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.     

Energy gain and loss during lactation and postweaning in southern elephant seal pups (Mirounga leonina) at King George Island

Deuterium-labeled water was used to measure changes in the proximate body composition during the lactation period and after weaning in southern elephant seal pups at King George Island, South Shetland Islands, Antarctica. During the lactation period (23.0 ± 1.4 days) pups gained a mean of 4.9 ± 0.5 kg/day (n=7). Of the total mass gain (112 ± 8 kg), 38% was water, 48% was fat, and 11% was protein. This represented an increase in total body gross energy of 2437 ± 145 MJ. The proportion of body mass represented by fat was less than 2% at birth, increasing to 35 ± 2% at weaning. We followed the pups during a mean period of 36 ± 3 days after weaning. During this period, pups had a mean loss of 1.21 ± 0.10 kg/day (n=7) comprising 39% water, 48% fat, and 12% protein. The energy cost over this period was 952 ± 168 MJ, which represented, on average, 39% of the total energy gained during the suckling period. Accepted: 3 January 2000     

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     

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     

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.     

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     

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.     

Temporal changes in body mass, body composition and metabolism of gibel carp Carassius auratus gibelio during food deprivation

To investigate the response to starvation, gibel carp Carassius auratus gibelio [12.5 ± 0.03 g (mean ± SE, n = 24)] were deprived of food at 25.8 ± 0.2°C (mean ± SE, n = 56) for 56 days. Body mass, proximate composition in whole body and muscle, and respiration were measured at 7‐day intervals. Body mass decreased with prolongation of deprivation, with a significant decline recorded after 7 days deprivation. Fish lost 22% of their fresh mass and 34% of dry mass after 56 days. Fish lost 38% of the body lipid over the first 7 days, and lost body lipid at a rate of 0–11% per week over the remaining 49 days. Body protein was lost at 1–5% per week throughout deprivation. Compared with the initial composition, body lipid concentration was lower and ash concentration higher on day 7. Water as a percentage of body mass was higher after 28 days, and protein concentration lower after 42 days, than at the start of deprivation. Muscle lipid and protein concentration was lower, and % water higher, after 7 days than at the start of deprivation, whereas muscle ash concentration was relatively constant during deprivation. After 56 days, fish lost body water by 18%, body lipid by 84%, body protein by 30%, and body energy by 45%. Oxygen consumption rate dropped from day 1 to day 3, increased from day 4 to day 14, gradually decreased from day 15 to day 35, and maintained a relatively constant level from day 36 to day 56. Results of the present experiment reveal that gibel carp utilize body lipid as a major energy source in the first 7 days of food deprivation, then turn to body protein as an energy fuel when lipid reserves are heavily depleted. Oxygen consumption is maintained at a relatively low and constant level when most lipid reserves are exhausted.     

Energy Intake and Physical Activity in Pima Indians: Comparison with Energy Expenditure Measured by Doubly-Labeled Water

To test the validity of survey techniques for measuring diet and activity patterns of Pima Indians, sequential 24-hour recalls, a food frequency ques tionnaire (FFQ), and an activity questionnaire were compared to free-living energy expenditure. Total energy expenditure (TEE) measured by doubly labeled water was 13.27 ± 2.95 MJ/d for the 12 males (mean±SD: 35 ± 14 yr; 97 ± 35 kg; 32 + 9% body fat) and 11.67 ± 1.85 MJ/d for the 9 females (31 ± 13 yr; 106 ± 32 kg; 49 ± 6% body fat). Energy intake assessed by 24-hour recall was 13.59 ± 7.81 MJ/d for men and 9.29 ± 2.77 MJ/d for women, compared to 12.84 ± 2.85 and 9.40 ± 2.61 MJ/d for men and women, respectively, by FFQ. Both dietary methods indicated significant underreporting by women when compared to TEE. Energy intake assessed by FFQ was significantly correlated with TEE (r=0.48, p=0.03). This was true with 24-hour recall energy intake only when data from two extremely large alcohol consumers were eliminated (r=0.64, p=0.03, N=19). Although a low level of activity was apparent, the activity questionnaire produced significant correlations with measurements of energy expenditure and therefore represents an important tool for examining the relationship between physical activity and diseases.     

