Do urinary urea nitrogen and cortisol ratios of creatinine reflect body-fat reserves in black-tailed deer?

1993 ◽  
Vol 71 (9) ◽  
pp. 1841-1848 ◽  
Author(s):  
Katherine L. Parker ◽  
Glenn D. DelGiudice ◽  
Michael P. Gillingham

Urinary ratios of urea nitrogen:creatinine and cortisol:creatinine have been used as indices of the nutritional and physiological health of cervid populations. These ratios are used to monitor temporal trends in dietary protein and (or) energy deprivation, and changes in net catabolism of endogenous protein as body-fat reserves are depleted. Over a 2-year period, we compared urine chemistries of free-ranging and captive Sitka black-tailed deer (Odocoileus hemionus sitkensis) to examine seasonal and locational differences. We also determined body composition of all deer using tritiated water. Elevated urea nitrogen and cortisol ratios of creatinine did not consistently reflect individual animal body condition as measured by declining fat content in our free-ranging animals. Instead these urinary ratios more likely reflect immediate dynamics between fat depletion, protein catabolism, and energy intake rather than long-term changes in body-fat reserves.

1993 ◽  
Vol 71 (7) ◽  
pp. 1397-1404 ◽  
Author(s):  
Katherine L. Parker ◽  
Michael P. Gillingham ◽  
Thomas A. Hanley ◽  
Charles T. Robbins

Body mass, body composition, and water transfer rates were determined over a continuous 2-year period in nine free-ranging Sitka black-tailed deer (Odocoileus hemionus sitkensis). Body masses showed a cyclical pattern, declined 14 – 31% between October and March, and were best described by a five-parameter, biologically based regression model. The amount of mass lost by black-tailed deer over winter depended on the peak body mass attained during fall. During winter, animals used 70 – 82% of their body fat and 10 – 15% of their protein reserves. Body fat was preferentially mobilized at rates 2.3 – 11.6 times higher than protein. Because of the higher energy content of fat, fat accounted for 83 – 92% of the catabolized energy. Water transfer rates varied seasonally with average summer values approximately four times those of winter; lactating deer had significantly higher rates of water transfer than nonlactating animals. Seasonal changes in all of the above parameters for wild deer were greater than those for eight deer of the same age in captivity.


1997 ◽  
Vol 75 (7) ◽  
pp. 1118-1128 ◽  
Author(s):  
Michael P. Gillingham ◽  
Katherine L. Parker ◽  
Thomas A. Hanley

We examined the within-bout and seasonal dynamics of intake rate for free-ranging tractable black-tailed deer (Odocoileus hemionus sitkensis) throughout a 2-year period. Based on log frequency analyses of 487 complete active bouts, we concluded that active bouts consisted of a series of foraging bouts separated by ~2 min of nonforaging activity. Black-tailed deer spent ~92% of their active time foraging, independent of sex or season. Dry matter intake rates varied significantly with season, from ~0.5 g/min active in winter up to 1.5 g/min in summer, but few differences were attributable to sex. The large leaf size of skunk-cabbage (Lysichiton americanum) enabled deer to attain and sustain intake rates that approached predicted theoretical Rmax values of 10–12 g dry matter/min (L.A. Shipley and D.E. Spalinger. 1992. Can. J. Zool. 70: 1743–1752). Daily dry matter intake varied from 300 g/day in winter to > 1300 g/day in summer. Deer maintained a constant intake rate throughout only one-third of all active periods; intake was reduced at the end of ~40% of-all bouts, while intake rates increased towards the end of 30% of bouts. We discuss the implications of these dynamics for sampling of incomplete bouts, which is frequently employed by observers. Finally, we discuss the importance of selected, not available, biomass in understanding the foraging intake of ungulates.


