Refuge use by fish as a function of body length-related metabolic expenditure and predation risks

Theory predicts that staying in a refuge has benefits in terms of predator avoidance and costs in terms of lost feeding opportunities. In this study, we investigated how the relative importance of these costs and benefits changes with increasing body length. This is of particular interest in animals such as fish, which show continuous growth throughout their lives. Our results suggest that larger fish are subject to lower predation risks and are less affected by food deprivation than small fish, with fish decreasing their responses to food-deprivation treatments more strongly with increasing body length than to predation treatments. This may explain our observation that large fish emerged later from a refuge than small ones and spent shorter times outside the refuge. The key role of differential responses to food deprivation was further illustrated by the finding that the relative weight loss of individual fish was strongly correlated with a reduction in hiding time even in the absence of body length differences. The importance of inter-individual differences in metabolic rates for the decision-making behaviour of animals is discussed.     

Effect of cycles of feed deprivation on growth and food consumption of immature three-spined sticklebacks and European minnows

Individual juvenile three-spined sticklebacks Gasterosteus aculeatus and European minnow Phoxinus phoxinus , from sympatric populations, were subjected to four cycles of 1 week of food deprivation and 2 weeks of ad libitum feeding. Mean specific growth rate during the weeks of deprivation was negative and did not differ between species. The three-spined stickleback showed sufficient growth compensation to recover to the growth trajectory shown by control fish daily fed ad libitum . The compensation was generated by hyperphagia during the re-feeding periods, and in the last two periods of re-feeding, the gross growth efficiencies of deprived three-spined sticklebacks were greater than in control fish. The expression of the compensatory changes in growth and food consumption became clearer over the successive periods of re-feeding. The European minnow developed only a weak compensatory growth response and the mass trajectory of the deprived fish deviated more and more from the control trajectory. During re-feeding periods, there were no significant differences in food consumption or gross growth efficiency between control and deprived European minnows. The differences between the two species are discussed in terms of the possible costs of compensatory growth, the control of growth and differences in feeding biology.     

Repeated predatory attacks and multiple decisions to come out from a refuge in an alpine lizard

Prey often respond to predator presence by increasing theiruse of refuges. However, because the use of refuges may entailseveral costs, the decision of when to come out from a refugeshould be optimized. In some circumstances, if predators remainwaiting outside the refuge and try new attacks or if predator density increases, the prey may suffer successive repeated attacksin a short time. Successive attacks may represent an increasein the risk of predation, but the costs of refuge use alsomay increase with time spent in the refuge. Thus, prey shouldmake multiple related decisions on when to emerge from the refuge after each new attack. We simulated in the field repeatedpredatory attacks to the same individuals of the lizard Lacertamonticola and specifically examined the variation in successivetimes to emergence from a refuge under different thermal conditions(i.e., different costs of refuge use). The results showed thatrisk of predation but also thermal costs of refuge use affectedthe emergence decisions. Lizards increased progressively theduration of time spent in the refuge between successive emergencetimes when the costs of refuge use were lower, but tended tomaintain or to decrease the duration of time spent in the refugebetween successive emergence times when cost of refuge useincreased. Additionally, lizards that entered the refuge withhigher body temperatures had overall emergence times of longer duration. Optimization of refuge use and flexibility in theantipredator responses might help lizards to cope with increasedpredation risk without incurring excessive costs of refugeuse.     

Prolonged feed deprivation does not permanently compromise digestive function in migrating European glass eels Anguilla anguilla