Estimates of individual factors of the tryptophan requirement based on protein and tryptophan accretion responses to increasing tryptophan supply in broiler chickens 8-21 days of age

Ten diets (196 g CP and 13.0 MJ ME(N)/kg) with graded levels of tryptophan (Trp) between 0.9 and 2.7 g/kg were offered ad libitum to Ross broilers from day 8-21 post-hatch. Each diet was allocated to three pens of ten birds each. In addition to growth and feed conversion, the accretions of protein, Trp, fat, and energy were determined by comparative whole body analyses. A sigmoidal function was fitted to the data. Responses to Trp supply were nonlinear and attained plateau values (y(max)) within the studied range of Trp supply. The Y(max) values estimated for BW gain, whole body protein gain, and Trp gain during the 14 days under study were 615, 104, and 0.87 g/bird, respectively. Based on the response in whole body protein gain, the estimated requirement was 1.9 g Trp/kg of diet or 0.15 g Trp/MJ of MEN. Estimates made from the other response criteria were similar to this value. While the protein concentration in gained BW was unaffected by Trp intake (169 g of protein per kg of gained BW), fat and energy concentrations of gained BW increased with increasing Trp supply, approaching plateau values of 146 g fat and 9.8 MJ energy per kg of gained BW. This is supposed to result from feed intake increasing with Trp supplementation. The Trp concentration in gained whole body protein (0.84 g Trp/ 16 g of gained N) was not significantly affected by Trp intake. As long as Trp intake was the limiting factor, 59% of supplemented Trp was transferred to gained whole body protein. During the 14 days of the study, broilers inevitably lost 87 mg Trp. This is equivalent to a daily loss of 30 mg/kg BW or a maintenance requirement of 52 mg/kg BW per day. Data determined for the individual factors may be used for future modelling of broilers' Trp requirement.     

Non Linear Weight Gain with Long Term Overfeeding in Man

This study deals with the pattern of body weight gain during an overfeeding period with a constant energy intake, in order to assess whether total daily energy expenditure (TEE) increased with body weight and thus could account for the progressive slow down in body weight gain over time. Twenty-four young adult males (12 pairs of identical twins) were overfed by 4.2 MJ per day, six days a week, for a total of 84 days during a 100-day overfeeding period. The total excess amount each man consumed was 353 MJ. It was assumed that, at a given time, the TEE increase (E) was dependent on body weight gain and energy cost (C) was proportional to the daily body weight gain. Results show an exponential increase in body weight, fat free mass, and fat mass (with half-times of 86, 57, and 84 days, respectively) that allows the calculation of E (246 ± 37 kJ*kg^?1 d^?1, mean ± SE) and C (32.3 ± 2.4 MJ kg^?1). Energy expenditure from other sources besides resting metabolic rate, such as physical activity and thermic effect of food, may represent as much as 65% of E. At the beginning of the overfeeding period, almost all the energy surplus was recovered as body substances but this proportion decreased to 60% after 100 days of overfeeding. It is concluded that 1) TEE changes were related to body weight change, 2) about 65% of E were accounted for by physical activity, thermic effect of food, or some other components, and 3) the fraction of the energy surplus stored as body substances decreased with the duration of overfeeding.     

