Mass transfer from mothers to pups and mass recovery by mothers during the post-breeding foraging period in southern elephant seals (Mirounga leonina) at King George Island

Mass transfer from mother to pup during the lactation period, and mass recovery for the same females during the foraging period were measured in the southern elephant seal at King George Island, Antarctica. During the 19.2 ± 0.9-day lactation period measured (which represented 87% of the entire nursing), females lost a mean mass of 10.56 ± 1.76 kg/day (n = 27), while their pups gained a mean mass of 5.27 ± 1.1 kg/day. There was a correlation between daily body weight gain in pups and daily weight loss by their mothers. Pup weaning mass was positively related to maternal post-partum mass. Serial samples showed that weight losses by females and gains by their pups were not linear over lactation, but showed lower values at the beginning and at the end of lactation. During the 60.5 ± 6.2-day foraging phase between the end of lactation and molt, females gained 2.21 ± 0.65 kg/day (n = 12), or 54% of the mass lost during nursing. Growth rates reported here are higher than those reported in other breeding sites. However, the ratio of body mass loss by females to gain by their pups was similar, suggesting that higher growth rates and greater weaning mass at South Shetland are due to a higher mean weight of females on arrival at this breeding site. The foraging period was shorter and the mass gained greater than those measured at South Georgia; this could be related to relatively shorter distances to foraging areas. Received: 20 September 1996 / Accepted: 28 April 1997     

Energetics of lactation in harp seals (Phoca groenlandica) from the gulf of St. Lawrence,Canada

 This study reports the findings of an integrated, comprehensive analysis of lactation energetics in harp seals conducted using longitudinal measurements of mass, body composition and milk composition from mother-pup pairs in conjunction with water flux measurements in pups. The nursing period of harp seals is a short, intense and relatively efficient period of energy transfer from mothers to pups. The average daily milk intake for pups was 3.65±0.24 kg which is equivalent to 79.5 MJ of energy. Eighty-one per cent of the energy received in the milk was metabolisable and 66% of the energy was stored by the pups as body tissue. The field metabolic rate of pups was 3.9±0.4 time basal metabolic rate. The pups were growing at a rate of 2.2 kg per day during the nursing period. The distribution of this mass gain varied in terms of tissue composition, depending on the age of the pups, but over the whole nursing period approximately half of the tissue was stored as fat. Harp seal mothers lost an average of 3.1 kg per day during lactation which was composed of 37% water, 50% fat, 11% protein and 2% ash. Mothers spent half of their time during the lactation period actively diving and only one-third of their time on the surface of the ice. Milk compositional changes followed the normal phocid pattern with increasing fat content and decreasing water content as lactation progressed. The mean mass transfer efficiency was 73%. However, this value cannot be used without qualification because female harp seals in this study fed to varying degrees, consuming an estimated 0–4.8 kg of fish per day. Feeding does not appear to be required in order to achieve the energy requirements for lactation, given the energy stores possessed by females, and some females do fast through the entire period so feeding may be considered opportunistic in nature. Accepted: 25 April 1996     

Energetics during nursing and early postweaning fasting in hooded seal (Cystophora cristata ) pups from the Gulf of St Lawrence, Canada

