Total Body Electrical Conductivity Research Articles

Maternal Lipid Metabolism Is Associated With Neonatal Adiposity: A Longitudinal Study.

Pregnancy is characterized by progressive decreases in glucose insulin sensitivity. Low insulin sensitivity resulting in hyperglycemia is associated with higher neonatal adiposity. However, less is known regarding lipid metabolism, particularly lipid insulin sensitivity in pregnancy and neonatal adiposity. Because higher maternal prepregnancy body mass index is strongly associated with both hyperlipidemia and neonatal adiposity, we aimed to examine the longitudinal changes in basal and clamp maternal lipid metabolism as contributors to neonatal adiposity. Twelve women planning a pregnancy were evaluated before pregnancy, in early (12-14 weeks), and late (34-36 weeks) gestation. Body composition was estimated using hydrodensitometry. Basal and hyperinsulinemic-euglycemic clamp glucose and glycerol turnover (GLYTO) were measured using 2H2-glucose and 2H5-glycerol and substrate oxidative/nonoxidative metabolism with indirect calorimetry. Total body electrical conductivity was used to estimate neonatal body composition. Basal free-fatty acids decreased with advancing gestation (P = 0.0210); however, basal GLYTO and nonoxidative lipid metabolism increased over time (P = 0.0046 and P = 0.0052, respectively). Further, clamp GLYTO and lipid oxidation increased longitudinally over time (P = 0.0004 and P = 0.0238, respectively). There was a median 50% increase and significant positive correlation during both basal and clamp GLYTO from prepregnancy through late gestation. Neonatal adiposity correlated with late pregnancy basal and clamp GLYTO (r = 0.6515, P = 0.0217; and r = 0.6051, P = 0.0371). Maternal prepregnancy and late pregnancy measures of basal and clamp lipid metabolism are highly correlated. Late pregnancy basal and clamp GLYTO are significantly associated with neonatal adiposity and account for ~40% of the variance in neonatal adiposity. These data emphasize the importance of maternal lipid metabolism relating to fetal fat accrual.

Pharmacological Investigation of Anti-obesity Effect of Cyperus Rotundus

According to WHO, obesity is a not unusual place fitness ailment of lipid and carbohydrate metabolism that consequences from immoderate fats accumulation in adipose tissue, liver, skeletal muscle etc. This research was focused on the development and Investigation of Anti-Obesity effect of Cyperus Rotundus in obese rats. The plant- Nagarmotha was collected from Moradabad region and authenticated by the botanist. Firstly, the calibration curve was plotted. Animals were obtained from the animal house maintained at Faculty of Pharmacy, IFTM University, Moradabad, IN. Animals were free to access pellet chow diet and water ad libitum. They were kept as per CPCSEA Guidelines for one week and kept on fasting for 24 hours prior sacrificing the rodents. The rats were divided into 6 groups, each containing 6 animals. It includes Group 1: Normal Diet Control, Group 2: High caloric Diet control (HCD), Group 3: HCD + Orlistat (5 mg/kg), Group 4: HCD + EEN (100 mg/kg), Group 5: HCD+ EEN (200 mg/kg and Group 6: HCD + EEN (300 mg/kg). Each rat was evaluated after the continuous treatments for different parameters such as body weight & food intake, Total Body Electrical Conductivity (TOBEC), blood glucose levels, oral glucose tolerance test, histopathological studies for adipose tissue and liver, RNA Extraction and Semi-Quantitative PCR Analysis and liver and kidney functions test. In results, Ethanolic Extract of Nagarmotha (EEN) at all the three doses- 100mg/kg, 200mg/kg and 300mg/kg significantly exhibited lipid lowering effects when compared to standard group treated with Orlistat and control or high calories diet animals, in all the parameters. The effects were observed in dose-dependent manner, in ascending order with increase in dose. In conclusion, it may be said that EEN is a potential anti-lipidemic agent. This research suggests to characterize and isolate the main moiety responsible for its pharmacological activity (as anti-obesity) and confirm the mode of action- at which receptor subtype binding occurs.