The effects of prolonged feed deprivation (40 days at 18° C) and re-feeding (30 days) on body mass, growth and the activity of selected pancreatic and intestinal enzymes were evaluated in migrating European glass eels Anguilla anguilla by comparison with a control group fed to satiation with hake Merluccius merluccius roe for the duration of the experiment. Feed deprivation resulted in mass loss and a reduction in digestive function, as revealed by a decrease in the total and specific activities of pancreatic (trypsin and α-amylase) and intestinal brush border (alkaline phosphatase and leucine aminopeptidase) enzymes. The total activity of intestinal brush border enzymes diminished after 5 days of feed deprivation, whereas that of pancreatic enzymes did not decrease until 10 days, indicating that the intestine is more sensitive to feed deprivation than the pancreas. Re-feeding A. anguilla that were starved for 40 days resulted in compensatory growth, with specific growth rates that were 2·6 times higher than the control group. This compensatory growth was associated with the recovery of trypsin and intestinal brush border enzyme activities, which were restored to control levels within 5 days of re-feeding. The ability to maintain pancreatic enzyme activity during 40 days of feed deprivation, and rapidly recover capacity for protein digestion upon re-feeding, would enable A. anguilla at this glass eel stage to withstand periods without food but rapidly provide amino acids for protein synthesis and growth when suitable food was available.     

The regulation of endogeneous energy stores during starvation and refeeding in the somatic tissues of the golden perch

Adult golden perch Macquaria ambigua were fed to satiety, starved for up to 210 days, or starved for 150 days then fed to satiety for 60 days to investigate the utilization of energy stores in response to food deprivation and re-feeding. Golden perch sequentially mobilize energy from hepatic tissue, extra-hepatic lipid, and finally muscle components in response to food deprivation. The relative size of the liver was significantly reduced by 30 days after the onset of food deprivation due to the simultaneous mobilization of lipid, protein and glycogen reserves. These stores were renewed rapidly within 30 days by satiety feeding. Mobilization of lipid stores in perivisceral fat bodies occurred between 30 and 60 days of food deprivation. These deposits were also renewed upon re-feeding, although not as rapidly as liver reserves. The glycogen content of the epaxial muscle was reduced by the 60th day of food deprivation but subsequently increased indicating the mobilization of other energy reserves. The concentration of muscle lipid decreased after 90 days of food deprivation. The only significant response in body composition observed in the fish fed to satiety throughout the study was an increase in the relative size of the perivisceral fat bodies. The results of this study suggest that golden perch are well adapted to cope with extended periods of food deprivation, storing energy as perivisceral fat when food is readily available and having a clearly sequential process for mobilizing energy when food is scarce which largely protects the integrity of the musculature.     

When to Come Out from a Refuge: Balancing Predation Risk and Foraging Opportunities in an Alpine Lizard

Prey often respond to predator presence by increasing their use of refuges, but because this strategy may be costly, the decision regarding when to come out from a refuge should be optimized. The loss of foraging opportunities may be one of the main costs when safer microhabitats (i.e. refuges) are also the poorest in terms of their foraging profitability. We present the results of an experimental field study to test whether emergence times from a refuge of the Iberian rock lizard, Lacerta monticola, vary as a function of expected foraging opportunities and level of satiation of the lizard. As predicted, short‐term fluctuations in availability of food influenced emergence times; when a lizard had just detected some food in the recent past, emergence times decreased greatly, because the loss of opportunities for foraging increased costs of refuge use. Furthermore, the characteristics and success of the encounter with food, nutritional state of lizards, and the added possibility of capturing new food items influenced the duration of hiding times. Therefore, foraging requirements and avoidance of predators may be conflicting demands that L. monticola lizards balance by modifying the duration of time spent in refuges.     

The effects of food deprivation and re-feeding on bovine adipose-tissue glycogen synthase.

Bovine adipose-tissue glycogen metabolism was studied during food deprivation and re-feeding. Changes in the specific activity of adipose-tissue glycogen synthase paralleled changes in tissue glycogen content: both parameters increased during food deprivation and remained so during the first 10 days of re-feeding. The values for the A0.5 (activation constant) for glucose 6-phosphate of the freshly isolated enzyme from adipose tissue from fed and starved steers were 2.9 +/- 0.1 mM and 0.90 +/- 0.05 mM respectively. Additionally, whereas incubation of adipose-tissue extracts from fed steers did not activate endogenous glycogen synthase (through a presumed phosphoprotein phosphatase mechanism), the enzyme from starved or re-fed (up to 3 days re-feeding) steers was reversibly activated as measured by changes in the value for the A0.5 for glucose 6-phosphate. Thus activation of bovine adipose-tissue glycogen synthase during food deprivation appears to be related to expression of glycogen synthase phosphatase activity. These effects of food deprivation on bovine glycogen metabolism contrast markedly with the effects observed in rat adipose tissue.     