In this study we measured growth and milk intake and calculated energy intake and its allocation into metabolism and stored tissue for hooded seal (Cystophora cristata) pups. In addition, we measured mass loss, change in body composition and metabolic rate during the first days of the postweaning fast. The mean body mass of the hooded seal pups (n = 5) at the start of the experiments, when they were new-born, was 24.3 ± 1.3 kg (SD). They gained an average of 5.9 ± 1.1. kg · day⁻¹ of which 19% was water, 76% fat and 5% protein. This corresponds to an average daily energy deposition of 179.8 ± 16.0 MJ. The pups were weaned at an average body mass of 42.5 ± 1.0 kg 3.1 days after the experiment was initiated. During the first days of the postweaning fast the pups lost an average of 1.3 ± 0.5␣kg of body mass daily, of which 56% was water, 16% fat and 28% protein. During the nursing period the average daily water influx for the pups was 124.6 ± 25.8 ml · kg⁻¹. The average CO₂ production during this period was 1.10 ± 0.20 ml · g⁻¹ · h⁻¹, which corresponds to a field metabolic rate of 714 ± 130 kJ ·  kg⁻¹ · day⁻¹, or 5.8 ± 1.1 times the predicted basal metabolic rate according to Kleiber (1975). During the postweaning fast the average daily water influx was reduced to 16.1 ± 6.6 ml · kg⁻¹. The average CO₂ production in␣this period was 0.58 ± 0.17 ml · g⁻¹ · h⁻¹ which corresponds to a field metabolic rate of 375 ± 108 kJ · kg⁻¹ · day⁻¹ or 3.2 ± 0.9 times the predicted basal metabolic rate. Average values for milk composition were 33.5% water, 58.6% fat and 6.2% protein. The pups drank an average of 10.4 ± 1.8␣kg of milk daily, which represents an energy intake of 248.9 ± 39.1 MJ · day⁻¹. The pups were able to store 73.2 ± 7.7% of this energy as body tissue. Accepted: 15 August 1996     

Milk intake,growth and energy consumption in pups of ice-breeding grey seals (Halichoerus grypus) from the Gulf of St. Lawrence,Canada

In this study we document growth, milk intake and energy consumption in nursing pups of icebreeding grey seals (Halichoerus grypus). Change in body composition of the pups, change in milk composition as lactation progresses, and mass transfer efficiency between nursing mothers and pups are also measured. Mass transfer efficiency between mother-pup pairs (n=8) was 42.5±8.4%. Pups were gaining a daily average of 2.0±0.7 kg (n=12), of which 75% was fat, 3% protein and 22% water. The total water influx was measured to be 43.23±8.07 ml·kg^-1·day^-1. Average CO₂ production was 0.85±0.20 ml·g^-1·h^-1, which corresponds to a field metabolic rate of 0.55±0.13 MJ·kg^-1·day^-1, or 4.5±0.9 times the predicted basal metabolic rate based on body size (Kleiber 1975). Water and fat content in the milk changed dramatically as lacation progressed. At day 2 of nursing, fat and water content were 39.5±1.9% and 47.3±1.5%, respectively, while the corresponding figures for day 15 were 59.6±3.6% fat and 28.4±2.6% water. Protein content of the milk remained relatively stable during the lactation period with a value of 11.0±0.8% at day 2 and 10.4±0.3% at day 15. Pups drank an average of 3.5±0.9 kg of milk daily, corresponding to a milk intake of 1.75 kg per kg body mass gained. The average daily energy intake of pups was 82.58±19.80 MJ, while the energy built up daily in the tissue averaged 61.72±22.22 MJ. Thus, pups assimilated 74.7% of the energy they received via milk into body tissue. The lactation energetics of ice-breeding grey seals is very similar to that of their land-breeding counterparts.Abbreviations bm body mass - BMR basal metabolic rate - FMR field metabolic rate - IU international unit - RQ respiration quotient - HTO tritiated water - HT¹⁸O doubly labeled water - TBW total body water - VHF very high frequency     

Energy intake and utilisation by nursing bearded seal (Erignathus barbatus) pups from Svalbard,Norway

