Developmental patterns and body fat content of juvenile common hamsters (Cricetus cricetus l.)

In European ground squirrels Spermophilus citellus as in many ground squirrel species, late born litters are composed of fewer young than early born litters. Two alternative though not mutually exclusive hypotheses may explain this seasonal pattern of change in litter size. On the one hand, the production of few large young late in the season may be an adaptation to time limitations on the offspring, that have to complete growth and fattening prior to hibernation. Then one would expect a trade‐off between offspring number and size as the breeding season progresses. At its extreme, this hypothesis would predict that total maternal effort should be equal independent of litter size. Alternatively, litter size may be determined by physiological limitations on the mother, in that highly constrained mothers breed later and produce smaller litters. Then one would expect reduced overall maternal effort in highly constrained mothers of smaller litters. In this case, a trade‐off between litter size and offspring size would not be expected. We found that total maternal effort in terms of gestation length and the duration of lactation increased with increasing litter size, thus supporting the second hypothesis. Lactation was not terminated at natal emergence. It extended a relatively long period of time beyond the time of first litter emergence depending on litter size. During prolonged lactation, individual young of large litters made up body mass to young of small litters. As a consequence, juvenile weaning body mass was unaffected by litter size although offspring body mass at natal emergence was inversely related to litter size. This additional weight gain in young of large litters compensated for initial survival disadvantages and presumably affected fecundity at yearling age.

The onset and progression through the various stages of puberty are influenced by a number of factors (Fig. 2). In both animals and humans, the age of puberty appears to be related more to body weight than to chronologic age. Undernutrition and low body fat, or an altered ratio of lean mass to body fat, seem to delay the adolescent spurt and to retard the onset of menarche. According to Frisch, a minimum level of fatness (17% of body weight) is associated with menarche; however, a heavier minimum weight for height, representing an increased amount of body fat (22%), appears necessary for the onset and maintenance of regular menstrual cycles in girls over 16 years of age. This critical amount of body fat implies that a particular body composition, in addition to other environmental and psychosocial factors, is important in triggering and maintaining the pubertal process.

Common hamsters (Cricetus cricetus) are hibernators that rely both on body fat reserves and food stores for the winter period. They face an ongoing population decline in most parts of their distribution and recently were classified as critically endangered. Knowledge on individual body fat proportions in this species is of particular interest for conservation, because it could contribute to better understand the high plasticity in overwintering strategies, overwinter mortality rates, individual variations in reproductive output, and give information on the animals’ health state. To calculate body fat proportions, we validated a method that can be applied in the field without the use of anesthesia. To develop this method, we first analyzed the body fat in carcasses of common hamsters using Soxhlet extractions and measured four morphometric parameters (body mass, head length, tibia length, foot length). The morphometric measurements were then integrated in a linear regression model to predict body fat proportions based on the measured values. The morphometric variables yielded an explained variance (adjusted R2) of 96.42% and body fat proportions were predicted with a mean absolute error of 1.27 ± 0.11% from measured values. We applied the model to predict body fat for available field data, which consistently produced reliable values. By measuring the four morphometric parameters and following the provided instructions, body fat proportions can be reliably and noninvasively estimated in captive or free-ranging common hamsters. Furthermore, the method could be applicable to other rodents after species-specific validation.

In this study, we investigated foraging behaviour, body fat and hibernation patterns in adult common hamsters (Cricetus cricetus). In addition, we compared the proportion of body fat prior to hibernation between adult and juvenile individuals. We investigated a population of free-ranging common hamsters in an urban area in southern Vienna, Austria. We applied capture-mark-recapture techniques and focal-animal-sampling for behavioural recordings. Body fat was calculated by integrating morphometric parameters. Body temperature changes were recorded during winter using subcutaneously implanted data loggers. We calculated the time individuals spent in torpor, the number and length of torpor bouts. The results revealed sex differences in foraging behaviour, in that males were feeding mainly above ground, whereas females almost exclusively cached food. These potential differences in energy allocation prior to winter were reflected in body fat at the end of the active season. Adult males had a higher proportion of body fat than females. Although juveniles had lower body fat than adults, similar sex differences were found. During winter adult males spent more time in torpor than females, indicating differing overwintering strategies depending on the individual potential to allocate internal or external energy reserves.