Thomas H. Kunz

Thomas H. Kunz

Flight Performance of Migrating Juvenile Barn Swallows Hirundo rustica in Relation to Fat Load and Wing Morphology

Migratory birds have evolved the ability to accumulate fat reserves to fuel their migratory journeys. However, increased fuel load leads to an increased body mass, which is expected to impair flight performance and increase predation risk. Results of previous research are contradictory, with some studies reporting detrimental effects of fat load on flight performance, while others showing no such influences. Furthermore, no studies have investigated the relationship between fat load and flight performance in obligate aerial insectivores, which are known to accumulate only moderate fat loads while migrating overland and not crossing wide ecological barriers such as oceans or deserts. In this study we investigated the inter-individual variation in short-term flight performance (flight manoeuvrability, velocity and acceleration) in juvenile Barn Swallows Hirundo rustica in relation to fat load in Poland (central Europe), during the initial stages of autumn southward migration. We evaluated individual swallow fat loads by means of a Total Body Electrical Conductivity (TOBEC) scanner. In order to evaluate short-term flight performance in a standardised manner we used flight tunnels. We controlled statistically for the independent effect of wing morphology, which can be expected to influence flight performance. Juvenile fat loads were on average 7.5% (range 0.2–20.5) of lean body mass, but we found no negative effect of the fat mass on short-term flight performance traits. Individuals with larger fat mass reached higher velocity compared to leaner ones, which is in line with theoretical expectations. However, fat mass did not significantly predict flight manoeuvrability or acceleration. The results indicate that relatively small fat loads accumulated by juvenile Barn Swallows during overland migration do not impair short-term flight performance.

Body mass as an estimate of female body condition in a hibernating small mammal

In hibernating squirrels, the amount of energy stored as fat may influence several important demographic traits, but is difficult to quantify in living animals. Thus, several non-destructive indices of body condition are used, including simple indices that use body mass and scaled indices that correct body mass for structural size. However, the accuracy of these indices for hibernating squirrels is poorly known. We used measurements of total body electrical conductivity (TOBEC) from adult female Golden-mantled Ground Squirrels (Callospermophilus lateralis) to characterize body composition (lean mass versusfat mass) and condition (fat stores) at multiple stages in the circannual cycle. Body mass explained a high proportion of the variation in fat mass during the emergence and pre-hibernation stages, but less during the reproduction stage. Contrary to expectation, correcting for structural size did not markedly improve the condition index. Our results suggest that body mass is a good estimate of body condition during the periods of emergence and pre-hibernation fattening, and therefore may be useful to predict important components of fitness such as reproductive success and overwinter survival.

Restorative potentiality of S-allylcysteine against diabetic nephropathy through attenuation of oxidative stress and inflammation in streptozotocin-nicotinamide-induced diabetic rats.

In the present study, we evaluated the therapeutic potentiality of S-allylcysteine (SAC) in streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic nephropathy (DN) in experimental rats. SAC was orally administered for 45days to rats with STZ-NAD-induced DN; a metformin-treated group was included for comparison. Effect of SAC on body weight, organ weight, blood glucose, levels of insulin, glycated haemoglobin, and renal biochemical markers was determined. Body composition by total body electrical conductivity (TOBEC) and dual-X ray absorptiometry (DXA), kidney antioxidant analysis, real-time polymerase chain reaction, and western blot analysis of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), nuclear factor kappa B (NF-κB), interleukin (IL)-6, and tumor necrosis factor (TNF)-α; histopathological and scanning electron microscope (SEM) analysis of the kidneys were performed in both control and experimental rats. SAC treatment showed significantly decreased levels of blood glucose, glycated haemoglobin, creatinine, albumin, AST, ALT, creatinine kinase, lactate dehydrogenase, and expressions of NF-κB, IL-6, and TNF-α compared with DN control rats. Furthermore, SAC administration to DN rats significantly improved body composition and antioxidant defense mechanism which was confirmed by the upregulation of mRNA and protein expressions of antioxidant genes. Thus, SAC showed adequate therapeutic effect against DN by downregulation of inflammatory factors and attenuation of oxidative stress. Histological and SEM observations also indicated that SAC treatment notably reverses renal damage and protects the kidneys from hyperglycemia-mediated oxidative damage.