In this study we measure energy intake via milk in nursing bearded seal (Erignathus barbatus) pups and determine how this energy is allocated into metabolism and storage of new tissues. This was accomplished using longitudinal mass gain records and the doubly labelled water technique on nursing pups in combination with cross-sectional data on changes in milk composition from bearded seal mothers. The pups (n=3) were all less than a week old at the start of the experiments. Pups gained 3.3±0.4 kg·day^-1 of which 50% was fat, 14% protein and 36% water. Average daily water influx for the pups was 69.5±9.0 ml · kg^-1· day^-1. Average CO₂ production during the study period was 0.99±0.10 ml·g^-1·h^-1, which corresponds to a field metabolic rate of 642±67 kJ·kg^-1· day^-1, or 6.0±0.5 times the predicted basal metabolic rate according to Kleiber (1975). The pups drank an average of 7.6±0.5 kg of milk daily. This corresponds to a daily energy intake of 154±8 MJ, 47±14% of which was stored as new body tissue. Despite this high energy intake bearded seal pups do not get as fat as do other nursing phocids. This is in part due to their larger body size but also due to their very active aquatic lifestyle and the lower and more consistent fat content of the milk compared to other phocid species. Bearded seal mothers forage during lactation and may also be involved in teaching their pups to feed independently. All these data suggest that the lactation strategy of bearded seals differs from the phocid norm.     

Milk composition and lactational output in the greater spear-nosed bat, Phyllostomus hastatus

Growth rates of mammalian young are closely linked to the ability of the mother to provide nutrients; thus, milk composition and yield provide a direct measure of maternal investment during lactation in many mammals. We studied changes in milk composition and output throughout lactation in a free-ranging population of the omnivorous bat, Phyllostomus hastatus. Fat and dry matter of milk increased from 9 to 21% and from 21 to 35% of wet mass, respectively, throughout lactation. Energy increased from 6 to 9 kJ · g⁻¹ wet mass, primarily due to the increase in fat concentration. Total sugar levels decreased slightly but non-significantly. Mean sugar level was 4.0% of wet mass. Protein concentration increased from 6 to 11% of wet mass at peak lactation and then decreased as pups approached weaning age. Total milk energy output until pups began to forage was 3609 kJ. Milk levels of Mg, Fe, Ca, K, and Na averaged 0.55 ± 0.26, 0.23 ± 0.2, 8.75 ± 4.17, 5.42 ± 2.11, and 9.87 ± 4.3 mg · g⁻¹ dry matter, respectively. Of the minerals studied, calcium appears to be most limiting in this species. The high degree of variability in foraging time, milk composition and milk yield between individuals at the same stage of lactation could potentially yield high variance in reproductive success among females of this polygynous species. Accepted: 23 January 1997     

Mass changes during their annual cycle in females of southern elephant seals at King George Island

Mass changes in female southern elephant seals, sampled sequentially at different points through their annual cycle, were measured at King George Island, South Shetland Islands, during the 1995/1996 and 1996/1997 field seasons. Females weighed after they had given birth showed an increase of 37 ± 36 kg (mean ± SD), which represented 6.2 ± 6.4% in relation to their mass in the first breeding season. During the first aquatic phase, between the end of lactation and the beginning of moult, females gained a mean of 128 ± 35 kg, (n = 18) (2.19 ± 0.65 kg day⁻¹), which represented between 27 and 83% of the mass they had lost during lactation. Nine females followed during moulting showed a mass loss rate of 5.0 ± 0.4 kg day⁻¹, which was half the rate during lactation. Total mass loss during moulting (129 ± 22 kg) was not significantly different from mass gain for the same females between lactation and moult (135 ± 37 kg). Furthermore, at the end of moulting, female mass was not significantly different from the mass at the end of lactation. These masses represented 65 ± 5% and 64 ± 5%, respectively, of their initial mass after parturition. During the second period at sea, from the end of the moult until females hauled out to give birth in the following breeding season, the estimated mass gain was 1.45 ± 0.24 kg day⁻¹ (n = 5), which was not significantly different to the rate of mass gain shown by the same females during the first period at sea (2.26 ± 0.70 kg day⁻¹). Total mass gain during the second aquatic phase (364 ± 63 kg) was not correlated with the mass at the end of moulting, but it was positively related to the mass loss experienced by females from parturition until the end of the moulting period in the first breeding season. Accepted: 5 September 1998     

Effects of deoxynivalenol (DON) in the lactation diet on the feed intake and fertility of sows