1983 ◽  
Vol 31 (5) ◽  
pp. 695 ◽  
Author(s):  
IJ Rooke ◽  
SD Bradshaw ◽  
RA Langworthy

Total body water content (TBW) and TBW turnover were measured by means of tritiated water (HTO) in free-ranging populations of silvereyes, Zosterops lateralis, near Margaret River, W.A. Birds were studied in their natural habitats during spring and summer, and compared with a vineyard population in summer. In the natural habitat TBW content was found to be 77.6% in spring, which was not significantly different from that measured in summer (78.3%). Birds in vineyards in summer, however, were dehydrated, with a TBW content of 69.4%. Calculated rates of water influx for spring, summer and summer vineyards birds were 1.44,2.20 and 0.65 ml g.day-' respectively. These water turnover rates are much higher than those of any other bird yet studied. Dehydration was marked in the vineyard birds, with a significantly lower TBW content and an average net water loss of 0.63 ml day-'. Laboratory studies showed that silvereyes have a low tolerance to sodium loading. Their tolerance is, however, quite adequate for them to drink the most concentrated free water available to them in the field. Ingestion of concentrated sugar solutions of up to 25% did not provoke an osmotic diuresis and thus cannot account for the dehydration and negative water balance of vineyard birds.


Rangifer ◽  
1996 ◽  
Vol 16 (4) ◽  
pp. 201 ◽  
Author(s):  
Ray Case

Urinary urea nitrogen to creatinine ratios, urinary Nt-methylhistidine to creatinine ratios, serum urea nitrogen concentrations (SUN mg/dl), and serum Nt-methylhistidine concentrations were compared with physical measures of body composition in adult female barren-ground caribou (Rangifer tarandus groenlandicus) from the Bathurst and Southampton Island herds during late winter. Body weight and UUC were used to estimate urinary urea nitrogen (urea-N) excretion in free ranging caribou. Only mean UUC reflected differences in fat reserves between populations. None of the biochemical indicators were directly related to body composition. However, elevated UUC were only observed in caribou with depleted fat reserves as demonstrated by low kidney fat index (KFK40) and/or reduced femur marrow fat (FMF<80). UUC greater than 0.25 were indicative of undernourished animals with depleted fat reserves. SUN and UN -MHC showed no clear relationship with fat reserves. The mean estimated daily urea-N excretion for adult female caribou in late winter was extremely low (0.11+0.01SE g urea-N/day, n=76, range=0.011-0.510). The results of my study suggest that UUC can be used to detect nutritionally stressed caribou with depleted fat reserves on lichen winter ranges.


2019 ◽  
Vol 76 (9) ◽  
pp. 1515-1527 ◽  
Author(s):  
Björn Björnsson

This study supports the hypothesis that well-fed cod (Gadus morhua) seek higher temperatures to increase growth rate, and poorly fed cod select lower temperatures to save metabolic energy. Depth and temperature of free-ranging adult cod (44–79 cm) were studied with data storage tags as part of a ranching project in an Icelandic fjord. Forage fish were regularly provided at four feeding stations where cod formed distinct “herds” (herd cod) that did not mingle much with the rest of the unconditioned cod in the fjord (wild cod). Several parameters (stomach fullness, liver index (fat reserves), condition factor, and growth rate) indicated that food intake was much greater in herd cod than in wild cod. In August, when the thermocline was well established, the herd cod remained in shallow (15–35 m) and warm water (8–10 °C), whereas the wild cod stayed in deep (80–90 m) and cold water (3–4 °C), but occasionally both groups explored depths and temperatures outside their preferred range. After vertical mixing in autumn when thermoregulation was not possible, the depth difference between the two groups decreased significantly.


2020 ◽  
Vol 101 (5) ◽  
pp. 1244-1256 ◽  
Author(s):  
Thomas R Stephenson ◽  
David W German ◽  
E Frances Cassirer ◽  
Daniel P Walsh ◽  
Marcus E Blum ◽  
...  

