DIFFERENTIAL GROWTH AND BODY COMPOSITION IN ALTRICIAL PASSERINES

The differential development of various body organs and of fat, water, and other constituents was studied in three species with altricial nestlings—Blue Tit, House Martin and House Sparrow.
In all species resources available at each stage of the nestling period were allocated to those components of most use to the nestlings at the time, although due regard was paid to future needs. Components associated with the ingestion and assimilation of food, such as the mouth, gizzard, intestine and liver, developed early in the nestling period whilst locomotory components, such as wings and pectoral muscles, developed late. Similarly, body plumage needed for insulation developed ahead of the locomotory remiges and rectrices, but only after much of the nestlings' growth in size had been completed.
The water index (water content/lean dry weight) provided a consistent index of tissue and nestling maturity amongst young of different nutritional status. This index was very similar for all three species when age was expressed as a fraction of the nestling period.
Both absolute fat content and the fat index (fat content/lean dry weight) increased with age. The adaptive value of these trends and of interspecific differences in fat index is discussed.
The results are seen as consistent with both the physiological bottleneck models of avian growth rates. It is suggested that the growth patterns of birds may be dominated more by ecological considerations affecting all aspects of the development mode than by internal physiological constraints affecting growth rates alone.     

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.     

Body-Mass, Composition, and Survival of Nestling and Fledgling Starlings (

Earlier studies of the starling (Sturnus vulgaris) population at Belmont, Lower Hutt, New Zealand, showed that nest productivity was low compared with other populations in New Zealand and elsewhere. Therefore, we investigated possible trade-offs between offspring number and quality (as measured by body mass and composition). We also compared these measures of offspring condition with pre- and post-fledging survival. Nestling mass did not significantly differ with clutch size or brood size at any age. In starlings about to leave the nest, lean (i.e., fat-free) dry mass and water mass increased with body mass, but lipid mass increased approximately twice as much. When the effects of the other variables were controlled in a partial correlation analysis, lean dry mass, water mass, lipid mass, and mass of stomach contents were positively correlated with mass at nest-leaving; brood size was not correlated with mass at nest-leaving. Nest success was independent of clutch size and brood size, but lighter broods were more likely to fail totally than were heavier broods early in the nestling period. Nestling survival early, but not late, in the nestling period was positively correlated with nestling mass. The likelihood that a nestling raised in 1973-1979 would be recruited as a breeder was independent of its mass at brood- day 12. Thus, unlike some other passerines, larger, heavier starling nestlings did not seem to survive better than average ones. Low productivity was not accompanied by a decrease in body condition of those nestlings that survived the nestling period. Therefore, starlings at Belmont reduced offspring number rather than offspring quality when they encountered unfavourable conditions.     

Evaluating indices of body condition in two cricket species

Body mass components (dry mass, lean dry mass, water mass, fat mass) in each sex correlate strongly with body mass and pronotum length in Gryllus texensis and Acheta domesticus. Ordinary least squares (OLS) regression underestimates the scaling relationship between body mass and structural size (i.e., pronotum length) in both cricket species compared with standard major axis (SMA) regression. Standardized mass components correlate more strongly with scaled mass index () than with residual body mass (R_i). R_i represents the residuals from an OLS regression of log body mass against log pronotum length. Neither condition index predicts energy stores (i.e., fat content) in G. texensis. R_i is not correlated with energy stores in A. domesticus whereas is negatively correlated. A comparison of condition index methods using published data showed that neither sex nor diet quality affected body condition at adulthood in G. texensis when using the scaled mass index. However, the residual index suggested that sex had a significant effect on body condition. Further, analysis of covariance (ANCOVA) suggested that diet quality significantly affects body mass while statistically controlling for body size (i.e., body condition). We conclude that the statistical assumptions of condition index methods must be met prior to use and urge caution when using methods that are based on least squares in the y‐plane (i.e., residual index ANCOVA).     