A diet contaminated with 2.8 mg deoxynivalenol (DON)/kg was fed at 6 kg per day to 32 mycotoxin-exposed pluriparous sows (M) during lactation. The 31 control sows (C) received 6 kg of an uncontaminated diet. Although more contaminated diet was refused (P = 0.05), DON exposure had no effect (P > 0.1) on body weight loss of the sows during lactation (M: 27.9 ± 12.3 kg; C: 29.7 ± 10.2 kg), the number of weaned piglets (M: 9.8 ± 1.4; C: 9.7 ± 1.6) and their daily weight gain (M: 266 ± 70 g; C: 272 ± 64 g). Several sows were culled after weaning for reasons unrelated to the experiment. Compared with the remaining 21 C sows, the remaining 26 M sows had an identical interval between weaning and the next farrowing (M: 120 ± 1 days; C: 120 ± 1 days) and a similar litter size (M: 14.5 ± 2.7; C: 14.9 ± 3.0; P > 0.10). The daily intake of 17 mg DON during lactation thus did not affect the reproductive performance of the sows.     

Postweaning duration and body composition changes in Southern elephant seal (Mirounga leonina) pups at King George Island.

Weaning mass in southern elephant seals is highly variable, the heaviest pups being three times as heavy as the lightest ones. After weaning, pups undergo an extensive postweaning period in which they draw on their reserves. To quantify the energy expenditure during the postweaning period, changes in mass, body composition, and postweaning duration were measured in southern elephant seals at King George Island, South Shetland Islands, Antarctica. Overall, mean pup weaning mass was 154 +/- 26 kg (n=117) and did not differ between sexes. Mean minimum postweaning duration was 42.5 +/- 7.5 d. Heavier animals at weaning had lower mass-specific mass loss rates than lighter ones, and a faster depletion of body reserves was associated with a shorter postweaning period. The proportion of body mass represented by fat at weaning was 37% +/- 4% (n=47) and did not differ between sexes. Of these pups, 36 were recaptured after a mean period of 36 d after weaning. On average, total mass loss measured in these animals (39 kg) was composed of 39% water, 47% fat, and 12% protein. The composition of mass loss was not significantly different between sexes and was not related to weaning mass or total body energy reserves. However, fatter animals at weaning lost more fat per kilogram lost than thinner ones. Late in the fast, males and females appeared to be in a similar body condition. Nevertheless, the overall proportion of body mass represented by fat at this time was lower than that presented by the same animals at weaning. We estimated that during the postweaning period pups lost, on average, 30% of their mass at weaning. This comprised approximately 35% of the energy and 32% of the fat in the pup's body.     

Food consumption estimates of southern elephant seal females during their post-breeding aquatic phase at King George Island

Changes in mass and body composition, measured with labelled water, were used to quantify the energy expenditure during lactation and energy replenishment during the post-breeding aquatic phase in Southern elephant seal females at Stranger Point, King George Island. During lactation females spent a mean of 6,021±1,365 MJ, which resulted in a loss of 35% of the initial mass, comprising 63% of initial body fat and 20% of initial body protein. During the 58±5.4 day post-breeding foraging period, females gained 135±39 Kg, which allowed them to recover an average of 55% of the mass, including 46% of the fat, 71% of the protein and 47% of the energy lost during lactation. Neither the mass nor the energy lost during lactation were related to those replenished while at sea. However, protein loss expressed in absolute terms or as a proportion of that present at the beginning of lactation explained about 50% of the variation in the protein gained during the post-breeding phase. This might indicate the presence of a mechanism favouring an increase in lean tissue during post-breeding. Daily energy requirements for an average sized female, during the post-breeding aquatic phase were estimated at 96 MJ. Estimation of prey consumption varies according to assumptions about diet composition. On a basis of 450 females, the total biomass of fish and squid consumed by the breeding group, assuming a diet composed of 75% cephalopods and 25% fish, was estimated to be 521 and 174 metric tonnes, respectively, for the period examined.     