Abstract Bighorn sheep (Ovis canadensis) can live in extremely harsh environments and subsist on submaintenance diets for much of the year. Under these conditions, energy stored as body fat serves as an essential reserve for supplementing dietary intake to meet metabolic demands of survival and reproduction. We developed equations to predict ingesta-free body fat in bighorn sheep using ultrasonography and condition scores in vivo and carcass measurements postmortem. We then used in vivo equations to investigate the relationships between body fat, pregnancy, overwinter survival, and population growth in free-ranging bighorn sheep in California and Nevada. Among 11 subpopulations that included alpine winter residents and migrants, mean ingesta-free body fat of lactating adult females during autumn ranged between 8.8% and 15.0%; mean body fat for nonlactating females ranged from 16.4% to 20.9%. In adult females, ingesta-free body fat > 7.7% during January (early in the second trimester) corresponded with a > 90% probability of pregnancy and ingesta-free body fat > 13.5% during autumn yielded a probability of overwinter survival > 90%. Mean ingesta-free body fat of lactating females in autumn was positively associated with finite rate of population increase (λ) over the subsequent year in bighorn sheep subpopulations that wintered in alpine landscapes. Bighorn sheep with ingesta-free body fat of 26% in autumn and living in alpine environments possess energy reserves sufficient to meet resting metabolism for 83 days on fat reserves alone. We demonstrated that nutritional condition can be a pervasive mechanism underlying demography in bighorn sheep and characterizes the nutritional value of their occupied ranges. Mountain sheep are capital survivors in addition to being capital breeders, and because they inhabit landscapes with extreme seasonal forage scarcity, they also can be fat reserve obligates. Quantifying nutritional condition is essential for understanding the quality of habitats, how it underpins demography, and the proximity of a population to a nutritional threshold.


1999 ◽  
Vol 50 (7) ◽  
pp. 1171 ◽  
Author(s):  
D. M. McNeill ◽  
R. W. Kelly ◽  
I. H. Williams

The effect of ewe fatness on fetal weight at term in ewes underfed in late pregnancy was tested by minimising the confounding effect of differences between fatness groups in placental weight. Twin-bearing Merino ewes in a fat (n = 9, condition score 3.8 units) or moderate (n =9, condition score 2.9) body condition were underfed to 0.6 of their requirements for energy maintenance from Day 108 to 144 of pregnancy. The fatness groups were developed over an 80-day period prior to mating by splitting a flock into 2 groups, each of similar mean liveweight and body condition score, and then enhancing the nutrient intake of one whilst restricting that of the other to maintenance levels until mating. After mating, both groups were fed similarly until Day 108 of pregnancy in an attempt to allow the development of placentas of a similar size in each. Maternal fat and protein mobilised between Day 108 and 144 of pregnancy were calculated on a per animal basis as the difference between maternal fat and protein weights at Day 108, estimated by the tritiated water dilution technique, and at Day 144, estimated by chemical analysis of fat and protein tissue following slaughter. At slaughter, the fat ewes had placentas of a size similar to those of the leaner ewes (588 v. 507 g, pooled s.e. = 50.7, P > 0.10) but produced a total weight of fetus that was 14% heavier (6646 v. 5826 g, pooled s.e. = 257.6, P < 0.05). The fat ewes also mobilised more body fat between Day 108 and 144 (3.62 v. 2.58 kg, pooled s.e. = 0.446, P < 0.10), and maintained higher levels of non-esterified fatty acids in their plasma during late pregnancy. There was no effect of ewe fatness on the extent of protein mobilisation (0.66 v. 0.62 kg, pooled s.e. = 0.623, P > 0.10) over late pregnancy. We conclude that additional maternal fat reserves can limit the extent to which fetal growth is restricted in ewes undernourished during late pregnancy.


1996 ◽  
Vol 32 (2) ◽  
pp. 326-330 ◽  
Author(s):  
Sharon K. Taylor ◽  
Victor G. Vieira ◽  
Elizabeth S. Williams ◽  
Rupert Pilkington ◽  
Sharon L. Fedorchak ◽  
...  

1983 ◽  
Vol 101 (2) ◽  
pp. 257-264 ◽  
Author(s):  
P. R. N. Chigaru ◽  
D. H. Holness

SUMMARYThe 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.


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