Non-invasive methods for estimating body composition to monitor nutritional status in goats have been less studied. Therefore, this study estimated the body composition and fat depots of pregnant goats by using indirect measurements, such as bodyweight (BW) and ultrasound measurements of the Longissimus muscle area (LMA) and kidney fat thickness (KFT). Forty-three pregnant goats were slaughtered at 50, 80, 110 and 140 days of gestation to determine the gross energy and fat content in the body, as well as to obtain the mass of renal fat, omental fat and non-carcass fat. After the slaughter, the mass of fat depots was recorded and the whole body of the each animal was ground to take samples for determining gross energy (using a bomb calorimeter) and fat (Soxhlet extraction with ether). Animals were weighed, and ultrasonographic measurements were taken at the time of slaughter. The LMA and KFT measurements were taken between the 12th and 13th rib and after the 13th rib space, respectively, and these measurements were used to estimate total gross energy, body fat content and the renal fat, omental fat and non-carcass fat mass. Multiple regressions were performed using Proc mixed of SAS. No significant correlation was observed between gross energy and body fat composition, the number of fetuses or the days of gestation. LMA and BW were positively related to body fat and gross energy contents. KFT and BW showed a positive correlation with renal fat depots, omental fat content and non-carcass fat mass. The estimated models revealed that the total body fat increased from 15.6% to 20.8% of bodyweight from 50 to 140 days of gestation. This report is the first study using kidney fat thickness as a tool to predict fat depots in goats. LMA, BW and KFT measurements will enable the development of models to aid in the monitoring of the nutritional status of goats during pregnancy.

To examine the effects of short-term repeated weight cycling (WC) above and below the baseline (BL) body weight (BW) on body weight regulation, feeding efficiency, and fat content in old female Wistar rats when dietary fat content was kept constant. Completely randomized. Female Wistar rats, 11 months old at the beginning of the study, were randomly divided into six groups (12 per group) after a group of rats (BL) was sacrificed for baseline data collection: the high fat gain (HFG) group gained weight to 20% above the BL weight with a high fat diet (HF) and returned to BL level by food restriction (50% of ad-libitum amount) for five cycles; the high fat loss (HFL) group lost weight to 20% below the BL weight by food restriction (50% of ad-libitum amount) and regained to BL level by ad-libitum feeding for four cycles; the high fat ad-libitum (HFA) and low fat ad-libitum (LFA) groups were fed HF and low fat (LF) diet, respectively, ad-libitum for the entire study; the high fat restricted (HFR group) and low fat restricted rats (LFR group) were fed the HF and LF diet, respectively, in restricted amounts to maintain BW at BL level. A trend of increased rates of weight gain and feeding efficiencies from the first to last cycles for both WC groups was observed, and significant increases was observed between cycles 4 and 5. The rate of weight gain and feeding efficiency of HFL was significantly higher than that of the HFG group for all cycles (P<0. 05). The rates of weight loss were significantly decreasing with each successive cycle for HFG, but were unchanged for HFL. Percentage of body fat was not modified permanently from BL to sacrifice for both HFG and HFL groups. The body fat of HFA was higher than that of the other groups (P<0.01), while the body fat of LFA was significantly higher than that of the LFR, BL and HFL groups (P<0.01), but was similar to that of the HFG and HFR groups. The body fat of WC groups and HFR were similar to each other. The percentage of internal fat (retroperitoneal+omental) were similar for the WC groups. The percentage of internal fat of the HFG, HFR and LFA groups were similar, but were significantly higher than that of the BL and LFR groups (P<0.05). The percentage of internal fat of HFA was significantly higher than that of the rest of the groups (P<0.01). Short-term WC did not affect body fat content in these animals, but since weight gain became easier and weight loss became more difficult for animals in the HFG group, repeated WC may promote obesity in these rats.

The enigma of increasing serum leptin levels during peritoneal dialysis.

A Controlled Pharmacogenetic Trial of Sibutramine on Weight Loss and Body Composition in Obese or Overweight Adults

Impact of litter size, supplementary milk replacer and housing on the body composition of piglets from hyper-prolific sows at weaning

Simple SummaryAt the beginning of the productive life of rabbit does, there must be a balance between ensuring at least a minimal degree of bodily development to guarantee a successful reproductive life, and the minimization of the unproductive rearing period, but nowadays there is no clear recommendation about the optimal moment for the first artificial insemination (AI). A better body condition at the first AI (higher body protein, fat and energy), that indicates a higher degree of maturity of the rabbit doe, did not influence fertility at the first AI (that is usually very high), but improved it at the second AI (that is usually lower than the first one). The percentage of kits born alive at the first and at the second AI also were positively influenced by the body protein content at the first AI. We can conclude that the degree of maturity at the first AI is a key point to optimize the does reproductive success, with body fat and body protein content being relevant factors.The relationship among live weight, chemical body composition and energy content (at artificial insemination (AI) and three days before parturition), estimated by bioelectrical impedance with fertility rates and the percentage of kits born alive, was studied during the first three AI. The first AI was conducted at 16 weeks of age in 137 rabbit does that weighted 3.91 ± 0.46 kg. Their body chemical composition was 17.4 ± 0.50%, 16.1 ± 2.6%, 1067 ± 219 kJ/100 g body weight, for protein, fat and energy, respectively. An increase in body protein, fat and energy content at the first AI did not affect fertility at the first AI but improved it at the second AI (p ≤ 0.030). Moreover, an increase in body fat and energy content at the second AI improved fertility at the second AI (p ≤ 0.001). Fertility at the third AI was positively influenced by body protein at the third AI and the increase in body protein and fat between the second parturition and the third AI (p ≤ 0.030). The percentage of kits born alive at the first and at the second AI improved with the increase in body protein at the first AI (p ≤ 0.040). In conclusion, a minimal body protein and fat content is required at the first AI to optimize the reproductive performance in young does.