Fat transfer and energetics during lactation in the hooded seal: the roles of tissue lipoprotein lipase in milk fat secretion and pup blubber deposition

Hooded seals (Cystophora cristata) lactate for 3.6 days during which females simultaneously fast and transfer large amounts of energy to their pups through fat-rich milk. Pups grow rapidly, principally due to blubber deposition. Lipoprotein lipase (LPL), the primary enzyme responsible for tissue uptake of triglyceride fatty acids, may strongly influence both maternal milk fat secretion and pup blubber deposition. We measured the energetic costs of lactation (using hydrogen isotope dilution, ³H₂0), milk composition, prolactin, and LPL activity (post-heparin plasma LPL [PH LPL], blubber, mammary gland and milk; U) in six females. PH LPL and blubber LPL were measured in their pups. Females depleted 216.3 MJ · day⁻¹ of body energy and fat accounted for 59% of maternal mass loss and 90% of postpartum body energy loss, but maternal body composition changed little. Maternal blubber LPL was negligible (0.0–0.2 U), while mammary LPL was elevated (1.8–2.5 U) and was paralleled by changes in prolactin. Estimated total mammary LPL activity was high (up to 20,000 U · animal⁻¹) effectively favoring the mammary gland for lipid uptake. Levels of total blubber LPL in pups increased seven-fold over lactation. Pups with higher PH LPL at birth had greater relative growth rates (P = 0.025). Pups with greater blubber stores and total blubber LPL activity had elevated rates of fat deposition (P = 0.035). Accepted: 4 May 1999     

Energetics of offspring production: a comparison of a marsupial (Monodelphis domestica) and a eutherian (Mesocricetus auratus)

This study compares the energetic cost of reproduction during gestation and lactation of a eutherian, the golden hamster (Mesocricetus auratus), and a similar-sized (60–120 g) marsupial, the gray short-tailed opossum (Monodelphis domestica). Food consumption was monitored in 20 reproductively active (RA) opossums and 16 RA hamsters from conception to weaning and at equivalent intervals in 19 non-reproductive (NR) opossums and 21 NR hamsters, all maintained within their zone of thermoneutrality (30 °C). Total energy assimilated from conception to weaning [opossums: 1261.3 ± 28.0 Kcal (1 Kcal = 4.1868 J) and hamsters: 1647.5 ± 60.6 Kcal] was positively correlated with litter size and mass per young in both species. Maternal mass-specific assimilated energy was significantly greater in hamsters than in opossums during gestation (P < 0.001), but not during lactation or from conception to weaning (P > 0.05). Efficiency of offspring production (energy stored in young/incremental energy in RA females) was higher in hamsters than in opossums and, in both species, it was higher during lactation than in gestation. The energetic cost of reproduction (per young per day) was higher in hamsters than in opossums. The marsupial mode of reproduction, as seen in opossums, yields young at lower cost but requires a longer reproductive period than is the case for a similar-sized eutherian. Accepted: 8 September 1998     

Supplementing sow diets with palm oil during late gestation and lactation: effects on milk production,sow hormonal profiles and growth and development of her offspring