Energy balance and body reserves in rabbit females selected for longevity

<p>The aim of this study was to compare the energy balance and dynamic of body reserves in rabbit females divergently selected for longevity. One hundred and twenty-nine females from a high longevity line (HL) and 131 females of a low longevity line (LL) were studied from the 1<sup>st</sup> to the 3<sup>rd</sup> kindling. Litter size and weight and female body weight were measured at kindling (1<sup>st</sup>, 2<sup>nd</sup> and 3<sup>rd</sup>), insemination (2<sup>nd</sup> and 3<sup>rd</sup>) and at weaning (1<sup>st</sup> and 2<sup>nd</sup>). The total body electric conductivity (TOBEC) method was used to estimate the body reserves in all females at artificial insemination and at weaning, and at kindling in females that achieved parturition. Energy balance between the 11<sup>th</sup> and the 21<sup>th</sup> d of lactation was also calculated for these females. No significant difference was found for fertility or for the number of offspring born alive and weaned. However, the total number of offspring born was higher in the LL line than in the HL line at the 2<sup>nd</sup> parturition (+1.12±0.46 g; P<0.05). Consequently, the number of stillborn offspring was higher in the LL line. LL females were 4% heavier than HL females at the first parturition (P<0.05), but then HL females had a higher live weight gain than LL females from the 1st parturition to the 2<sup>nd</sup> artificial insemination (+107.0±29 g; P=0.049), leading to a similar weight between the lines at the 2<sup>nd</sup> artificial insemination. There was no significant difference between lines for estimated energy used for growth between the 11<sup>th</sup> and the 21<sup>th</sup> d of lactation, or for estimated milk production (2365±30 g in HL line vs. 2398±30 g in LL line), estimated using the weight gain of the kits between the 11<sup>th</sup> and 21<sup>st</sup> d of lactation, for feed intake measured during this period (351±5 g/d in HL line vs. 359±5 g/d in LL line) or for energy balance (–6.11±0.3 MJ in HL line vs. –6.30±0.3 MJ in LL line). However, body energy content was higher in HL females than in LL (+2.72±0.64 MJ; P=0.001). In conclusion, selection for higher functional longevity results in a better ability of females to use body reserves in their early reproductive life.</p>

Total Body Electrical Conductivity for Determining Carcass Fat in Ruffed Grouse

Percent carcass fat is often considered a primary condition indice in game bird species. Although regarded as the standard for determining fat reserves, traditional sampling methods require sacrificing animals for chemical analysis via fat extraction. Lethal methods negate the ability to track condition of individuals through time. Avian physiology studies often require the assessment of conditional changes through time and among various treatments, which necessitate the use of a non-lethal method for estimating fat levels. We were able to accurately estimate fat condition in captive ruffed grouse (Bonasa umbellus) utilizing total body electrical conductivity (TOBEC). We developed predictive models to estimate percent carcass fat directly from first-order regression of TOBEC and body mass values. Validation of our best model from an independent sample (n = 10 individuals) produced an R2 = 0.85(P < 0.001) for determining percent carcass fat and R2 = 0.89(P < 0.001) for determining total fat mass in ruffed grouse. Future studies investigating galliform ecology or physiology could benefit from use of TOBEC for assessment of fat condition if non-lethal sampling is desired to track changes through time.

Longitudinal changes in infant body composition: association with childhood obesity.

