The accuracy of tritiated water turnover rate as an estimate of milk intake in lambs

1979 ◽  
Vol 30 (4) ◽  
pp. 725 ◽  
Author(s):  
H Dove ◽  
M Freer

The accuracy of water turnover measurement as an estimate of milk intake was evaluated, with special reference to the validity of the assumptions underlying the technique. Even when milk was the only source of water for penned lambs, water turnover measurement significantly underestimated known milk intake. The underestimates were greater over longer measurement periods. It is suggested that these underestimates occurred because changes in body water pool size were not considered in the calculation of water turnover, since estimates were improved by the incorporation of a pool size correction. In a second pen trial, it was demonstrated that the inhalation of vapour from tritiated water excreted by other lambs was not a source of error in the estimation of water turnover. .In a field trial, the turnover technique was successfully employed to estimate milk intake in the first 3–4 weeks of life. A method for accommodating changes in pool size is presented, and it is suggested that the effects of pool size changes on the accuracy of the estimate of milk intake are too large to be ignored. In later weeks of the experiment, it was obvious that lambs were consuming water in forms other than milk, so that milk intake estimates were inaccurate. .It is concluded that in animals consuming only milk, measurement of tritiated water turnover provides an accurate estimate of milk intake, but only if changes in body water pool size are taken into account.

1988 ◽  
Vol 60 (2) ◽  
pp. 375-387 ◽  
Author(s):  
H. Dove

1. The total water turnovers of grazing ewes and their lambs were estimated on days 9, 23, 44, 69 and 86 of lactation from the dilution of tritiated water injected into the dam and deuterium oxide injected into the offspring. The contribution of milk to the total water turnover of the lambs was estimated at the same times from the accumulation of tritium in their body water.2. Mean total water turnover in the ewes was 6.5 litres/d over the entire period. In lambs, total turnover rose from 1459 ml/d at 9 d to 2791 ml/d at 86 d, and was closely related to live weight (r2 0.760, P < 0.001). The corrections to total water turnover, which were required because of the increasing body water pool size of the lambs during each measurement period, fell from +10.6% at 9 d to +3.7% at 86 d. All corrections were significant (P < 0.001).3. The intake of water as milk fell throughout the study, from 1501 ml/d at 9 d to 471 ml/d at 86 d. Pool-size corrections were significant (P < 0.001). Milk intakes calculated from these results were 1816, 1054, 862, 742 and 588 ml/d at 9, 23, 44, 69 and 86 d of lactation. The rapid decline in milk intake reflected undernutrition of the ewes in early lactation.4. The level of live-weight gain in early lactation was closely related to, and at a level expected from, the estimated milk intakes. From comparisons of estimated milk intakes with published estimates, it is concluded that the combined use of deuterium oxide and tritiated water results in accurate estimates of milk intake by the lamb throughout the ewe's lactation.


1968 ◽  
Vol 19 (1) ◽  
pp. 129
Author(s):  
PH Springell

Twenty-four steers, comprising British (Hereford and Hereford x Shorthorn), Zebu (Africander), and Zebu cross (British x Brahman or Africander) breeds, were either maintained on pasture, or yarded and fed on diets of a low and a high nutritional value. Tritiated water was injected into the animals on five occasions at intervals of 3 months. The body water content and the water turnover rate were calculated, and some of the sources of variation defined. Observed differences in the water content are attributable to nutritional factors rather than to breed differences. The mean body water content ranged from 615 to 809 ml/kg fasting body weight, where the higher values were associated with a poor diet. The mean half-life of tritiated water was lower in summer (as low as 58 hr) than in winter (up to 128 hr) in grazing and well-fed yarded steers. On a poor diet, however, the half-life in yarded cattle remained high and almost constant throughout the year, dropping to below 100 hr on only a single occasion. Occasionally the half-life was breed dependent, but generally no significant differences between breeds could be found. While mean turnover rates of up to 7.1 ml kg-1 hr-1 were found in better-fed cattle in summer, the value in poorly fed animals was almost constant throughout the year at about 3.3 ml kg-1 hr-1. There was, however, a winter minimum in the well-fed yarded and grazing groups. The turnover rate was also influenced by breed only to a limited extent. The results are interpreted in the light of their possible significance in the adaptation to a tropical environment, and in relation to their value in predicting the body composition.


1968 ◽  
Vol 19 (1) ◽  
pp. 129
Author(s):  
PH Springell

Twenty-four steers, comprising British (Hereford and Hereford x Shorthorn), Zebu (Africander), and Zebu cross (British x Brahman or Africander) breeds, were either maintained on pasture, or yarded and fed on diets of a low and a high nutritional value. Tritiated water was injected into the animals on five occasions at intervals of 3 months. The body water content and the water turnover rate were calculated, and some of the sources of variation defined. Observed differences in the water content are attributable to nutritional factors rather than to breed differences. The mean body water content ranged from 615 to 809 ml/kg fasting body weight, where the higher values were associated with a poor diet. The mean half-life of tritiated water was lower in summer (as low as 58 hr) than in winter (up to 128 hr) in grazing and well-fed yarded steers. On a poor diet, however, the half-life in yarded cattle remained high and almost constant throughout the year, dropping to below 100 hr on only a single occasion. Occasionally the half-life was breed dependent, but generally no significant differences between breeds could be found. While mean turnover rates of up to 7.1 ml kg-1 hr-1 were found in better-fed cattle in summer, the value in poorly fed animals was almost constant throughout the year at about 3.3 ml kg-1 hr-1. There was, however, a winter minimum in the well-fed yarded and grazing groups. The turnover rate was also influenced by breed only to a limited extent. The results are interpreted in the light of their possible significance in the adaptation to a tropical environment, and in relation to their value in predicting the body composition.