Lipid reserves,fasting capability and the evolution of nestling obesity in procellariiform seabirds

Several alternative explanations have been proposed to account for the evolution of nestling obesity in a variety of avian groups. These predict quite different patterns of fat accumulation, storage and use by chicks of different ages. Yet surprisingly few studies have measured changes in body composition during chick development. We tested the applicability of these hypotheses for fulmars, Fulmarus glacialis, by direct measurement of changes in water, lipid and lean dry mass in growing chicks. Lipid and lean dry mass increased until ca. 70% of the way through chick rearing, but then levelled off. Total body water also increased until the same stage, but gradually declined thereafter, and it was this change rather than fat metabolism that resulted in mass recession. The observed pattern of a continued increase in stored lipid, and most importantly, its maintenance all the way through the mass-recession phase until chicks reach fledging, is incompatible with many of the proposed hypotheses. We suggest that the most likely ultimate explanation for large fat deposits is to fuel chicks during the initial critical period away from the nest site while they learn to forage     

The individual age at menopause — An appropriate indicator of postmenopausal body composition?

The interaction between age at menopause and postmenopausal body composition development was tested with in 178 Viennese women aged 47 to 68 years (x=55.4 yr). Postmenopausal body composition was described using dual energy x-ray absorptiometry by absolute fat and lean mass and bone mineral content of the whole body, the arms, legs, the trunk and the head. Upper and lower amount of body fat, the fat percentages of the individual body compartments and the fat distribution index were calculated. Postmenopausal body fat and lean soft tissue mass and postmenopausal bone mineral content were significantly associated with the age at menopause. Women whose menopause occurred late showed the highest amount of body fat (31.2+/−7.7kg) and lean body mass (41.2+/−4.4 kg) postmenopausally, while women with an early menopause exhibited the lowest amount of body fat (27.5+/−8.9kg) and lean body mass (38.4+/−5.4 kg) during the postreproductive phase of life (p<0.05). Women whose menopause occurred later than 51 had a significant higher postmenopausal bone mass (2.26+/−0.9kg versus 2.09+/−0.3 kg; p<0.05). A late menopause was associated with a significantly higher value in fat mass, lean body mass and in bone mineral content. Therefore age at menopause may be assumed as an indicator for body fat and bone mineral content during postmenopause and postmenopausal fat distribution patterns.     

Non-invasive measure of body composition of snakes using dual-energy X-ray absorptiometry

Non-invasive techniques to measure body composition are critical for longitudinal studies of energetics and life histories and for investigating the link between body condition and physiology. Previous attempts to determine, non-invasively, the body composition of snakes have proven problematic. Therefore, we explored whether dual-energy X-ray absorptiometry (DXA) could be used to determine the body composition of snakes. We analyzed 20 adult diamondback water snakes (Nerodia rhombifer) with a DXA instrument and subsequently quantified their body composition by gravimetric and chemical extraction methods. Body composition components scaled with body mass with mass exponents between 0.88 and 1.53. DXA values for lean tissue mass, fat mass and total-body bone mineral mass were significantly correlated with observed masses of lean tissue, fat and ash from chemical analysis. Using regression models incorporating DXA values we predicted the fat-free tissue mass, lean tissue mass, fat mass, ash mass and total body water content for this sample of water snakes. A cross-validation procedure demonstrated that these models estimated fat-free tissue mass, lean tissue mass, fat mass, ash mass and total-body water content with respective errors of 2.2%, 2.3%, 16.0%, 6.6% and 3.5%. Compared to other non-invasive techniques, include body condition indices, total body electrical conductivity (TOBEC) and cyclopropane absorption, DXA can more easily and accurately be used to determine the body composition of snakes.     