Rapid weight gain in infancy has been established as a risk factor for the development of later obesity. We aimed to investigate the role of changes in infant body composition (assessed via total body electrical conductivity) on the development of overweight/obesity in mid-childhood. Fifty-three term infants were evaluated at birth, three times during infancy and in mid-childhood. Logistic regression was used to determine associations between rates of total weight gain, fat mass gain and lean mass gain during infancy and later overweight/obesity (defined as body mass index [BMI] ≥85th percentile), adjusted for birth weight and parent education. At follow-up (age 9.0 ± 1.8 years), 30% were overweight/obese. More rapid total weight gain from 0 to 4 months was associated with twofold odds (odds ratio [OR] 1.98, 95% confidence interval [CI] 1.05-3.74, P = 0.04) of overweight/obesity in mid-childhood. From 0 to 8 months, more rapid weight gain was associated with nearly fivefold odds (OR 4.76, 95% CI 1.05-21.5, P = 0.04), and more rapid fat mass gain was associated with eightfold odds (OR 8.03, 95% CI 1.11-58.2, P = 0.04) of later overweight/obesity. This exploratory study suggests that rapid weight gain, especially fat mass gain, in earlier infancy predisposes to mid-childhood overweight/obesity.

Validade dos métodos para avaliação da gordura corporal em crianças e adolescentes por meio de modelos multicompartimentais: uma revisão sistemática

ObjectiveTo analyze the validity of methods to assess body fat in children and adolescents using a systematic review. MethodsThe search was conducted by two independent researchers using the MEDLINE, BioMed Central, SciELO and LILACS electronic databases. For inclusion, the articles should be written in English or Portuguese, and must have used multi-compartment models as the criterion measure of the model, with body fat measurement of whole body in non-athlete children and adolescents. ResultsA preliminary search resulted in 832 studies. After all selection steps were performed, 12 articles were included. The selected studies were published between 1997 and 2010, whose samples consisted of children and adolescents with levels of relative body fat ranging from 20.7% to 41.4%. The methods used were: dual energy X-ray absorptiometry (58.3%), isotope dilution (41.6%), skinfold thickness (33.3%), hydrostatic weighing (25%), bioelectrical impedance analysis (25%), air displacement plethysmography (16.6%), and total body electrical conductivity (8.3%). ConclusionsBased on the analysis of the studies, isotope dilution and air displacement plethysmography methods were the most reliable, despite the limited number of studies. As for clinical use or for population-based studies, the equation of Slaughter et al. (1998), wich uses the triceps and subscapular skinfolds thickness, showed the best results for assessment of body fat in this population.

Non-destructive techniques to assess body composition of birds: a review and validation study

Body composition of birds is often used to assess in part the ''condition'' of individuals in the context of their life history and ecology. We describe contemporary non-destructive (non-lethal) techniques that are available for estimating the body composition of free-living birds. We critically evaluate the strengths and weaknesses of these techniques in the context of bird studies. Although most contemporary techniques are based on theory and first principles, assessing their accuracy and precision requires empirical calibrations. We summarize the results of recent validation studies on songbirds and discuss their implica- tions. Deuterium dilution was the best single technique among those compared for measuring lean and fat dynamics in small songbird species that averaged 9-29 g, although we advocate technique(s) that independently estimate each body component. Interspecific models that estimated lean mass using total body electrical conductivity and structural measure(s), and estimated fat mass using deuterium dilution were as accurate (within 0.3-1.1 g of actual lean mass and 0.2-0.9 g of actual fat mass, respec- tively, depending on bird species) as intraspecific models for songbirds that averaged 13-29 g in body mass. Thus, separate models for each bird species may not be neces- sary, and the development and testing of interspecific models for estimating body composition is warranted. Several factors, including body size and physiological state, required accuracy and precision, and the scope of predictions must be carefully considered when any of these non-destructive techniques are used to measure the body composition of birds.