The supplementing of sow diets with lipids during pregnancy and lactation has been shown to reduce sow condition loss and improve piglet performance. The aim of this study was to determine the effects of supplemental palm oil (PO) on sow performance, plasma metabolites and hormones, milk profiles and pre-weaning piglet development. A commercial sow ration (C) or an experimental diet supplemented with 10% extra energy in the form of PO, were provided from day 90 of gestation until weaning (24 to 28 days postpartum) in two groups of eight multiparous sows. Gestation length of PO sows increased by 1 day (P<0.05). Maternal BW changes were similar throughout the trial, but loss of backfat during lactation was reduced in PO animals (C: −3.6±0.8 mm; PO: −0.1±0.8 mm; P<0.01). Milk fat was increased by PO supplementation (C day 3: 8.0±0.3% fat; PO day 3: 9.1±0.3% fat; C day 7: 7.8±0.5% fat; PO day 7: 9.9±0.5% fat; P<0.05) and hence milk energy yield of PO sows was also elevated (P<0.05). The proportion of saturated fatty acids was greater in colostrum from PO sows (C: 29.19±0.31 g/100 g of fat; PO: 30.77±0.36 g/100 g of fat; P<0.01). Blood samples taken on 105 days of gestation, within 24 h of farrowing, day 7 of lactation and at weaning (28±3 days post-farrowing) showed there were no differences in plasma concentrations of triacylglycerol, non-esterified fatty acids, insulin or IGF-1 throughout the trial. However, circulating plasma concentrations of both glucose and leptin were elevated during lactation in PO sows (P<0.05 and P<0.005, respectively) and thyroxine was greater at weaning in PO sows (P<0.05). Piglet weight and body composition were similar at birth, as were piglet growth rates throughout the pre-weaning period. A period of 7 days after birth, C piglets contained more body fat, as indicated by their lower fat-free mass per kg (C: 66.4±0.8 arbitrary units/kg; PO: 69.7±0.8 arbitrary unit/kg; P<0.01), but by day 14 of life this situation was reversed (C: 65.8±0.6 arbitrary units/kg; PO: 63.6±0.6 arbitrary units/kg; P<0.05). Following weaning, PO sows exhibited an increased ratio of male to female offspring at their subsequent farrowing (C: 1.0±0.3; PO: 2.2±0.2; P<0.05). We conclude that supplementation of sow diets with PO during late gestation and lactation appears to increase sow milk fat content and hence energy supply to piglets. Furthermore, elevated glucose concentrations in the sow during lactation may be suggestive of impaired glucose homoeostasis.     

Growth of the first antler in Iberian red deer (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>)

In this study, we describe the process of pedicle and first antler growth in Iberian red deer (Cervus elaphus hispanicus) and document relationships among body development, maternal milk supply and composition, and maternal weight on the length of first antlers. Antler length of 53 males of Iberian red deer was measured every 2 weeks from birth to 20 months of age. Deer weight, age, and the date of occurrence of the major events during the antler growth cycle were also recorded. The first evidence of pedicle development occurred when the animals were 38.0 ± 0.6 weeks old and weighed 60.7 ± 0.9 kg. Antler cleaning took place at a mean age of 63.8 ± 0.7 weeks and a mean weight of 91.5 ± 1.8 kg. The antler growth period lasted 16.7 ± 0.4 weeks, and the cleaning period lasted 5.1 ± 0.4 weeks. First antler growth followed a sigmoid curve, reaching a final length of 38.3 ± 1.0 cm. Antler length was positively correlated with body weight during the antler growth cycle. Additionally, the final length of the first antler was related to total milk yield, date of antler growth initiation, body weight at 6 months of age, and the antler growth time interval.     

Energy requirements and efficiency of Alpine goats in early lactation

Dairy goats may rely heavily on body fat and protein reserves in early lactation. Therefore, we aimed to determine the energy requirement and estimate the efficiency of utilization the nutrients of tissues mobilized in the first 8 weeks of lactation for milk production using the comparative slaughter technique. The average initial body mass of 51 multiparous goats was 57.19 ± 8.38 kg and a body condition score of 3.0 ± 0.5. Three goats were slaughtered at the beginning of the experiment to serve as baseline animals to estimate initial empty BW and initial body composition. We used a complete randomized design in which the factor was the day of lactation for slaughtering (the 7th, 14th, 21st, 28th, 35th, 42nd, 49th and 56th day), with six repeats, totalling 48 goats. No fasting before slaughtering. All animals received a single experimental diet. The efficiency of transferring energy from body reserves to milk was estimated using a multiple linear regression equation yielding a value of 0.76. The total energy stored in the empty body decreased over the eight lactation weeks, from 726.47 ± 26.19 to 316.18 ± 49.21 MJ, a 56.47% reduction, mainly because of a reduction in the energy from internal fat of 3.96 ± 1.98 MJ/day. In conclusion, the net energy required for maintenance is 60 ± 30 kJ/BW^0.75 per day, and the net energy required for lactation decreases 70 ± 30 kJ/day during the first eight lactation weeks.     