Do random fluctuations in the intervals between feeding affect growth rate in juvenile three-spined sticklebacks?

This study measured the effects of regular and irregular intervals between feeds on the growth performance of juvenile Gasterosteus aculeatus . The experimental period was 21 days at 14) C and photoperiod of 10L: 14D. The fish were housed individually. The control fish received a constant ration every day. Fish on a constant interval were fed on days 1, 5, 9, 13, 17 and 21. Fish on a random regime were fed with the same average interval between feedings, but the interval varied randomly between 1 and 5 days. The rations were calculated so that over the 21-day period, all fish were supplied with the same total quantity of food. The two ration levels were: 2% (maintenance ration) and 6% of the initial body weight per day. At a given ration, the feeding interval had no significant effect on specific growth rate, RNA/DNA ratio and lipid contents. The percentage dry matter was slightly, but significantly lower in treatment groups than in the control group. Groups receiving a mean 2% ratio consumed all the food supplied. At a mean ration of 6%, the control group ate 100%, the regular interval group 95·4% and the irregular interval 98·3% of the total food supplied. For the temporal patterns of feeding used, the fish were able to adjust their food intake, when food become available, to compensate for short periods of food deprivation and maintain their growth performance except for a decrease in dry matter content.     

Increased feeding and food hoarding following food deprivation are associated with activation of dopamine and orexin neurons in male Brandt's voles

Small mammals usually face energetic challenges, such as food shortage, in the field. They have thus evolved species-specific adaptive strategies for survival and reproductive success. In the present study, we examined male Brandt's voles (Lasiopodomys brandtii) for their physiological, behavioral, and neuronal responses to food deprivation (FD) and subsequent re-feeding. Although 48 hr FD induced a decrease in body weight and the resting metabolic rate (RMR), such decreases did not reach statistical significance when compared to the control males that did not experience FD. During the first 2 hr of re-feeding following 48 hr FD, voles showed higher levels of feeding than controls. However, when permitted to hoard food, FD voles showed an increase in food hoarding, rather than feeding, compared to the controls. Further, both feeding and food hoarding induced an increase in neuronal activation, measured by Fos-ir, in a large number of brain areas examined. Interestingly, feeding and food hoarding also induced an increase in the percentage of tyrosine hydroxylase immunoreactive (TH-ir) cells that co-expressed Fos-ir in the ventral tegmental area (VTA), whereas both FD and feeding induced an increase in the percentage of orexin-ir cells that co-expressed Fos-ir in the lateral hypothalamus (LH). Food hoarding also increased orexin-ir/Fos-ir labeling in the LH. Together, our data indicate that food-deprived male Brandt's voles display enhanced feeding or food hoarding dependent upon an environmental setting. In addition, changes in central dopamine and orexin activities in selected brain areas are associated with feeding and hoarding behaviors following FD and subsequent re-feeding.     

The effect of starvation and subsequent feeding on the hepatocytes of Chanos chanos (Forsskal) fingerlings and fry

Excised liver sections of the milkfish, Chanos chanos , fry and fingerlings were studied by transmission electron microscopy. The hepatocytes underwent marked ultrastructural alterations in response to food deprivation of 10-day starvation for fry and 2 months for the fingerlings. The prominent features characterizing the hepatocytes of starved fish were: a reduction of cell and nucleus size; apparent loss of nucleoli; condensation of chromatin material in fry; loss of stored glycogen; reduction of ER profiles; increase in the number of electron-dense bodies containing large amounts of iron in fingerlings; and an increase in mitochondrial size. These changes were reversible following short periods of re-feeding, i.e. 2 days for fry and 4 days for fingerlings, using natural food for the fry and formulated diet for the fingerlings.     