Validity of the methods to assess body fat in children and adolescents using multi-compartment models as the reference method: a systematic review

ObjectiveTo analyze the validity of methods to assess body fat in children and adolescents using a systematic review. MethodsThe search was performed by two independent researchers using the MEDLINE, BioMed Central, SciELO, and LILACS electronic databases. For inclusion, the articles should have been written in English or Portuguese, and must have used multi-compartment models as the criterion measure of the model, with body fat measurement of the whole body in non-athlete children and adolescents. ResultsA preliminary search resulted in 832 studies. After all selection steps were performed, 12 articles were included. The selected studies were published between 1997 and 2010, whose samples consisted of children and adolescents with levels of relative body fat ranging from 20.7% to 41.4%. The methods used were: dual energy X-ray absorptiometry (58.3%), isotope dilution (41.6%), skinfold thickness (33.3%), hydrostatic weighing (25%), bioelectrical impedance analysis (25%), air displacement plethysmography (16.6%), and total body electrical conductivity (8.3%). ConclusionsBased on the analysis of the studies, isotope dilution and air displacement plethysmography methods were the most reliable, despite the limited number of studies. As for clinical use or for population-based studies, the equation of Slaughter et al. (1988), which uses the triceps and subscapular skinfold thickness, showed the best results for assessment of body fat in this population.

Alteration in body composition in the portacaval anastamosis rat is mediated by increased expression of myostatin.

The portacaval anastamosis (PCA) rat is a model to examine nutritional consequences of portosystemic shunting in cirrhosis. Alterations in body composition and mechanisms of diminished fat mass following PCA were examined. Body composition of male Sprague-Dawley rats with end-to-side PCA and pair-fed sham-operated (SO) controls were studied 3 wk after surgery by chemical carcass analysis (n=8 each) and total body electrical conductivity (n=6 each). Follistatin, a myostatin antagonist, or vehicle was administered to PCA and SO rats (n=8 in each group) to examine whether myostatin regulated fat mass following PCA. The expression of lipogenic and lipolytic genes in white adipose tissue (WAT) was quantified by real-time PCR. Body weight, fat-free mass, fat mass, organ weights, and food efficiency were significantly lower (P < 0.001) in the PCA than SO rats. Adipocyte size and triglyceride content of epididymal fat in PCA rats were significantly lower (P < 0.01) than in SO rats. Myostatin expression was higher in the WAT of PCA compared with SO rats and was accompanied by an increase in phospho-AMP kinase Thr(172). Follistatin increased whole body fat and WAT mass, adipocyte size, and expression of lipogenic genes in WAT in PCA, but not in SO rats. Myostatin and phospho-AMP kinase protein and lipolytic gene expression were lower with follistatin. We conclude that PCA results in loss of fat mass due to an increased expression of myostatin in adipose tissue with lower lipogenic and higher fatty acid oxidation gene expression.

Prediction of body composition by total body electrical conductivity technique is affected by fat reserves of Japanese quail

The effect of fat accumulation on the prediction of in vivo body composition by a total body electrical conductivity (TOBEC) technique was evaluated using Japanese quail at 2 life periods (0 to 21 d and 28 to 70 d of age) that differ significantly in the fatness of birds. In total, 119 quail of 14 age categories were weighed and scanned by the TOBEC analyzer, and their carcasses were subjected to chemical analysis. The prediction equations for chemical composition (percentage of water, lipids, and lean tissue) and body masses (weight of body, water, lipids, and lean tissue) were obtained by linear regression analysis. The equations involved the E-value as the independent variable. In both growth phases, a high accuracy of estimation was found for the total body, lean, and water masses (0.85 ≤ R(2) ≤ 0.98), whereas a low accuracy of estimation was observed for percentages of lipids, lean tissue, and water (0.27 ≤ R(2) ≤ 0.64). Most of the variables showed a worse estimation in the late than in the early growth phase; the maximum difference was observed for the lipid mass (R(2) = 0.35 vs. 0.90, respectively). The correlations between analyzed variables and the residual error distributions of regression models demonstrated that the lower power of the models in the late versus early growth phase may be attributed to an enhanced fat accumulation in sexually mature birds. Their high fat reserves considerably decrease body hydration, which negatively influences the estimation of body composition based upon the TOBEC procedure.