Cold exposure does not decrease serum leptin concentration,but increases energy intake and thermogenic capacity in pregnant Brandt's voles (Lasiopodomys brandtii)

In most mammals, maternal body mass and fat mass increase during pregnancy due to hyperphagia. These physiological changes provide the fetus with energy and nutrients and prepare the mother for the high energetic demands of lactation. In the present study, metabolic changes in response to cold and pregnancy were examined in female Brandt's voles (Lasiopodomys brandtii). At 23±1 °C, the voles increased body mass and deposited body fat during pregnancy. However, at 5±1 °C pregnant voles did not deposit body fat even though energy intake increased above the level in the warm. Serum leptin concentration increased during pregnancy and was not influenced by cold exposure. Thermogenic capacity, as indicated by uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT), increased in cold-exposed pregnant voles. The number and mass of fetuses were not affected by cold exposure. Our data may indicate the importance of an increased serum leptin concentration for a successful outcome of the pregnancy and also the independence of leptin secretion from body fat in pregnant voles. It also implies the need to develop central leptin resistance with respect to control of energy balance for pregnant voles.     

Estimates of individual factors of the tryptophan requirement based on protein and tryptophan accretion responses to increasing tryptophan supply in broiler chickens 8 – 21 days of age

Ten diets (196?g CP and 13.0 MJ ME_N/kg) with graded levels of tryptophan (Trp) between 0.9 and 2.7?g/kg were offered ad libitum to Ross broilers from day 8?–?21 post-hatch. Each diet was allocated to three pens of ten birds each. In addition to growth and feed conversion, the accretions of protein, Trp, fat, and energy were determined by comparative whole body analyses. A sigmoidal function was fitted to the data. Responses to Trp supply were nonlinear and attained plateau values (y_max) within the studied range of Trp supply. The y_max values estimated for BW gain, whole body protein gain, and Trp gain during the 14 days under study were 615, 104, and 0.87?g/bird, respectively. Based on the response in whole body protein gain, the estimated requirement was 1.9?g Trp/kg of diet or 0.15?g Trp/MJ of ME_N. Estimates made from the other response criteria were similar to this value. While the protein concentration in gained BW was unaffected by Trp intake (169?g of protein per kg of gained BW), fat and energy concentrations of gained BW increased with increasing Trp supply, approaching plateau values of 146?g fat and 9.8 MJ energy per kg of gained BW. This is supposed to result from feed intake increasing with Trp supplementation. The Trp concentration in gained whole body protein (0.84?g Trp/16?g of gained N) was not significantly affected by Trp intake. As long as Trp intake was the limiting factor, 59% of supplemented Trp was transferred to gained whole body protein. During the 14 days of the study, broilers inevitably lost 87?mg Trp. This is equivalent to a daily loss of 30?mg/kg BW or a maintenance requirement of 52?mg/kg BW per day. Data determined for the individual factors may be used for future modelling of broilers' Trp requirement.     

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     

Water balance and the energetics of lactation in grey seals (Halichoerus grypus) as studied by isotopically labelled water methods

The energetics of lactation in grey seal females and their pups was investigated using labelled water methods. Average total energy output (maternal maintenance energy expenditure plus milk energy output), from the estimated change in total body gross energy, of 15 females was 99.8 MJ/d (S.E. 2.5), which was nearly 30% lower than previously published estimates. In seven females, energy output was partitioned into milk energy output plus maternal maintenance energy expenditure. Average investment in milk was 69.7MJ/d (S.E. 5-0), and lactation costs accounted for 70% of total maternal energy output. Average daily maternal maintenance energy expenditure (heat output) of the same seven females was 30.0MJ/d (S.E. 5.0), which was equivalent to 2.3 times the basal metabolic rate predicted from Kleiber's (1975) allometric equation. In seven pups, milk consumption rates were measured isotopically and these averaged 3.0kg/d (S.E. 0.2). In four pups energy expenditure, measured using doubly-labelled water, averaged 13.5MJ/d (S.E. 1.2), equivalent to 3.7 times the basal metabolic rate predicted from Kleiber's (1975) equation. All females were in negative water balance during lactation which was associated with loss of tissue during fasting. Mean water efflux was 3966ml/d (S.E. 286) and mean water influx was 2677ml/d (S.E. 245), but there was no evidence that females are dehydrated during lactation.     