Assessment of body condition of harp seals

We investigated the relationships between blubber content and a suite of condition indices in harp seals (Phoca groenlandica). Although blubber content was significantly correlated with xiphosternal blubber depth and Condition index they were insensitive indicators of condition. Blubber depth was most variable at a site ca. 60–70% down the length of the body and a more recent index incorporating length, mass and blubber depth devised for phocids was an improved indicator of blubbler mass. Blubber volume was calculated in three ways based on a geometric approximation of a cylinder and also via truncated cones. The cone method accounted for more variance than the other methods although it overestimated blubber mass. Surface area was ascertained using the girth measurements of serial cones and was significantly correlated with total body mass and total body water. We suggest that estimates of total body water generated from surface area could be used to calculate total fat mass and lean body mass     

湖南土家族成人的皮褶厚度和体成分分析

本项目采用人体测量法,测量了976名（男性528人,女性448人）湖南土家族成人的身高、体质量以及肱三头肌、肩胛下、髂前上和小腿内侧皮褶的厚度,并根据公式计算体密度、体脂率、脂肪质量、脂肪质量指数、瘦体质量和瘦体质量指数。结果显示随年龄增长,小腿内侧皮褶厚度值逐渐减小,肱三头肌、肩胛下和髂前上棘皮褶以及体脂率、脂肪质量、瘦体质量、体质量指数、脂肪质量指数和瘦体质量指数值先增大后减小,体密度值先减小后增大;各年龄组中体密度、瘦体质量及其指数值女性明显低于男性,4项皮褶厚度值以及体脂率、脂肪质量及其指数值女性高于男性;与布朗族等24个族群比较,湖南土家族成人皮褶厚度处于中等水平,与门巴族、珞巴族、僜人、彝族等族群的亲缘关系较近。     

Dual Energy X-Ray Absorptiometry Body Composition Reference Values from NHANES

In 2008 the National Center for Health Statistics released a dual energy x-ray absorptiometry (DXA) whole body dataset from the NHANES population-based sample acquired with modern fan beam scanners in 15 counties across the United States from 1999 through 2004. The NHANES dataset was partitioned by gender and ethnicity and DXA whole body measures of %fat, fat mass/height², lean mass/height², appendicular lean mass/height², %fat trunk/%fat legs ratio, trunk/limb fat mass ratio of fat, bone mineral content (BMC) and bone mineral density (BMD) were analyzed to provide reference values for subjects 8 to 85 years old. DXA reference values for adults were normalized to age; reference values for children included total and sub-total whole body results and were normalized to age, height, or lean mass. We developed an obesity classification scheme by using estabbody mass index (BMI) classification thresholds and prevalences in young adults to generate matching classification thresholds for Fat Mass Index (FMI; fat mass/height²). These reference values should be helpful in the evaluation of a variety of adult and childhood abnormalities involving fat, lean, and bone, for establishing entry criteria into clinical trials, and for other medical, research, and epidemiological uses.     

Nutritional Status of Maintenance Dialysis Patients: Low Lean Body Mass Index and Obesity Are Common,Protein-Energy Wasting Is Uncommon

Background and Aims

Maintenance dialysis patients are at increased risk of abnormal nutritional status due to numerous causative factors, both nutritional and non-nutritional. The present study assessed the current prevalence of protein-energy wasting, low lean body mass index and obesity in maintenance dialysis patients, and compared different methods of nutritional assessment.

Methods

In a cross-sectional study conducted in 2014 at Roskilde Hospital, Denmark, we performed anthropometry (body weight, skinfolds, mid-arm, waist, and hip circumferences), and determined plasma albumin and normalized protein catabolic rate in order to assess the prevalence of protein-energy wasting, low lean body mass index and obesity in these patients.

Results

Seventy-nine eligible maintenance dialysis patients participated. The prevalence of protein-energy wasted patients was 4% (95% CI: 2–12) as assessed by the coexistence of low lean body mass index and low fat mass index. Low lean body mass index was seen in 32% (95% CI: 22–44). Obesity prevalence as assessed from fat mass index was 43% (95% CI: 32–55). Coexistence of low lean body mass index and obesity was seen in 10% (95% CI: 5–19). The prevalence of protein-energy wasting and obesity varied considerably, depending on nutritional assessment methodology.

Conclusions

Our data indicate that protein-energy wasting is uncommon, whereas low lean body mass index and obesity are frequent conditions among patients in maintenance dialysis. A focus on how to increase and preserve lean body mass in dialysis patients is suggested in the future. In order to clearly distinguish between shortage, sufficiency and abundance of protein and/or fat deposits in maintenance dialysis patients, we suggest the simple measurements of lean body mass index and fat mass index.     