Genetic variability in residual feed intake in rainbow trout clones and testing of indirect selection criteria (Open Access publication)

Little is known about the genetic basis of residual feed intake (RFI) variation in fish, since this trait is highly sensitive to environmental influences, and feed intake of individuals is difficult to measure accurately. The purpose of this work was (i) to assess the genetic variability of RFI estimated by an X-ray technique and (ii) to develop predictive criteria for RFI. Two predictive criteria were tested: loss of body weight during feed deprivation and compensatory growth during re-feeding. Ten heterozygous rainbow trout clones were used. Individual intake and body weight were measured three times at threeweek intervals. Then, individual body weight was recorded after two cycles of a three-week feed deprivation followed by a three-week re-feeding. The ratio of the genetic variance to the phenotypic variance was found high to moderate for growth, feed intake, and RFI (VG/VP = 0.63 ± 0.11, 0.29 ± 0.11, 0.29 ± 0.09, respectively). The index that integrates performances achieved during deprivation and re-feeding periods explained 59% of RFI variations. These results provide a basis for further studies on the origin of RFI differences and show that indirect criteria are good candidates for future selective breeding programs.     

西伯利亚鲟在高温下饥饿后的补偿生长

在高温(29±1)℃下将西伯利亚鲟幼鱼(21.61±0.03)g饥饿0(对照)、6、12和18d后恢复摄食3周, 研究摄食、生长和鱼体组成的变化。结果表明, 经过不同程度饥饿的鱼体重均显著低于对照组(P0.05), 而饥饿18d(S18组)的鱼体重显著低于对照(P0.05)。在饥饿过程中,鱼体脂肪含量和肝脏肝糖原含量下降的同时, 各饥饿组的灰分含量上升, 但仅S18组与对照差异显著(P0.05)。结果表明, 西伯利亚鲟在高温下表现出完全补偿现象, 且是通过同时提高摄食率和饲料效率来实现补偿生长的, 因此在夏季高温时对鲟鱼进行一段时间适度的饥饿可以在不影响生长和体成分的前提下节约饲料成本, 减少因过量投饵而引起的环境污染。       

Liver histopathology and accumulation of melano-macrophage centres in Hoplias malabaricus after long-term food deprivation and re-feeding

In the Neotropical traíra Hoplias malabaricus , hepatocyte surface area declined after 30 days of fasting due to reserve utilization. Changes in normal organization of liver were not confirmed until 180 days of fasting. Severe histopathological changes occurred after 240 days. Pigment accumulation in the hepatocytes and increase in number and size (surface area) of melano-macrophage centres (MMC) were also verified during long-term food deprivation. The melano-macrophages were rich in ferric compounds, probably haemosiderin. This suggests that the activity of hepatic macrophages is related to the intense erythrocyte degradation that occurred in traíra following long-term food deprivation. After re-feeding for 30 days, the liver presented a partial restoration, but the large MMC remained. When compared to the respective starved group, the hepatocytes of re-fed fish increased in size, revealing recovering cell activity and storage of some energy reserves.     

Effects of starvation,re-feeding and timing of food supply on daily rhythm features of gut melatonin in carp (Catla catla)