1978 ◽  
Vol 26 (3) ◽  
pp. 465 ◽  
Author(s):  
SC Nicol

Water turnover rates of Tasmania devils, Sarcophilus harrisii, were measured under standardized conditions by use of tritiated water. Total body water of lactating females was lower than in non- lactating animals, while water turnover rates per kilogram were not significantly different, due to a higher rate constant for lactating animals. Mean water turnover rates were considerably higher than predicted from other marsupial studies. Statistical analysis of data from 13 species of marsupial and 27 eutherian species showed habitat to have a far greater effect on standard water turnover rate than phylogeny.


1971 ◽  
Vol 22 (2) ◽  
pp. 291 ◽  
Author(s):  
NG Yates ◽  
WV Macfarlane ◽  
R Ellis

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.


1971 ◽  
Vol 49 (4) ◽  
pp. 443-447 ◽  
Author(s):  
E. H. McEwan ◽  
P. E. Whitehead

The relation between water turnover and milk intake of five reindeer and caribou calves was determined using the tritium dilution technique. The results indicate that mean turnover rates of tritiated water of male calves from birth to 4 weeks of age increased from 1.44 to 1.65 liters per day, and that caloric intake ranged from about 3500 to 4100 kcal/day.


1981 ◽  
Vol 51 (5) ◽  
pp. 1183-1188 ◽  
Author(s):  
A. A. Degen ◽  
B. Pinshow ◽  
P. U. Alkon ◽  
H. Arnon

The use of tritiated water (TOH) to estimate total body water (TBW) and total water turnover rate was validated in chukar partridges (Alectoris chukar) and sand partridges (Ammoperdix heyi). For six chukar partridges weighing between 315 to 475 g, TOH equilibration with body fluids was less than 45 min after intramuscular or intravenous injections. Mean TOH space in eight chukar partridges was 99.8% of the mean TBW measured by desiccation with individuals ranging between 97.9 and 103.2%. TOH space best approximated TBW when TBW was calculated by using the mean body mass for a bird weighed at TOH injection and at TOH equilibration. Total water intake as estimated by TOH ranged between 90.7 and 113.3% of measured water intake in three sand and three chukar partridges, birds ranging in mass from 145 to 446 g. We conclude that the TOH method provides accurate estimations of TBW and water turnover rates in birds. For birds of up to 500-g body mass, we recommend 45 min for TOH equilibration with body fluids, and intramuscular injections of 0.05 muCi TOH/g body mass for TBW estimations and 0.1 muCi TOH/g body mass for water turnover estimations.


1977 ◽  
Vol 43 (1) ◽  
pp. 121-125 ◽  
Author(s):  
D. R. Deavers ◽  
J. W. Hudson

Water turnover rate (WTR) was determined from tritiated water (3H2O) loss in the short-tailed shrew (Blarina brevicauda), red-backed vole (Clethrionomys gapperi), and white-footed mouse (Peromyscus leucopus). When given ad libitum water at Ta of 20 degrees, B. brevicauda, C. gapperi, and P. leucopus turned over 16.2, 13.8, and 6.2 ml/day, respectively; minimum WTR was 9.9, 7.8, and 3.5 ml/day, respectively. When they were given ad libitum water at 5 degrees C, WTR was 1.4 to 1.6 times higher than at 20 degrees C. On minimum water rations, WTR at 5 degrees C was 1.7 to 1.9 times higher than at 20 degrees C. Since increases in VO2 at 5 degrees C and at 20 degrees C were of about the same magnitude, increased metabolic rates may have caused increased water requirements. Total body water (TBW) was calculated from 3H2O dilution. On minimum water rations, the three species at both Ta's showed decreases in TBW and body weight, but percent body H2O increased.


1987 ◽  
Vol 108 (3) ◽  
pp. 549-553 ◽  
Author(s):  
N. Chaiyabutr ◽  
C. Buranakarl ◽  
V. Muangcharoen ◽  
P. Loypetjra ◽  
A. Pichaicharnarong

SummaryDuring 5 h of acute heat exposure (41 °C), there were increases in the heart rate from 43±2 (S.E.) to 51 ± 1 beats/min, respiratory rate from 26±4 to 86± 16 breaths/min and rectal temperature from 38·5 ± 0·1 °C to 39·7 ± 0·2 °C. The flow rate of liquid from the rumen and body water turnover significantly increased while biological half life of chromium-51 ethylenediaminetetra-acetate in the rumen and tritiated water decreased from 12·9 ± 2·5 and 87·7 ± 6·8 h to 9·3 ± 2·0 and 49·2 ± 5·7 h respectively. An increase in blood volume during acute heat stress occurred with an increase of both plasma and cell volume. An elevation of plasma water coincided with an increase in plasma protein and glucose. There is evidence that the increase in plasma water during heat exposure came from extravascular tissue space and/or from the digestive tract.


1979 ◽  
Vol 93 (1) ◽  
pp. 71-79 ◽  
Author(s):  
J. M. King

SUMMARYField studies were made of tritiated water turnover, drinking water and dietary water intake throughout the year, in 212 animals of the following species: African buffalo, dromedary camel, zebu cow, eland, small East African goat, fringe-eared oryx, and Dorper sheep.There were significant differences (P< 0·005) in the water drunk and water turnover between species and between seasons. Furthermore the species (or season) differences were also significantly different (P< 0·005) for each season (or species). The lowest turnover rates were found in oryx, then camel, sheep, goat, eland, cow and buffalo, when expressed in ml/l0·82/day, which was the appropriate metabolic unit for these species.The restraints imposed by traditional African animal husbandry have drastically reduced the natural ability of eland to conserve body water but had much less effect on buffalo and oryx. The reason appears to be that eland is behaviourally adapted to a semi-arid environment, whereas a species like oryx is more physiologically adapted.


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