Effect of egg composition on hatchability and on growth and slaughter characteristics of meat-type chicks

1. Using the so-called TOBEC (Total Body Electrical Conductivity) method, which allows the determination of egg composition in vivo, correlations between egg composition, hatchability and hatched chicks’ development were studied. 2. A total of 1500 hen eggs (Ross-308) were measured by TOBEC, and eggs with extremely high (10%, n = 150), extremely low (10%, n = 150) and average (10%, n = 150) electrical conductivity values were chosen for further investigation. 3. During the incubation period, it was observed that eggs with high electrical conductivity had a significantly higher mortality than eggs with low electrical conductivity. 4. It was observed that both the increase in electrical conductivity at the same egg weight, and the increase in egg weight at the same electrical conductivity resulted in an increase in the hatching weight. 5. It was found that the dry matter, protein and fat content of the chicks hatched from eggs with low electrical conductivity was higher at hatching than that of the chicks hatched from eggs with high electrical conductivity. 6. At 42 d of age the liveweight of cocks and pullets hatched from eggs with low electrical conductivity was 3·2 and 8·2% higher than the liveweight of cocks and pullets hatched from eggs with high electrical conductivity. 7. Because of the higher liveweight at slaughter, there was a significant superiority of the chicks hatched from eggs with low electrical conductivity in the case of the examined carcase traits at slaughter. 8. Similar tendencies were found also in the ratios of carcase variables to liveweight, but the between group differences were not statistically significant in this case. 9. Based on the results it was concluded that TOBEC seems to be a useful method for separating eggs with different composition. 10. This could be a good starting point for further in vivo investigations in order to clarify the effect of egg composition on hatchability and further development.

Evaluation of Total Body Electrical Conductivity to Estimate Body Composition of a Small Mammal

ABSTRACT The ability to measure body composition is critical for studying the physiological ecology of animals. This is particularly true for small mammals that have a high metabolic rate. We evaluated a nondestructive method of body composition analysis that would allow accurate assessment of body fat, body water, and lean mass. We used total body electrical conductivity (TOBEC) to estimate body composition in the little brown myotis (Myotis lucifugus). In a sample of 46 individuals, TOBEC was both accurate and precise in estimating total body water and lean mass but was less effective at estimating total body fat. Mass‐independent or whole‐body compartments (i.e., total body water, total body fat, lean dry mass, and lean body mass) were more accurately estimated than mass‐dependent or mass‐specific body composition compartments (i.e., water content, fat index, and % lean dry mass). The TOBEC measurements we made using an SA‐3000 analyzer were influenced by extremes in body temperature, as well as by aluminum and incoloy wing bands. Our study also presents a new method of restraint especially suited for small mammals and birds that increases precision of TOBEC measurements. This study shows that TOBEC is a potentially valuable tool for studying changes in body composition of small mammals and may provide insight into the physiological impacts of various life history stages such as postnatal growth, reproduction, and hibernation.

Neonatal adiposity following maternal treatment of gestational diabetes with glyburide compared with insulin

We hypothesized that body composition would be similar among neonates of women with gestational diabetes (GDM) treated with glyburide or insulin. Women with GDM requiring medical therapy were randomized to insulin or glyburide. The primary outcome was percent neonatal fat mass measured by total body electrical conductivity. Secondary outcomes included anthropometrics, glycemic control, and biomarkers. Statistical analysis included Student t test, chi(2), and regression modeling. Eighty-two neonates underwent postnatal measurements. Baseline factors were not different by group. Neonatal percent fat mass did not differ between treatment groups (11.2 +/- 4.2 vs 12.8 +/- 5.7). Fat mass, body mass index, ponderal index, skinfold sum, and arm fat area were not different when analyzed by intent to treat or actual treatment group. Cord concentrations of biomarkers were also similar. There was no difference in neonatal adiposity in infants of women treated for GDM with glyburide or insulin.

