight was induced in adult male rats by exposure to a hot, dry environment (D.B.T., 36°C; R.H., 20%) over 6 to 8hr. The volumes of total water (TW), extracellular fluid (ECF), and plasma (PV) were determined both on individual tissues and on the whole body using the constant dry weight as well as 51Cr-EDTA and 125I-RIHSA dilution methods. Total body water (TBW), intracellular (ICF), and interstitial (ISF) fluid volumes were calculated from these data.The 10% loss of body weight caused a decrease in TBW by 17% from the control value; 41% of this loss was from ICF, 47% from ISF, and 12% from PV. The decrease of ISF was proportional to that of PV and the water loss from ICF was caused by an increase in plasma osmolality. As to the water loss from organs, 40% of the whole body water loss came from muscle, 30% from skin, 14% from bone, and 14% from viscera. The G.I. tract had the highest tendency to lose water while the brain and liver showed the least.These findings suggest that under heat-induced dehydration, both the extra- and intracellular fluid compartments of muscle and skin play an important role in the compensation of water loss and in the maintenance of circulation to the brain and liver.
70 citations
TL;DR: A study in which total body electrical conductivity measurements and lean body mass estimated from hydrostatic weighing in human subjects were compared and the TOBEC measurement was found to be extremely reliable and to correlate highly with hydrostatically estimated LBM.
Abstract: This article reports a study in which total body electrical conductivity (TOBEC) measurements and lean body mass (LBM) estimated from hydrostatic weighing in human subjects were compared. The TOBEC method provides a new approach to assessment of human body composition that is based on the principle that the electrical conductivity of lean tissue is far greater than that of fat. In a sample of 32 men and women varying widely in age (20 to 53 years), body weight (45 to 155 kg), and adiposity (9.5 to 53.0% body fat), the TOBEC measurement was found to be extremely reliable (r = 0.999) and to correlate highly with hydrostatically estimated LBM (r = 0.903, P less than 0.0001). When the TOBEC scores were transformed to provide a single variable; namely, the subject's height times the square root of the TOBEC score, a higher correlation with LBM was obtained (r = 0.943). Taking gender into account further enhanced the prediction of LBM from TOBEC (r = 0.951). These observations strongly reinforce the results of a previous investigation in which high correlations were found between TOBEC and both total body potassium and total body water. Accordingly, this new method promises to provide a useful technique for the evaluation of body composition that is at once simple, rapid, objective, and noninvasive.
69 citations
TL;DR: An analysis of model predictions indicates that a reasonable estimation of total body water and the intracellular to extracellular volume ratio enables us to accurately predict the magnitude of transcellular fluid shifts induced by hemodialysis as well as the postdialysis serum sodium concentration and osmolality.
67 citations
TL;DR: It was concluded that it is particularly important to measure protein stores of MHD patients with low protein intake to ascertain nutritional status, and in vivo measurement of total body nitrogen and potassium for determination of body composition provides a simple, direct, and accurate assessment of the nutritional status of M HD patients.
61 citations
Journal Article•
TL;DR: With the age and sex‐specific FFBM: total body water ratios and densities of FFBM presented it will be possible to avoid systematic underestimation of fat content from measurements oftotal body water and overestimation offat content from determinations of body density by underwater weighing.
Abstract: This study was undertaken to obtain total body water (TBW) data suitable for derivation of body composition of the typical adolescent male. TBW by the deuterium dilution method, stage of sexual development and anthropometric parameters (weight, height and triceps and subscapular skinfold thickness) were determined in 108 males between 10 and 14 years of age, whose weight and height fell between the 10th and the 90th percentile of the NCHS reference data. TBW/weight did not change significantly between 10 and 14 years, although a slight increase after age 11 years and from genital stage 2 to stage 5 was present. This indicates that body fat content decreases after 11 years and after genital stage 2, especially if the fact is taken into account that water content of fat-free body mass decreases during this age period. The ability of single anthropometric parameters to predict TBW/weight was low (subscapular skinfold thickness, r = -0.62; triceps skinfold thickness, r = -0.54; weight/height cube ratio, r = -0.48). Even with the use of various combinations of anthropometric parameters in multiple stepwise prediction equations it was not possible to explain more than 50% of the variation of TBW/weight and the high standard error of the estimate indicated large errors in prediction. Thus, body composition of normal adolescent males cannot be predicted with an acceptable degree of accuracy by anthropometric parameters. On the other hand, the deuterium dilution method using salivary water represents a noninvasive method for the determination of TBW which is quite simple and suitable for field studies.