Influences of starvation, re-feeding and time of food supply on daily rhythm features of melatonin (5-methoxy-N-acetyltryptamine) and its key regulator AANAT (arylalkylamine N-acetyltransferase) protein in the gut tissues were separately evaluated in carp Catla catla. The first experiment was aimed at demonstration of duration dependent effects of starvation and re-feeding after starvation on the daily profiles and rhythm features of gut melatonin and AANAT. Accordingly, juvenile carp were randomly distributed in three groups, which were (a) provided with balanced diet daily at a fixed time, that is, 10:00 clock hour or zeitgeber time (ZT) 4 (control), or (b) starved (for 2-, 4-, 6- or 8 days), or (c) initially starved for 8 days and then re-fed (for 2-, 4-, 6-, 8-, 12- or 16 days) daily with the same food and at the time (ZT4) used for control fish. The carp in each group were sampled for collection of gut tissues at six different time points at a regular interval of 4?h in a daily cycle. In another experiment, the influences of timing of food supply were separately examined in four fish groups, which were provided with a fixed amount of food once daily either at 06:00 or 12:00 or 18:00 or 24:00 clock hour corresponding to ZT0 or ZT6 or ZT12 or ZT18, respectively, for 7 days before sampling at 12 different time points with a regular interval of 2?h in a 24-h cycle. The study revealed a gradual increase in the mesor and amplitude values of melatonin and AANAT in gut with the progress of starvation till their values reached maximum at day-6 and remained steady thereafter. In contrast, re-feeding of 8-day starved fish resulted in a sharp decrease in their mesor and amplitude values after 2 days and then followed by a steady-state increase till re-attainment of their values close to control fish at the end of 16 days. The acrophase of these gut variables in each control, starved and re-fed fish was noted mostly at midday or ZT6. However, the results of another experiment demonstrated that a shift of food supply time led to a shift in their acrophase. The amount of residual food in the gut lumen in each, but not starved, fish by showing a significant positive correlation independently with the gut levels of melatonin and AANAT also indicated possible role of food as the synchronizer for their daily rhythms. Collectively, it appears reasonable to argue that daily profiles of gut melatonin and AANAT are strongly influenced by the availability of food, while their daily rhythm features seem to be dependent mostly on the time of food supply in carp.     

Interacting effects of predation risk and food availability on larval anuran behaviour and development

Age and size at metamorphosis are two important fitness components in species with complex life cycles. In anurans, metamorphic traits show remarkable phenotypic plasticity, especially in response to changes in growth conditions. It is also possible that the perception of risk directly determines changes in larval period and the size of metamorphs. This study examines how the perception of predation risk affects the timing of and size at metamorphosis in common frogs (Rana temporaria). I raised tadpoles at two risk levels (fish-conditioned water or unconditioned water) crossed with the availability or lack of food at night (all tadpoles had food available in the day). Tadpoles reacted to chemical cues from predatory fish by decreasing activity. A novel behavioural result was a predation×food interaction effect on refuge use, which also accounted for most of the predator main effect: predation risk only caused increased refuge use in the night-starved treatment. Despite these behavioural modifications, the perception of predation risk did not affect growth rate and mass at metamorphosis in a simple way: the effects of food regime on growth and size at metamorphosis were dependent on the level of predation risk as revealed by significant predation×food interaction effects. Tadpoles who had food withheld at night metamorphosed at the smallest size, suggesting a negative relationship between size at metamorphosis and refuge use. Tadpoles raised in fish-conditioned water had longer larval periods than those in unconditioned water, but these differences were significant only if food was available at night. These results conflict with the hypotheses that tadpoles should reduce their larval period or growth rates (and hence metamorphose at a smaller size) as the risk of predation increases. In contrast to predation risk, food availability strongly affected the length of the larval period: night-starved tadpoles metamorphosed relatively early with or without fish stimulus. Thus, early metamorphosis resulted from periods of low food availability, but not from a heightened ”perceived risk” of predation. This example counters the hypothesis of acceleration of the developmental rate (which shortens the time to metamorphosis) as a mechanism to escape a risky environment. Received: 18 August 1999 / Accepted: 10 January 2000     

Erythrocyte senescence and haematological changes induced by starvation in the neotropical fish traíra, Hoplias malabaricus (Characiformes, Erythrinidae)

Adult specimens of traira (Hoplias malabaricus Bloch) were subjected to long-term starvation (30 to 240 days) and re-fed for 30 days after 90 and 240 days of food deprivation. Counting of immature erythrocytes in peripheral blood showed that erythropoiesis decreased significantly during the first 30 days of food deprivation. The results suggest that a process of senescence takes place in the pre-existent red blood cells and that the cells are not replaced during starvation. After 240 days of starvation, H. malabaricus had a significantly reduced number of red blood cells, causing changes in hematocrit and blood indices (mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration). Furthermore, during this period, the fish presented leukopenia (lymphocytopenia) and thrombocytopenia. After re-feeding, the number of leukocytes and thrombocytes recovered, but the red blood cell number remained reduced and there was a significant increase in abnormal red cell nuclei.     