On the importance of fat reserves for the little auk (Alle alle) chicks

Summary The pattern of fat deposition and inter-year variation in the amount of deposited fat, lean dry mass (LDM) and water were studied in the chicks of little auk (Alle alle), an arctic alcid, at Spitsbergen in the 1984, 1986 and 1987 breeding seasons. The lipid index (lipid mass/LDM) rose from 0.29 at hatching to about 0.70 at the age of maximum body mass attained in the nest, the highest yet recorded for seabirds except procellariiforms. Just before fledging the index dropped to 0.38. Fat mass in 1984 chicks and also fresh body mass of older 1984 chicks was significantly lower than in the other two seasons, but there were no statistical year-to-year differences in LDM's of chicks. The amount of fat in chicks was significantly correlated with certain weather parameters. Fasting capability (FC) of the chicks (the time that chicks could survive when using only their lipid stores) was calculated from fat mass and previous data on metabolic rates of chicks. The FC's of all 108 chicks collected in three seasons were greater than maximum interval between two consecutive feeds to chicks reported in the study colony. Also the estimated fat reserves of 99.7% of chicks weighed in 1984 were sufficient to support them for longer than the maximum recorded intervals between feeds. In relation to death by starvation, little auk chicks, at least up to the age of maximum body mass, have a substantial surplus of fat. This is contrary to the hypothesis that fat depots in seabird chicks assist survival during the periodic fasts resulting from unpredictable feeding conditions.     

Variation in body condition of breeding Savi’s Warblers Locustella luscinioides: the reproductive stress and flight adaptation hypothesis revisited

Current theory suggests that mass change in adult birds while breeding may be adaptive (to reduce wing-loading during nestling feeding) or result from physiological stress. To test which might be more important in determining mass loss in breeding Savi’s Warblers (Locustella luscinioides), we used a new approach in which the variation in four indices of body condition was described: weight, fat score, muscle score and lean weight (i.e. excluding fat and muscle). We expected weight variations to be adaptive if they involved changes in fat and lean weight, whereas physiological stress should influence the muscle score to a greater extent. As in other species, females showed a greater variation in weight, and carried more fat, than males during the breeding cycle. During incubation, females had greater weight and fat score than males. The weight remained constant and lean weight declined in both sexes, whereas females increased in muscle, which probably reflects the regression of the reproductive organs. During the nestling stage, both sexes declined significantly in all four indices of condition, showing evidence of physiological stress. However, the greater decline in weight in females than in males is consistent with the flight-adaptation hypothesis, as are the cyclic changes in lean weight associated with the various nesting attempts. The fact that both sexes declined significantly in weight, muscle and lean weight with an increasing number of nesting attempts, but not in fat, which was recovered after each nestling period, also indicates that both reproductive stress and adaptive changes occur during breeding. When the whole breeding season was considered, females showed a greater decline in muscle than males, which we interpret to be evidence for a greater reproductive stress in females. We suggest that the small breast muscle size and depleted protein reserves at the end of the breeding period might influence future survival through impaired flight ability and a compromised post-breeding moult.     

Early life events carry over to influence pre-migratory condition in a free-living songbird

Conditions experienced during development can have long-term consequences for individual success. In migratory songbirds, the proximate mechanisms linking early life events and survival are not well understood because tracking individuals across stages of the annual cycle can be extremely challenging. In this paper, we first use a 13 year dataset to demonstrate a positive relationship between 1(st) year survival and nestling mass in migratory Savannah sparrows (Passerculus sandwichensis). We also use a brood manipulation experiment to show that nestlings from smaller broods have higher mass in the nest relative to individuals from larger broods. Having established these relationships, we then use three years of field data involving multiple captures of individuals throughout the pre-migratory period and a multi-level path model to examine the hypothesis that conditions during development limit survival during migration by affecting an individual's ability to accumulate sufficient lean tissue and fat mass prior to migration. We found a positive relationship between fat mass during the pre-migratory period (Sept-Oct) and nestling mass and a negative indirect relationship between pre-migratory fat mass and fledging date. Our results provide the first evidence that conditions during development limit survival during migration through their effect on fat stores. These results are particularly important given recent evidence showing that body condition of songbirds at fledging is affected by climate change and anthropogenic changes to landscape structure.     