55 citations
TL;DR: In obese hypertensive subjects, the IBW/IFV ratio was significantly increased in comparison with both control subjects and nonobese hypertensive patients, causing an altered partition between the intracellular and the interstitial spaces.
Abstract: Intraarterial blood pressure, plasma volume, extracellular and interstitial (IFV) fluid volumes, and total and intracellular (IBW) body water were evaluated in 50 men: 16 obese hypertensive patients, 16 nonobese hypertensive patients, and 18 normal subjects of similar age. In obese hypertensive subjects, the IBW/IFV ratio was significantly increased (p
47 citations
01 Jan 1983
TL;DR: The disappearance rate of intravenously injected Evan's Blue dye from the circulation (EBDR) has been studied in 21 normotensive primigravidae and 23 primig Gravidae with proteinuric pre-eclampsia and results in differences in plasma volume in pre- eclamptics depending on the method of calculation.
Abstract: The disappearance rate of intravenously injected Evan's Blue dye from the circulation (EBDR) has been studied in 21 normotensive primigravidae and 23 primigravidae with proteinuric pre-eclampsia. The EBDR is faster in those with pre-eclampsia and results in differences in plasma volume in pre-eclamptics depending on the method of calculation. The EBDR correlates with serum albumin concentration and total body water in pre-eclamptics, but not in normotensive pregnancies.
TL;DR: Results indicate that propranolol had little effect on glomerular filtration rate (less than 10% decrease); changes that did occur were directly correlated with changes in effective renal plasma flow.
Abstract: Fourteen hypertensive men underwent assessment of renal function and body fluid composition following short-term (three to six weeks), long-term (five to six months), and withdrawal (two weeks) of propranolol hydrochloride monotherapy for the treatment of hypertension. Results indicate that propranolol had little effect on glomerular filtration rate (less than 10% decrease); changes that did occur were directly correlated with changes in effective renal plasma flow. Propranolol therapy decreased effective renal plasma flow 14% and renal blood flow 15% during long-term therapy; decreases in renal perfusion persisted following withdrawal of therapy. Propranolol therapy was neither antidiuretic nor antinatriuretic; propranolol had no effect on urine osmolality, free water clearance, sodium clearance, or fractional sodium excretion. Furthermore, propranolol therapy did not expand plasma volume, extracellular fluid volume, or total body water. Finally, propranolol therapy had no effect on the renal handling of potassium or on serum potassium concentration.
TL;DR: Total body D2O space provided as accurate an estimate of empty body water as the early-pool technique and may be easier to use because catheterization of blood vessels is not required, while the incorporation of live weight and sex in multiple regression equations did not improve the accuracy ofempty body water prediction over that obtained from D1O measurements alone.
Abstract: An experiment involving 73 pigs was conducted to evaluate the efficacy of the deuterium oxide (D/sub 2/O) dilution procedure for in vivo estimation of body composition in swine. Pigs were infused with known quantities of D/sub 2/O at 6.4 and 18 kg and then at approximately 18 kg increments to 145 kg body weight. Postinfusion blood D/sub 2/O concentrations were partitioned into early- and total-equilibrating pools. Results from D/sub 2/O analyses were compared with empty (ingesta-free) and total body water values obtained from chemical analysis of the ground animals. Both early- and total-equilibrating D/sub 2/O pools seemed to be good estimators of empty body weight. Total body D/sub 2/O space was similar to total body water at 6.4 kg, but consistently overestimated body water (averaged 20%) as the pigs attained heavier weights. Early- or total-body D/sub 2/O pool measurements accurately predicted chemically determined components with residual coefficients of variation below 5% and R2 greater than or equal to .90. However, total body D/sub 2/O space provided as accurate an estimate of empty body water as the early-pool technique and may be easier to use because catheterization of blood vessels is not required. The incorporation of live weight and sex inmore » multiple regression equations did not improve the accuracy of empty body water prediction over that obtained from D/sub 2/O measurements alone. A method to estimate total body composition (water, protein, fat, ash) from the total body D/sub 2/O space measurements is presented.« less
TL;DR: The findings suggest that hypoxia in this condition suppresses the hypothalamus or pituitary or both and that such suppression is reversible and cast doubt on isotope dilution methods for measuring body water compartments in disease states likely to cause changes in cell permeability.