Acute decrease in vitellogenin synthesis by deprivation of food and water in laying hens

Vitellogenin synthesis during a decrease in egg production caused by depriving food and water was investigated in Single Comb White Leghorn hens. They were transferred from long days of 14L: 10D to short days of 10L: 14D 5 days before food and water deprivation. Then food was deprived for 5 days and water for 2 days. The body weight was markedly decreased by the treatment and reached its minimum after 5 days. The egg production rate which was 85% before the treatment was nil after 4 days. On day 3 the circulating vitellogenin concentrations, measured by a newly established RIA system, was markedly decreased by deprivation of food and water to 22% of the pretreatment level. The concentrations remained less than 10% during cessation of egg laying. Serum luteinizing hormone (LH) and progesterone concentrations decreased gradually, but estradiol 17 beta (E2) decreased abruptly. This acute decrease closely coincided with the decrease in egg production and the weight of the oviduct and ovary. These concentrations were gradually increased after day 16 and returned to the normal level after 46 days. Circulating thyroxine (T4) and triiodothyronine (T3) concentrations gradually increased from the beginning of the change in the day length and peaked on day 7 or 9, whereas reverse (r)T3 rapidly increased. The concentrations again decreased at the beginning of molting which occurred later due to the deprivation of food and water. Thus, these results demonstrated for the first time that the decrease in egg production induced by deprivation of food and water closely related to the decrease in vitellogenin synthesis as well as gonadal and pituitary functions. Further, recovery of egg production was coupled with the increase in the ovary and oviduct weight, and circulating LH, E2, progesterone, and vitellogenin.     

Costs of Refuge Use Affect Escape Decisions of Iberian Rock Lizards Lacerta monticola

Theoretical models of anti-predator escape behaviour suggest that prey may adjust their escape response such that the optimal flight distance is the point at which the costs of staying exceed the costs of fleeing. Anti-predatory decisions should be made based also on consequences for long-term expected fitness, such as the costs of refuge use. For example, in lizards, the maintenance of an optimal body temperature is essential to maximize physiological processes. However, if unfavourable thermal conditions of refuges can decrease the body temperature of lizards, their escape decision should be influenced by refuge conditions. Analyses of the variation in flight distances and emergence latency from a refuge for the lizard Lacerta monticola under two different predation risk levels, and their relationship with the thermal environment, supported these predictions. When risk increased, lizards had longer emergence latencies, and thus costs of refuge use increased (a greater loss of time and body temperature). In the low-risk situation, lizards that were farther from the refuge had longer flight distances, whereas thermal conditions were less important. When risk increased, lizards had longer flight distances when refuges were farther off, but also when the external heating rate and the refuge cooling rate were lower. The results suggest that, in addition to the risk of predation, expected long-term fitness costs of refuges can also affect escape decisions.     

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.     

完全或部分的食物剥夺对中华鳖(Pelodiscus sinensis)幼体补偿生长反应的影响:生长率的时间变化模式与体组成的变化

为了探究中华鳖（Pelodiscus sinensis）幼体的补偿生长能力,我们对中华鳖幼鳖（平均湿重9．56g）进行如下6种处理：饥饿0（对照）、1、2、3、4周,或者食物限制4周,即只投喂体湿重百分之一的食物;然后对各组进行饱食处理直到10周的实验结束为止。结果发现在饱食期的第一周各饥饿处理组的特殊生长率均显著高于对照组（P〈0．05）,但是终体重均没有赶上对照组。当饥饿或食物限制结束时,脂肪含量随着饥饿期的延长而降低,灰分和水分则表现出相反的变化趋势：脂肪含量显著低于对照（P〈0．05）,而灰分和水分则显著高于对照（P〈0．05）。蛋白含量则没有显著变化（P〉0．05）。实验结束时,除了灰分外（P〈0．05）,其他个体组成指标均恢复到对照组的水平。以上结果表明中华鳖幼体在饥饿胁迫下首先利用脂肪作为主要能源以维持生存,以及在该研究条件下完全的食物剥夺可以诱发其部分补偿生长反应．而部分食物剥夺则不能诱发此反应。