Noninvasive estimation of body composition in small mammals: a comparison of conductive and morphometric techniques

Body fat stores may serve as an index of condition in mammals. Thus, techniques that measure fat content accurately are important for assessing the ecological correlates of condition in mammal populations. We compared the ability of two conductive techniques, bioelectrical impedance analysis (BIA) and total body electrical conductivity (TOBEC), to predict body composition with that of morphometric methods in three small mammal species: red squirrels (n=13), snowshoe hares (n=30), and yellow-bellied marmots (n=4). Animals were livetrapped in northern Idaho; BIA (all subjects) and TOBEC (squirrels only) measurements were taken following chemical immobilization in the field, and morphometric measurements were taken postmortem. Information provided by BIA and TOBEC failed to improve upon the predictive power of morphometric equations for total body water (TBW) and lean body mass (LBM) in squirrels and hares, which do not store substantial amounts of fat (<5% body mass comprised of fat). Although the same pattern held with respect to LBM in marmots, which accumulate substantial amounts of body fat (>10% body mass), a BIA-based model proved best at estimating TBW, suggesting that the usefulness of conductive techniques may be a function of fat deposition. However, regardless of the technique used to predict body composition, estimates of body fat furnished by our equations failed to approximate actual fat levels accurately in all three test species, probably because these techniques only provide indirect estimates of fat content. These results highlight the limitations inherent in contemporary methods of animal fat estimation and underscore the need for the development of direct and accurate measures of body fat in mammals.     

Which body condition index is best?

Body condition indices are widely used by ecologists, but many indices are used without empirical validation. To test the validity of a variety of indices, we compared how well a broad range of body condition indices predicted body fat mass, percent body fat and residual fat mass in mice Mus musculus. We also compared the performance of these condition indices with the multiple regression of several morphometric variables on body fat mass, percent body fat and residual fat mass. In our study population, two ratio based condition indices – body mass/body length and log body mass/log body length – predicted body fat mass as well as or better than other ratio and residual indices of condition in females. In males one ratio based condition index (log body mass/log body length) and one residual index (residuals from a regression of pelvic circumference on body length) were best at predicting body fat mass. All indices were better at estimating body fat mass, and residual fat mass than at estimating percent body fat. The predictions of body fat were much better for females than for males. Multiple regressions incorporating pelvic circumference (i.e. girth at the iliac crests) were the best predictors of body fat mass, residual fat mass, and percent body fat, and these multiple regressions were better than any of the condition indices. We recommend 1) that condition be precisely defined, 2) that predictors of condition be empirically validated, 3) that pelvic circumference be considered as a potential predictor of fat content, and 4) that, in general, multiple regression be considered as an alternative to condition indices.     

Body condition of shorebirds upon arrival at their Siberian breeding grounds

Arctic breeding shorebirds carry substantial body stores on their long-distance migrations from their non-breeding grounds. Upon arrival at the breeding area the remains of these stores can be used for egg formation, insurance against poor feeding conditions or rebuilding organs. We quantified body condition (body mass, total body water, lean body mass and fat mass estimated using the deuterium dilution method) in seven shorebird species caught upon arrival in the Siberian Arctic. Arrival condition was compared with incubation condition in a subset of species. After correction for structural size, body mass was significantly lower at arrival than during incubation in most of the species (but 3–18% above lean mass). Fat index (fat mass/lean mass) varied between 5.1 and 13.2%. Fat stores were estimated to enable survival for 0.6 days for the smallest and 2.5 days for the largest species. We discuss possible functions of arrival stores: insurance, egg-formation or rebuilding organs. G. H. Visser: Deceased.     