Abstract: Serum testosterone, follicle-stimulating hormone, luteinising hormone, and dihydro-epiandrosterone concentrations rose significantly in seven men studied during recovery from a severe exacerbation of chronic obstructive airways disease. Urinary 17-ketosteroids also rose significantly though serum androstenedione and prolactin concentrations did not. Our findings suggest that hypoxia in this condition suppresses the hypothalamus or pituitary or both and that such suppression is reversible. In view of previous reports of increase in total body potassium and intracellular water with recovery from cor pulmonale, we also carried out metabolic studies on our patients. Low body potassium concentrations in cor pulmonale fell further with recovery, in part reflecting a fall in lean body tissue. Intracellular water appeared to increase on recovery despite a fall in other lean body mass indices (the simplest and most reliable being skinfold thickness). We suspect this result to be spurious and due to problems with equilibration in isotope dilution. Alternatively it may reflect waterlogging of cells. A false figure for intracellular water could be responsible for an unexpectedly low estimated intracellular potassium concentration on recovery. Our results cast doubt on isotope dilution methods for measuring body water compartments in disease states likely to cause changes in cell permeability.
TL;DR: The technique of prompt gamma neutron activation analysis can be used effectively to determine long term changes in total body nitrogen during weight reduction, and loss of lean tissue (water, potassium and nitrogen) as well as fat tissue occurred during weight Reduction.
Abstract: The purpose of this study was to compare the effects of two isocaloric diets (800 Kcals) on the changes in body composition during weight reduction. While the protein content of both diets was 70 g, the carbohydrate content of diet A was 10 g and that of diet B was 70 g. The various parameters of body composition were determined as follows: Total body potassium (TBK) by 40 K counting, total body water (TBW) by the tritated water technique, total body nitrogen (TBN) by prompt gamma neutron activation analysis (PGNAA) and total body fat was estimated by measuring the skinfold thickness. Routine serum chemistries were performed every 2 wk and serum insulin and triiodothyronine by radioimmunoassay were done at 4-wk intervals. Seventeen obese women who were at least 30% above ideal body weight volunteered for the outpatient study. (group A—10 subjects, group B—7 subjects). At the end of the 12 wk study, the percent changes in the above parameters of body composition were not significantly different for the two groups. The biochemical changes were consistent with the degree of caloric restriction. We conclude that: (1) the technique of prompt gamma neutron activation analysis can be used effectively to determine long term changes in total body nitrogen during weight reduction, (2) loss of lean tissue (water, potassium and nitrogen) as well as fat tissue occurred during weight reduction. The loss of TBN in absolute quantities was less for diet A compared to diet B; however, there was no significant difference between the two diets when the data was expressed as a percent change from the baseline values, and (3) TBK determination probably provides the best estimate of total body fat.
TL;DR: In this paper, five male rats were exposed to 18.5 days of weightlessness in the Soviet mission COSMOS 1129 (flight group) and killed after reentry, and they were immediately dissected into three major body subdivisions: musculoskeletal system, skin, and pooled viscera analyzed for fat, water, solids, and six elements.
Abstract: Five male rats were exposed to 18.5 days of weightlessness in the Soviet mission COSMOS 1129 (flight group) and killed after reentry. They were immediately dissected into three major body subdivisions: musculoskeletal system, skin, and pooled viscera analyzed for fat, water, solids, and six elements. These results, expressed as percentages of the fat-free body or its components, were compared with two groups of terrestrial controls: one subjected to a flight simulation in a spacecraft mock-up and the other under standard vivarium conditions. Relative to the control groups the flight group showed 1) a reduced fraction of total body water, 2) a net shift of body water from skin to viscera, 3) a marked diminution in fraction of extracellular water in the fat-free body, 4) a marked reduction in fraction of bone mineral, 5) no change in the quantity of stored fat or adrenal masses, and 6) a net increase in total muscle mass as indicated by total body creatine, protein, and body cell mass.
TL;DR: Results indicate significant ISF volume expansion occurs in SHR prior to elevation of blood pressure, and the previously observed elevation in plasma aldosterone inSHR at this age probably mediates the volume expansion.
Abstract: To ascertain the effect of aldosterone on body fluid volumes in neonatal, prehypertensive spontaneously hypertensive rats (SHR), we studied these animals at 12 days using age-matched Wistar-Kyoto (WKY) as normotensive controls. Some pups of each strain were treated with spironolactone (1.5 micrograms/g body wt) on days 10-12. Total body water (TBW, by dessication) and extracellular fluid (ECF, Na2 35SO4 space) volumes were significantly larger in SHR than in WKY, whereas plasma volumes (125I-serum albumin space) were not different. Thus the enlarged ECF was due to preferential expansion of the interstitial fluid (ISF) space. Treatment of SHR with spironolactone reduced TBW and ISF to values not different from untreated WKY and also reduced plasma volume to some extent. These results indicate 1) significant ISF volume expansion occurs in SHR prior to elevation of blood pressure, and 2) the previously observed elevation in plasma aldosterone in SHR at this age probably mediates the volume expansion.