Efficacy of α‐Lactalbumin and Milk Protein on Weight Loss and Body Composition During Energy Restriction

Our objective was to examine whether elevated α‐lactalbumin (αlac) protein intake compared to elevated supra sustained milk protein (SSP) and sustained milk protein (SP) intake results into a difference in body weight and body composition over a 6‐month energy‐restriction intervention. Body weight, body composition, resting energy expenditure (REE), satiety and blood‐ and urine‐parameters of 87 subjects (BMI 31 ± 5 kg/m² and fat percentage 40 ± 8%) were assessed before and after daily energy intakes of 100, 33, and 67% for 1, 1, and 2 months respectively (periods 1, 2, and 3), with protein intake from meal replacements and 2 months of 67% with ad libitum protein intake additional to the meal replacements (period 4). The diets resulted in 0.8 ± 0.3 g/kg body mass (BM) for SP and significant higher protein intake (24‐h nitrogen) of 1.2 ± 0.3 and 1.0 ± 0.3 g/kgBM for SSP and αlac (P < 0.05). Body weight and fat percentage was decreased in all groups after 6 months (SP ?7 ± 5 kg and ?5 ± 3%; SSP ?6 ± 3 kg and ?5 ± 3%; αlac ?6 ± 4 kg and ?4 ± 4%, P < 0.001; there was no significant group by time difference). Furthermore, sparing of fat‐free mass (FFM) and preservation of REE in function of FFM during weight loss was not significantly different between the αlac‐group and the SSP‐ and SP‐groups. In conclusion, the efficacy of αlac in reduction of body weight and fat mass (FM), and preservation of FFM does not differ from the efficacy of similar daily intakes of milk protein during 6 months of energy restriction.     

Successful long-term weight maintenance: a 2-year follow-up

Objective: To find factors associated with successful weight maintenance (WM) in overweight and obese subjects after a very low‐calorie diet (VLCD). Research Methods and Procedures: Subjects (133) followed a VLCD (2.1 MJ/d) for 6 weeks in a free‐living situation. Of these, 103 subjects (age, 49.6 ± 9.7 years; BMI, 30.9 ± 3.8 kg/m²) completed the following 2‐year WM period. Body weight (BW), body composition, leptin concentration, attitude toward eating, and physical activity were determined right before (t0) and after (t1) the VLCD, after 3 months (t2), after 1 year (t3), after 1.5 years (t4), and after 2 years (t5). Results: BW loss during VLCD was 7.2 ± 3.1 kg. After 2 years, follow‐up BW regain was 69.0 ± 98.4%. After 2 years of WM, 13 subjects were successful (<10% BW regain), and 90 were unsuccessful (>10% BW regain). At baseline, these groups were significantly different in BMI (33.7 ± 4.7 vs. 30.5 ± 3.5 kg/m², respectively; p < 0.05) and fat mass (38.3 ± 9.8 vs. 32.1 ± 8.3 kg, p < 0.05). Successful subjects increased their dietary restraint significantly more during the whole study period (dietary restraint score, ?4.9 ± 4.4 vs. ?2.1 ± 3.8). Furthermore, %BW regain was associated with the amount of percentage body fat lost during VLCD, which indicates that the more fat lost, the better the WM, suggesting a fat free mass‐sparing effect. Discussion: Characteristics such as the ability to increase dietary restraint and maintain this high level of restraint, fat free mass sparing, and a relatively high baseline BMI and fat mass were associated with successful long‐term WM (<10% regain after 2 years).     