Recently, low carbohydrate diets have become very popular due to their numerous health benefits. Unfortunately, little is known about their chronic effects on the blood lipid profile and other cardiovascular disease risk factors in athletic populations. We compared the results of a four week, well-planned low carbohydrate diet (LCD) followed by seven days of carbohydrate loading (Carbo-L) on fasting lipids - triacylglycerol’s (TAG), LDL-C, HDL-C, total cholesterol (TCh), glucose, insulin and HOMA-IR levels in 11 competitive basketball players. During the experiment, we also measured body mass (BM) and body composition changes: body fat (BF), % of body fat (PBF), and fat free mass (FFM). Both diet procedures significantly changed the fasting serum concentration of TAG (p < 0.05) and body fat content (kg and %) (p < 0.05), without negative changes in FFM. The Carbo-L procedure increased (p < 0.05) fasting glucose levels significantly. A LCD may be suggested for athletes who want to reduce body mass and fat content without compromising muscle mass. Several weeks on a LCD does not change the lipoprotein - LDL-C and HDL-C level significantly, while a seven-day Carb-L procedure may increase body fat content and fasting glucose concentration. Such dietary procedures are recommended for team sport athletes to reduce fat mass, lipid profile disorders and insulin resistance.

Our objective was to determine sensitivity of myostatin null (MN) mice to obesity induction by dietary or genetic means. To induce dietary obesity, 3-week-old wild type (WT) and MN mice were fed diets with 60% calories (HF) or 10% calories from fat (LF) for 4 weeks. MN mice did gain body fat on the HF diet but to a lesser extent than WT mice. Body weight and fat content was similar in MN mice fed HF and LF diets. To induce genetic obesity, the MN mutation was incorporated into leptin db/db (DB) mice generating mice homozygous for each mutation (MNDB). Nine-week-old MNDB mice were obese, similar to DB mice. Body weight, body fat content, fat pad weight and adipocyte size were all increased in MNDB mice compared to MN and WT mice and were quite similar to DB mice. However, fasting blood glucose, an indicator of insulin resistance and diabetes, was reduced in MNDB mice compared to DB mice. These results indicate that MN mice gain less body fat than WT on a HF diet, but the MN mutation does not alter fat accumulation caused by DB mutation. Thus, MN mice are not always resistant to obesity development.

Brown adipose tissue (BAT) can be identified by (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) combined with X-ray computed tomography (CT) in adult humans. The objective of this study was to clarify the relationship between BAT and adiposity in healthy adult humans, particularly to test the idea that decreased BAT activity may be associated with body fat accumulation with age. One hundred and sixty-two healthy volunteers aged 20-73 years (103 males and 59 females) underwent FDG-PET/CT after 2-h cold exposure at 19 °C with light clothing. Cold-activated BAT was detected in 41% of the subjects (BAT-positive). Compared with the BAT-negative group, the BAT-positive group was younger (P < 0.01) and showed a lower BMI (P < 0.01), body fat content (P < 0.01), and abdominal fat (P < 0.01). The incidence of cold-activated BAT decreased with age (P < 0.01), being more than 50% in the twenties, but less than 10% in the fifties and sixties. The adiposity-related parameters showed some sex differences, but increased with age in the BAT-negative group (P < 0.01), while they remained unchanged from the twenties to forties in the BAT-positive group, in both sexes. These results suggest that decreased BAT activity may be associated with accumulation of body fat with age.

We compared the proportion of body fat in mice as measured by chemical analysis with that estimated from the proportion of body water. First, we measured the proportion of fat by chemical analysis in 78 mice that had a proportion of body fat in the range from approximately 5 to 20%. Then, we constructed a regression line that described the relationship between the proportion of body water and the proportion of body fat by using data from several other published studies in mice (% body fat = -1.20 x % body water + 88.07, r = 0.9597, sy.x = 2.75, p < 0.001). With this regression line, we estimated the proportion of body fat from the proportion of body water that was measured by drying the carcasses at 60 degrees C for 3 days. Body fat data obtained from this regression line were similar to those obtained by chemical analysis. Thus, these results suggest that reliable values for the proportion of body fat can be derived from the proportion of body water and this method provides a tool to rapidly measure the proportion of body fat in mice.

Angiotensin converting enzyme inhibition from birth reduces body weight and body fat in Sprague–Dawley rats