TL;DR: It is suggested that moderate polycythemia in normal term neonates does not affect total and extravascular body water estimates, but that a fluid shift from the extracellular to the intracellular space may accompany the exchange procedure.
TL;DR: An isotonic fluid load was given to rats by infusing 12 ml saline i.v. in 60 min, and the total extracellular fluid volume increased, while the total plasma water measured with RIHSA remained unchanged.
Abstract: An isotonic fluid load was given to rats by infusing 12 ml saline iv in 60 min The plasma water and extracellular fluid volumes of the whole animal and selected tissues were subsequently studied with 125I human serum albumin and 51Cr EDTA The fluid infused was equivalent to 130% of the plasma water volume The total extracellular fluid volume increased by 17%, while the total plasma water measured with RIHSA remained unchanged The regional extracellular fluid volumes increased in the lung (14%), the gastric fundus (15%), large intestine (21%) and skin (28%) The results illustrate the selective distribution of an isotonic fluid overload, those tissues being effected having high compliances
TL;DR: This study correlates changes in skeletal muscle composition with whole body electrolyte and nitrogen balance in an attempt to establish the contribution made by skeletal muscle to the changes in whole body fluid and electrolyte composition.
Abstract: Nutritional depletion and repletion are associated with changes in the size of the extracellular and intracellular fluid compartments. Although the effect of nutrition on whole body composition is well established, the distribution of changes among the various body tissues is not. This study correlates changes in skeletal muscle composition with whole body electrolyte and nitrogen balance in an attempt to establish the contribution made by skeletal muscle to the changes in whole body fluid and electrolyte composition. Total parenteral nutrition was administered to ten patients for 16 to 25 days. Oxygen consumption, CO2 production, and balances of N, Na, and K were measured daily. Muscle biopsies were taken prior to administration of TPN, in the middle, and at the end of the nutritional regimen. Prior to administration of parenteral nutrition, muscle concentrations of water, sodium, and chloride were significantly higher than normal. With institution of the nutritional support regimen, all three concentrations decreased. The calculated loss in muscle water could account, at most, for only one-sixth of the loss in total body water. Muscle Na loss could account for approximately one-half of the whole body change. Potassium concentrations in the depleted patients were not significantly decreased from normal values and showed a negligible increase with TPN. Since the ratio of K to dry fat-free solids in muscle was constant, most of the whole body changes could be accounted for by assuming that nearly all N is deposited in muscle. Nutritional support results in restoration of cell mass with a contraction of the extracellular fluid (ECF) compartment. The changes in the ECF must occur in tissues other than muscle, while the restoration of cell mass occurs primarily in muscle.
TL;DR: It is demonstrated that AV3V periventricular ablation results in chronic alterations in the normal body fluid distribution but does not diminish the rats' ability to increase Prenin and Paldo or decrease sodium excretion during volume depletion.
Abstract: The effects of electrolytic ablation of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) of the rat brain on body fluid distribution and the renin-aldosterone system were determined. Rats underwent either ablation of AV3V periventricular tissue or control surgeries. After recovery, animals were implanted with femoral arterial and jugular venous catheters, and sodium space and plasma volume were measured by calculating the dilution of intravenous injections of 22Na- and 125I-labeled serum albumin, respectively. Total body water was determined in separate groups of rats by desiccation. Other animals with AV3V lesions and control rats were used to measure urinary sodium excretion and plasma renin (Prenin) and aldosterone (Paldo) concentrations while volume replete and after volume depletion. Animals with AV3V lesions had expanded extracellular fluid volume and decreased plasma volume, but total body water was comparable with control-operated rats. Volume-replete and volume-depleted rats with AV3V lesions had significantly higher Prenin than control animals in similar volume states. Although Paldo was not different between groups in the volume-replete state, it was significantly greater in rats with AV3V lesions than in control animals after volume depletion. These data demonstrate that AV3V periventricular ablation results in chronic alterations in the normal body fluid distribution but does not diminish the rats' ability to increase Prenin and Paldo or decrease sodium excretion during volume depletion.
TL;DR: Data indicate normal body retention of 51Cr despite body water pool turnovers of up to 100% per day, presumably due to Cr reabsorption at a proximal site within the nephron, and renal handling of Cr is flow-independent.