Body composition in baboons: Evaluating a morphometric method

The objective of this study was to determine whether noninvasive morphometric measurements of olive baboons (Papio cynocephalus anubis) can reliably predict lean body mass and fat mass in this species. Crown-rump length, triceps circumference, and skinfold measures at the neck, subscapular, suprailiac, and triceps sites were obtained prior to necropsy from 21 clinically normal infant baboons at 18 weeks of age and from 22 clinically normal adolescent baboons at 5 years of age. At necropsy, the lean body mass and body fat mass were measured using gravimetric methods. Pearson's correlations and regression analysis were used to test the relationship between direct measures of lean and fat mass obtained at necropsy with calculated estimates based on morphometric measures obtained prior to death. Our null hypothesis was that the morphometric measures (individually or in combination) were not related to direct measures of fat mass or lean mass. Non-linear and multiple regression estimators, by age and gender, were derived and provided increased predictability. Our results indicate that (1) morphometric measures can accurately predict lean body mass in male and female baboons; (2) morphometric measures used to predict lean body mass change with age; (3) morphometric measures are strongly associated with body fat mass at 18 weeks of age but are not as strongly associated with body fat mass in 5-year-old baboons; (4) triceps circumference provides the best single indicator of lean body mass for both genders and age periods; (5) baboons are like humans in that adolescent females tend to accumulate body fat while males of the same age tend to develop lean mass; and (6) combinations of these morphometric measurements explain between 70% and 100% of the variability and can be used to estimate lean and fat mass in baboons.     

Validation of a quantitative magnetic resonance method for measuring human body composition

Objective: To evaluate a novel quantitative magnetic resonance (QMR) methodology (EchoMRI‐AH, Echo Medical Systems) for measurement of whole‐body fat and lean mass in humans. Methods and Procedures: We have studied (i) the in vitro accuracy and precision by measuring 18 kg Canola oil with and without 9 kg water (ii) the accuracy and precision of measures of simulated fat mass changes in human subjects (n = 10) and (iii) QMR fat and lean mass measurements compared to those obtained using the established 4‐compartment (4‐C) model method (n = 30). Results: (i) QMR represented 18 kg of oil at 40°C as 17.1 kg fat and 1 kg lean while at 30°C 15.8 kg fat and 4.7 kg lean were reported. The s.d. of repeated estimates was 0.13 kg for fat and 0.23 kg for lean mass. Adding 9 kg of water reduced the fat estimates, increased misrepresentation of fat as lean, and degraded the precision. (ii) the simulated change in the fat mass of human volunteers was accurately represented, independently of added water. (iii) compared to the 4‐C model, QMR underestimated fat and over‐estimated lean mass. The extent of difference increased with body mass. The s.d. of repeated measurements increased with adiposity, from 0.25 kg (fat) and 0.51 kg (lean) with BMI <25 kg/m² to 0.43 kg and 0.81 kg respectively with BMI >30 kg/m². Discussion: EchoMRI‐AH prototype showed shortcomings in absolute accuracy and specificity of fat mass measures, but detected simulated body composition change accurately and with precision roughly three times better than current best measures. This methodology should reduce the study duration and cohort number needed to evaluate anti‐obesity interventions.     

城市汉族的瘦体质量和脂肪质量

2009-2013年测量了城市汉族成人10451例(男性5048例,女性5403例)的16项指标值,研究了不同纬度地区汉族城市成人的瘦体质量、脂肪质量值的变化规律。研究发现:1)31个族群脂肪质量、瘦体质量均数彼此相差较大,脂肪质量最大值男性、女性均为保定汉族;最小值男性为宜春汉族、女性为宁乡汉族。瘦体质量最大值男性为呼兰汉族、女性为南阳汉族;最小值男性为赣州汉族,女性为琼海汉族。2)各族群女性脂肪质量值均大于男性,而瘦体质量值均小于男性。3)胸部、臀部(女性还有腹部)围度的发育以及全身的皮下脂肪发育水平影响着城市汉族脂肪质量的发育水平,躯干与下肢围度(男性还有上肢骨骼)发育情况影响着城市汉族人的瘦体质量发育水平。4)随纬度的增加,即从中国的南方到北方,城市汉族人的体质量、脂肪质量、瘦体质量均呈线性增大。脂肪质量、瘦体质量随纬度增加而增大共同引起了体质量规律性的变化。