Effect of Dominance,Reproductive State,and Group Size on Body Mass in Macaca radiata

Body mass can impact reproductive performance in males and females. In nonhuman primates the relationship is often mediated by dominance. We measured body mass monthly in a provisioned group of bonnet macaques (Macaca radiata) living at a Hindu temple. We also measured body mass on 3 occasions in a wild population of bonnet macaques. In the temple group, females that reproduced lost body mass, while females that did not reproduce gained body mass. Mass loss among females occurred primarily while they were nursing. Adult males from the temple group lost mass during the mating season and gained it during the non-mating season. Subadult males experienced less seasonal variation in body mass. Body mass and changes in mass were not related to dominance rank in either the temple or the forest group. Furthermore, maternal dominance rank did not affect infant mass. Females from the smallest forest group weighed significantly less than females from the two larger forest groups, which suggests intergroup competition in the population. Body mass was not related to dominance rank in a straightforward manner but may indirectly affect reproductive performance. The pattern of body mass change suggests that the period of lactation is critical for females and endurance rivalry is an important form of competition among males.     

Different physiological roles of serum leptin in the regulation of energy intake and thermogenesis between pregnancy and lactation in primiparous Brandt's voles (Lasiopodomys brandtii)

Reproduction, especially lactation, is associated with major metabolic adaptive changes. In this study, we investigated the metabolic changes and the roles of leptin during different periods of reproduction in primiparous Brandt's voles (Lasiopodomys brandtii). Energy intake, thermogenic capacity and serum leptin levels were examined in non-reproductive, mid pregnant, late pregnant, early lactating and peak lactating voles. Voles increased body mass by nearly 70% during late pregnancy compared to the non-breeding controls. The increase in body mass was mainly due to the increase in body fat mass which increased by 56%, and the growth of the reproductive tissues and digestive organs. Lactating voles decreased body fat by nearly 27% at peak lactation compared to the controls, and 53% compared to late pregnant voles. At the same time they increased food intake significantly. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) decreased significantly at peak lactation. Serum leptin increased significantly in the mid pregnancy, at a time when there was no increase in body fat, and remained at this high level in late pregnancy. Leptin levels decreased after parturition and reached a nadir at peak lactation. Serum leptin was negatively correlated with energy intake during lactation, but not during pregnancy. These data suggest that Brandt's voles adjust energy intake, thermogenic capacity and body reserves to match the high energy demands for reproduction. Hyperleptinemia, without decreased energy intake suggests a state of leptin resistance during pregnancy, and hypoleptinemia during lactation might act as a signal to stimulate energy intake.     

Effect of Age on Protein Conservation during Very-Low-Energy Diet in Obese Sprague-Dawley Rats

JOHNSON, JULIA A, CHOON-HIE YU, MEI-UIH YANG, F. XAVIER PI-SUNYER. Effect of age on protein conservation during very-low-energy diet in obese Sprague-Dawley rats. Obes. Res. 1998;6:448-157. Objective : To examine the effect of age on body protein losses occurring during severe energy restriction in obesity. Research Methods and Procedures : Weanling (young) Sprague-Dawley rats (YR) were fed a high fat (35% energy) diet (HFD) until mean body weight approached that of a group of chowfed retired breeder (aged) rats (AR). Both groups were then fed HFD for an additional 2 weeks, after which selected controls from YR and AR groups were killed for baseline carcass analysis. Remaining rats were fed a very-low-energy diet (VLED, 33% kcal of HFD) for 3 weeks and then killed for carcass analysis. Results : YR had greater fat stores before VLED, and lost proportionately more fat and less protein during VLED than did AR. Weight loss composition during VLED was 66.7% fat, 11.1% protein, and 22.2% water in YR, and 39.4% fat, 26.2% protein, and 34.3% water in AR. Greater YR fat loss during VLED* (70.6 ± 30.4 vs. 32.6 ± 29.1 g in AR; mean ± SD) was paralleled by significantly larger decreases in epididymal and retroperitoneal fat pad weights, mean adipocyte size, and lipoprotein lipase activity. Greater protein loss in AR (21.6 ± 13.9 g vs. 11.8 ± 10.7 g in YR) coincided with larger decreases in visceral organ weights and serum thyroxine and triiodothyronine. Energy expenditure changes during VLED were similar between groups. Discussion : Dietary obese young rats appear better able than aged rats to conserve body protein while losing body fat during severe energy restriction.