Abstract: The effect of free water diuresis by three different modalities on body 51Cr conservation and distribution was studied in adult male rats. Despite massive diuresis, ADH deficiency had little effect on body 51Cr retention or relative tissue distribution of 51Cr but did induce 25-40% increases in serum 51C concentrations which were reversible by pitressin administration. Glucose feeding produced copious diuresis but no change in body 51Cr retention or relative tissue distribution of 51Cr. The serum 51Cr concentration decreased 23% in association with small increases in serum glucose and insulin concentrations. LiCl administration produced moderate diuresis with little change in body 51Cr retention and inconsistent changes in serum and tissue 51Cr distribution. These data indicate normal body retention of 51Cr despite body water pool turnovers of up to 100% per day. Hence, renal handling of Cr is flow-independent, presumably due to Cr reabsorption at a proximal site within the nephron. However, a marked rest...
TL;DR: Although there are minor differences in body water contents and distribution between baboon and human neonates, baboon data are sufficiently similar to human data to justify using the baboon fetus and neonate as a model for investigations of human development.
Abstract: Water contents of various body water compartments were estimated within nine hours of birth in 11 preterm and eight term baboon (Papio cynocephalus neonates. Estimated water contents of all body compartments (in ml) increased linearly with birthweight (r = 0.52 to 0.90, P ≦ 0.007) and with gestational age (r = 0.46-0.94, P ≤ 0.05). When body water estimates were expressed in proportion to bodyweight (in ml/kg), preterm neonates had significantly larger mean antipyrine space and intracellular water than their term peers. Mean corrected bromide space, interstitial water, plasma volume, blood volume, and red cell volume were similar in preterm and term neonates. Although there are minor differences in body water contents and distribution between baboon and human neonates, baboon data are sufficiently similar to human data to justify using the baboon fetus and neonate as a model for investigations of human development.
TL;DR: Intracellular potassium was studied in patients with predialysis chronic renal failure by the use of skeletal muscle biopsies and whole-body counting and therapy was unaviation for various clinical reasons.
Abstract: Intracellular potassium was studied in 11 patients with predialysis chronic renal failure by the use of skeletal muscle biopsies and whole-body counting. For various clinical reasons, therapy was unav
TL;DR: Results indicate that in addition to water loss, depletion of body tissue, including protein, occurs in the newly-weaned sow.
Abstract: The loss of body water of eight sows in the 7 d following weaning was determined using the deuterium oxide dilution technique. Four of the sows had received a concentrate diet in restricted amounts while the other four had been given the same diet mixed with two-thirds its weight of oat husks ad lib. during the whole of the preceding lactation. Certain blood and urine constituents were also measured. Loss of body water was significantly less (P less than 0.05) than weight loss of fasted animals, but body water losses were considerable in six of the eight animals. Excretion of urinary nitrogen, urea and creatinine and levels of plasma urea were higher, while levels of plasma non-esterified fatty acids and the hydroxyproline index were lower 1 week after weaning compared with values obtained on the day following weaning. These results indicate that in addition to water loss, depletion of body tissue, including protein, occurs in the newly-weaned sow.
TL;DR: It is suggested that changes in total body water occur as a result of excessive fat accretion during fetal life as well as the effect of neonatal macrosomia or maternal diabetes on extracellular and intracellular water estimates.
TL;DR: In this article, the water metabolism of 103 newborn babies was determined over the first 10 postnatal days, by measuring water turnover rates by means of an isotope dilution technique, which involves the oral administration of the nonradioactive isotope of water, 2H2O and the measurement of its urinary excretion by infrared spectrophotometry.
TL;DR: Pregnant and nonpregnant rat carcasses were analyzed gravimetrically for water and for hexane extractable fat and the WLT was calculated and body fat estimates derived from the mean WLT may be very inaccurate, particularly in fasted individuals.
01 Jan 1983
TL;DR: In this paper, the skeleton is the major body store of phosphorus, but does not appear to have been studied quantitatively with a view tonderiving an objective definition of body phosphorus status.