Lactation costs in southern elephant seals at King George Island,South Shetland Islands

Labelled-water methodology was used to quantify energy costs and energy transfer efficiency in 18 mother-pup pairs of southern elephant seals (Mirounga leonina) during lactation. During the lactation period, mothers lost a mean mass of 227±47 kg. Mass loss included 22% of the protein, 60% of the fat, and 51% of the energy in the mothers body upon arrival. Total body-energy reserves at parturition explained 69% of the variation in the total lactation costs and 50% of the variation in the pups body energy at weaning. On average, pups retained 48% of the mass, 49% of protein, 53% of fat and 51% of energy lost by their mothers. Greater, fatter females showed a decrease in the efficiency of energy and fat transfer and, at the same time, an increase in the efficiency of protein transfer. This may be due to an increased use of protein as metabolic fuel, as fat demands for milk production increase. There was no evidence that greater total lactation costs influence the ability of mothers to produce a pup in the next breeding season.     

Validation of a dual energy X-ray absorptiometer: measurement of bone mass and soft tissue composition

We investigated the reproducibility of total and regional body composition measurements performed on a dual energy X-ray absorptiometer (DXA). A group of 38 women aged 21–81 (mean 52. 4) years was scanned twice with repositioning to determine intra-observer reproducibility of measurements of bone mineral density (BMD, g · cm⁻²), bone mineral content (BMC, g), lean mass (LM, kg) and fat mass (FM, kg) of the total body and of the major subregions of the body. In addition, the ability of the DXA machine to detect changes in LM and FM (simulated by placing 11.1 and 22.3 kg porcine lard on the body of 11 subjects) was examined. Coefficients of variations calculated from the root mean square averages of individual standard deviations were as follows (BMD, BMC, FM, LM): 1.4%, 1.1%, 1.4%, 1.7% (total body), 2.2%, 2.1%,-,- (head), 2.8%, 2.8%, 2.0%, 2.2% (trunk), 3.6%, 3.9%, 4.0%, 4.9% (arms), 2.7%, 1.3%, 2.6%, 2.8% (legs). Percentage fat (%fat) of exogenous lard was 81.3 (SD 3.5)% as assessed by the absorptiometer which corresponded well with the result of chemical analysis (82.8%). Estimated %fat of exogenous lard was not influenced by initial body mass or percentage body fat. Percentages of expected mean values with 11.1 kg lard placed on the body were 99.9 (SD 0.3) for body mass, 100.5 (SD 2.1) for LM, and 99.5 (SD 3.5) for FM. BMD was overestimated by 3.2% (P < 0.005) with 11.1 kg lard on the body. BMD as well as BMC increased significantly with 22.3␣kg lard on the body (P < 0.005). The results showed that BMD, BMC, LM, and FM of the total body were precisely estimated by the DXA machine used. Regional measurements were less precise. Changes in total body soft tissue composition were precisely and accurately estimated. The lard placed on the body falsely affected BMD and BMC measurements. Changes in body mass could have a similar effect. Accepted: 6 January 1997     

Food requirements of breeding king penguins at Heard Island and potential overlap with commercial fisheries