Comparison of the slaughter characteristics of meat-type chicks hatched from eggs with different composition

Using the so-called TOBEC (Total Body Electrical Conductivity) method for the in vivo determination of egg composition, the effect of egg composition on the slaughter characteristics of hatched chicks was examined in the ROSS-308 meat-type genotype. Chicks hatched from eggs with low, average and high electrical conductivity were slaughtered at 42 days of age. It was found that the weight of all of the examined traits showed highest values in the case of chicks hatched from eggs with low electrical conductivity, while the lowest values could be observed in the case of chicks hatched from eggs with high electrical conductivity. Similar tendencies were observed also in the case of the ratio of the examined slaughter traits to the slaughter weight, but in this case the differences were not statistically proven (P>0.05).

Estimating lipid and lean body mass in small passerine birds using TOBEC, external morphology and subcutaneous fat‐scoring

To assess regression models for lipid and lean body mass in small birds, we recorded live body mass ±0.1 g, total body electrical conductivity (TOBEC; from “third generation” TOBEC machine EM‐SCAN® SA‐3000) or E‐Value, visual fat score (VisFat), and seven body measurements for 52 migratory passerine birds of 13 species (5–40 g). We determined lipid and lean mass of each bird after petroleum‐ether extraction of lipids. We obtained “net”E‐Value (NEV) for each scanned bird by subtracting the E‐Value of the empty bird‐restraining tube, because these showed an inverse temperature dependence (P&lt;0.005). Leave‐one‐out cross validation was used to assess model selection and construct 95% confidence intervals. Although precision of TOBEC increased with bird size (CV of NEV vs. live mass: r=−0.276, P=0.002) and it explained an increasing proportion of variation in lean mass moving from small‐ to medium‐ to large‐bird classes of our data, it did no better than head length in single‐variable prediction of lean or lipid mass and was included in five of the 14 multivariate models we developed. The best multiple regression to predict lean mass included live weight, VisFat, bill length, tarsus and lnNEV (adjusted R2=99.0%); however, the same model lacking only lnNEV yielded aR2=98.9%. A parallel to the above pair of models, but predicting lipid mass, yielded aR2=90.3% and 90.0%, respectively. Subdividing the data by three size classes and three taxa (American redstart Setophaga ruticilla, ovenbird Seiurus aurocapilla, warblers), best‐subset multiple‐regression models predicted lean mass with aR2 from 94.7 to 99.6% and lipid mass with aR2 from 85.4 to 98.3%. Best models for the size‐ and species‐groups included VisFat and zero to five body measurements, and most included live weight. lnNEV was included only in the models for ovenbird (lipid), warblers (lipid), all birds (both), and large birds (both). Actual lipid mass of all birds was more highly correlated with multiple‐regression‐predicted lipid mass (r=0.955) than with visual subcutaneous fat‐scoring (r=0.683). These multiple‐regression models predicting lipid content using live‐bird measurements and visual fat score as independent variables represent more accurate and precise estimates of actual lipid content in small passerines than any previously published. They are particularly accurate for placing birds into percentage body‐fat classes.

Evaluation of morphological indices and total body electrical conductivity to assess body composition in big brown bats

Bat researchers have used both morphological indices and total body electric conductivity (TOBEC) as proxies for body condition in a variety of studies, but have typically not validated these indices against direct measurement of body composition. We quantified body composition (total carcass lipids) to determine if morphological indices were useful predictors of body condition in big brown bats (Eptesicus fuscus). We also evaluated body composition indirectly by TOBEC using EM-SCAN® technology. The most important predictors of body composition in multiple regression analysis were body mass-to-forearm ratio (partial r 2 = 0.82, P < 0.001) followed by TOBEC measurement (partial r 2 = 0.08, P < 0.001) and to a minor extent head length (partial r 2 = 0.02, P < 0.05). Morphological condition indices alone may be adequate for some studies because of lower cost and effort. Marking bats with passive integrated transponder (PIT) tags affected TOBEC measurements.