Abstract: The major nutritional limitations to cattle production in tropicalnand subtropical areas of Australia are deficiencies of energy, proteinnand phosphorus, which are often very severe. A dietary deficiency of anynone of these nutrients results in suboptimal feed intake, and hencenreduced rates of growth and reproduction.The study of energy, protein and phosphorus nutrition involvesnconsideration of both nutrient supply and requirements. In the case ofnsupply, the nutrients may come from either the feed or from body tissuenstores of energy (fat and protein), protein and phosphorus. Thenmagnitude of these stores governs the extent of an animal's ability tonwithstand dietary deficiency, and thus assessment of these stores isnessential for efficient diagnosis and research on these problems.Published methods for determining body composition in vivo appearednto be invalid for very thin cattle, frequently encountered in thentropics; the major problem was one of gross overestimation of body fat.nThere was also no objective criterion of body phosphorus status. Levelnof circulating inorganic phosphorus is subject to many sources ofnvariation, and its measurement is unsuitable for the evaluation of bodynphosphorus storage. The skeleton is the major body store of phosphorus,nbut does not appear to have been studied quantitatively with a view tonderiving an objective definition of body phosphorus status.nIn addition, recommended levels of dietary phosphorus requirementsnappeared to be excessive in relation to rates of growth of cattle grazingntropical pastures. This thesis describes three studies undertaken tonresolve these problems.(i) Estimation of the gross chemical composition of the bodynThe slaughter and analysis of 31 cattle of varied nutritionalnhistory provided data for the derivation of equations for estimatingntotal body water, fat, protein and ash from measurements of fasted livenweight and tritiated water (TOH) space. When these equations werenapplied to independent data from a further group of eight cattle, thenmean quantities of water, fat, protein and ash were estimated with annerror of less than 2%.In these eight cattle, total body water of individual animals wasnestimated from TOH space with a standard error of p2.03%, and total bodynprotein from fasted live weight with a standard error of p3.87%. Thenmost accurate method of estimating total body fat was by subtractingnfat-free weight from fasted live weight, after using the closenrelationship between total body water and fat-free weight (r = 0.996) tonestimate fat-free weight. It was shown that total body water plus totalnbody fat was virtually 80% of the total body tissues over a wide range ofnbody fatness; recalculations of data in the literature indicated thatnthis applies to a number of mammalian species.(ii) Body phosphorus status and its assessment in vivoSixteen cattle from different levels of phosphorus nutrition werenused to measure the quantities of phosphorus in the various tissues, andnthe relationships between these quantities, total body phosphorus andnlive weight. Concentrations of phosphorus in the tissues were alsonexamined in order to produce an objective criterion of body phosphorusnstatus. Phosphorus stress produced a significant decrease in thenconcentration of phosphorus in the fresh skeleton (w/w) and in itsnappendicular, axial and rib fractions. The fresh skeleton of animals fedna high phosphorus diet contained in excess of 5 g P/100 g, and that ofnphosphorus-stressed animals 4.5 g/100 g or less. Body phosphorus statusnmay therefore be objectively defined in terms of the concentration ofnphosphorus in the fresh skeleton. n n n n n n n n n n n n
TL;DR: Both TBW and fat were estimated more accurately when TOH space and live weight were used jointly and the slopes of the prediction equations for each breed were significantly different in the case of both total body water and fat.
Abstract: SUMMARY The body composition of 18 each of Mashona, Afrikaner and Hereford heifers was measured at the beginning and after 16 and 32 weeks of the experiment. The heifers not slaughtered at the beginning of the experiment were fed a complete diet containing 132 g crude protein and 12·0 MJ metabolizable energy/kg dry matter. Before slaughter, the animals were deprived of food and water for 24 h. Each animal was infused with 1 mCi of tritiated water (TOH) in order to measure total body water (TBW) and to estimate body fat. The growth rate of the three breeds of heifers was similar despite differences in age and initial live weight. Both TBW and fat proportions, however, differed significantly (P < 0·01) between slaughter stages for each breed and between breeds at each slaughter stage. At the first, second and final slaughter stages the proportions of TBW were: 68·0, 59·4 and 54·5% for Mashona; 70·;5, 64·3 and 58·3% for Afrikaner and 65·3, 57·6 and 46·2% for Hereford heifers respectively. The corresponding proportions of body fat were: 10·2, 18·4 and 24·2% for Mashona; 6·6, 12·0 and 20·0% for Afrikaner and 13·7, 20·8 and 25·8% for Hereford heifers respectively. There was a close relation between empty body weight and live weight at slaughter which was not influenced by breed. Both TBW and fat were estimated more accurately when TOH space and live weight were used jointly. However, the slopes of the prediction equations for each breed were significantly different (P < 0·05) in the case of both total body water and fat. It was necessary to use separate equations for each breed in order to predict either body water or fat. The significance of these findings for the estimation of body fat in live cattle is discussed.