The diet composition of king penguins (Aptenodytes patagonicus) at Heard Island (53°05′S; 73°30′E) was determined from stomach contents of 98 adults captured as they returned to the island throughout 1992. During the two growth seasons, the diet was dominated by the myctophid fish Krefftichthys anderssoni (94% by number, 48% by mass). The paralepidid fish Magnisudis prionosa contributed <1% by numbers but 17% by mass. Mackerel icefish (Champsocephalus gunnari) accounted for 17% by mass of chick diet in late winter, when chicks were malnourished and prone to starvation, although its annual contribution to the penguins' diet was only 3%. Squid was consumed only between April and August; Martialia hyadesi was the commonest squid taken, comprising 40–48% of the winter diet. The remainder of the diet consisted of the squid Moroteuthis ingens and fish other than K. anderssoni. The energy content of the diet mix fed to the chicks varied seasonally being highest during the growth seasons (7.83 ± 0.25 kJ g⁻¹) and lowest in winter (6.58 ± 0.19 kJ g⁻¹). From energetic experiments we estimated that an adult penguin consumed 300 kg of food each, of which its chick received 55 kg during the 1992 season. The chicks received large meals at the beginning of winter (1.2 ± 0.3 kg) and during the middle of the second growth season (1.2 ± 0.3 kg), and their smallest meals in late winter (0.4 ± 0.1 kg). The gross energy required to rear a king penguin chick was estimated to be 724 MJ. The potential impact of commercial fisheries on the breeding activities of king penguins is discussed. Received: 20 October 1997 / Accepted: 27 April 1998     

Plasma Zinc Concentration,Body Composition and Physical Activity in Obese Preschool Children

Zinc (Zn) deficiency and obesity can be observed together in some developing countries. Zn deficiency may enhance fat deposition and decrease lean mass accrual, which in turn, appears to influence physical activity (PA), although this has not yet been evaluated in obese children. The objective of the study was to find out the association between measurements of plasma Zn and serum leptin, body composition, and PA in Chilean obese preschool children. Seventy-two 18- to 36-month-old obese children [weight-for-length/height z score (WHZ) > 2.0 SD], belonging to low socioeconomic communities, participated in the study. Plasma Zn, serum leptin, weight, waist circumference, height, total body water (TBW) assessed by deuterium isotopic dilution technique and daily activity, measured by registering 48 h with an accelerometer, were evaluated. We found 82% of children with WHZ > 3 SD. The geometric mean Zn intake was 6.2 ± 2.5 mg/day. The mean plasma Zn was 91.8 ± 11.4 μg/dL, with 10% of the children having levels <80 μg/dL. No correlation was found between plasma Zn concentrations and either weight, WHZ, or waist circumference. Serum leptin was lower in males than in females (2.9 ± 2.8 vs 6.8 ± 5.0 ng/mL, respectively; p < 0.001). TBW was different between males and females (56.2 ± 5.4 vs 52.8 ± 4.3% body weight, respectively; p = 0.004), but no significant association was found between TBW and plasma Zn. Moderate + intense PA, (as percentage of wake time), was greater in males than in females (6.3 ± 3.1% vs 3.4 ± 2.3%, respectively; p < 0.001), but it was not significantly correlated to plasma Zn. In conclusion, plasma Zn was not associated with body composition as assessed by TBW, serum leptin, or with the magnitude of physical activity in Chilean overweight preschool children.     

Is tissue maturation necessary for flight? Changes in body composition during postnatal development in the big brown bat

Patterns of offspring development reflect the availability of energy and nutrients, limitations on an individual’s capacity to use available resources, and tradeoffs between the use of nutrients to support current metabolic demands and tissue growth. To determine if the long period of offspring dependency in bats is associated with the need for an advanced state of tissue maturation prior to flight, we examined body composition during postnatal growth in the big brown bat, Eptesicus fuscus. Despite their large size at birth (22% of maternal mass), newborn bats are relatively immature, containing 82% body water in fat-free mass. However, the total body water content of newborn bat pups decreases to near-adult levels in advance of weaning, while concentrations of total body fat and protein exceed adult values. In contrast to many other mammals, postnatal growth of bat pups was characterized by relatively stable concentrations of calcium and phosphorus, but declining concentrations of magnesium. These levels remained stable or rebounded in late postnatal development. This casts doubt on the hypothesis that low rates of mineral transfer necessitate an extended lactation period in bats. However, our finding of near-adult body composition at weaning is consistent with the hypothesis that extended lactation in bats is necessary for the young to achieve sufficient tissue maturity to undertake the active flight necessary for independent feeding. In this respect, bats differ from most other mammals but resemble birds that must engage in active flight to achieve nutritional independence.