The effects of feeding regime on proximate body composition and patterns of energy deposition in juvenile Arctic charr, Salvelinus alpinus

Juvenile Arctic charr, Salvelinus alpinus , subjected to either food deprivation or restricted feeding showed reductions in relative sizes of both liver and viscera. With food deprivation, percentage lipid decreased and percentage water increased in the eviscerated carcass, which is in agreement with findings for several other fish species. Following transfer from a restricted to a satiation feeding regime, the relative sizes of both liver and viscera increased to levels exceeding those of fish fed continuously to satiation. At the end of the experiment the percentage liver lipid content of restricted-satiation fed fish was higher than in fish fed to satiation. These differences in energy deposition patterns were, however, not sufficiently large to produce marked differences at the whole animal level, since whole body lipid energy: protein energy ratios and energy utilization efficiencies were similar for restricted-satiation and satiation fed fish.     

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.     

Mechanisms of digestion in the marine herbivore, the luderick, Girella tricuspidata (Quoy and Gaimard)

The effect of feeding frequency on the mechanisms of digestion in the mucosa and contents of the gastrointestinal tract of the luderick, Girella tricuspidata (Quoy and Gaimard), was determined. Use was made of the variation in utilization frequency of Enteromorpha intestinalis by C. tricuspidata fed according to two different regimes to determine the importance of these digestive mechanisms in algal digestion.
The contents of the oesophagus and stomach of fish fed ad libitum were consistently acidic whilst those from fish deprived of food were highly variable and more alkaline. The contents of the pyloric caeca. intestine and rectum were slightly alkaline in both groups.
The number of microorganisms found in the digestive tract increased with a reduction in food availability. There was no significant cellulase activity in any of the animals tested.
Amylase and lipase were found in the pyloric caeca, intestine and rectum, but were not present in the oesophagus or stomach. Lipase activities were highly variable. Although some protease was found in the posterior portion of the gut, the majority of the activity occurred in the oesophagus and stomach.
Generally, amylase, lipase, and protease activities were unaffected by a change in the feeding regime of the fish from being fed ud libitum to being fed for a period of 24 h every 5 days. It is concluded that a reduced activity of enzymes that hydrolyse algal cell contents is not the reason for the lower utilization efficiency of food-deprived fish.
It is clear that the only difference in digestive mechanisms between fish fed ad libitum and fish fed infrequently is the variation in pH of the foregut. It is considered likely that the increased acidity of the foregut of animals fed ad Iibilum facilitates hydrolysis of the algal cell walls and allows greater utilization of algae by these fish.     

Pattern of hyperphagia in immature three-spined sticklebacks after short-term food deprivation

Juvenile three-spined sticklebacks Gasterosteus aculeatus were fed live enchytraeid worms, and mean daily ad libitum consumption in the absence of periods of deprivation was 11·7% of initial body weight. Then, six groups of five replicate fish were subjected to 1, 3 and 6 days without food. Each period of deprivation was followed by 1 day of ad libitum feeding. The sequential order of deprivations differed between groups. Over the sequence of deprivations and re-feedings, mean cumulative consumption did not differ between groups. Mean daily consumption was 19·8% of initial body weight after a 1-day deprivation, 22·3% after 3 days and 19·5% after 6 days. However, consumption in the 24 h after a given length of deprivation also depended on the prior history of deprivation. Specific growth rate over the experiment did not differ between groups. The results provide evidence for an effective regulation of appetite in growing sticklebacks.     

The stability of standard metabolic rate during a period of food deprivation in juvenile Atlantic salmon

Among juvenile Atlantic salmon Salmo salar either being fed ad libitum throughout a 3 month experiment or deprived of food in the middle month, food deprivation led to a decrease in SMR, which increased again once food was supplied ad libitum again. While the rank order of SMR among fish fed throughout remained relatively stable, that within the deprived group was inconsistent, suggesting that individual fish vary in their ability to reduce metabolic costs when food availability is low.     

Compensatory growth response in three-spined stickleback in relation to feed-deprivation protocols

Different protocols of food deprivation were used to bring two groups of juvenile three-spined sticklebacks Gasterosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum . One group experienced 1 week of deprivation then 2 weeks on maintenance rations. The second group experienced 1 week of ad libitum feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass of c . 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the three-spined sticklebacks had reached the reduced body mass. The compensatory response was sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipid-free dry mass. Hyperphagia and increased growth efficiency were present in the re-feeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature three-spined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts.     

Influence of alterations in meal frequency on lipogenesis and body fat content in the rat.

Rats were allowed to eat only 2 hr per day (meal-fed) or were fed ad libitum (nibbler) for 12 wk; another group of animals was meal-fed for 3 wk and then fed ad libitum (converted I) while the fourth group of rats (converted II) was meal-fed for 3 wk, allowed to nibble for the next 3 wk, meal-fed from the 6th to 9th wk and then returned to ad libitum feeding for the last 3 wk. Body fat gain and food efficiency was increased in converted I rats. The lipogenic capacity of adipose tissue from meal-fed rats was greater than observen meal-fed rats were reverted to ad libitum feeding whereas lipogenic activity increased rapidly when ad libitum fed rats were switched to meal-feeding.     

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.     

Growth performance and body composition in response to dietary protein and lipid levels in Nile tilapia (Oreochromis niloticus Linnaeus, 1758) subjected to normal and temporally restricted feeding regimes

A factorial experiment was designed to examine the effect on compensatory growth (CG) of Nile tilapia Oreochromis niloticus fed diets containing different protein and lipid levels under normal and temporally restricted feeding regimes. Four diets were formulated to contain either 30% or 36% crude protein, and 5% or 11% crude lipid. Triplicate replicates of each treatment were assigned to 24 150‐L tanks (20 fish/tank density). Fish (mean initial weight ± SD = 8.79 ± 0.34 g) were then fed either the normal feeding regime (thrice daily to apparent satiation) or the restricted regime (1 day feed deprivation followed by 3 days of feeding to apparent satiation) over a 44‐days study period. Fish receiving a diet under the restricted regime achieved weight gains (WG) comparable to fish consuming the diet containing 30% protein and 5% lipids under the normal feeding regime. Fish maintained on the restricted feeding regime exhibited reduced feed intake (FI), WG, feed efficiency ratio (FE), protein efficiency rate (PER) and hepatosomatic index versus fish on the normal feeding regime, except WG in fish fed the diet with 30% protein and 5% lipids. However, the resultant FI (85%~94%) was higher than the excepted 75% intake when fish were subjected to the restricted regime. Feeding 11% lipid diets led to improved FI, WG, FE, and PER compared to feeding the 5% lipid diets. Increased FI, WG, and FE, but reduced PER were observed in fish fed with 36% protein versus fish fed 30% protein. Fish receiving the 36% protein diets had lower whole‐body moisture and ash contents, but elevated whole‐body protein and lipid contents compared to those receiving the 30% protein diets. Whole‐body moisture contents were lower, but whole‐body protein, lipid and ash contents were higher in fish fed 11% lipid diets than in fish fed 5% lipid diets. There was an increase in whole‐body moisture content, but a decrease in protein and lipid content in response to the restricted feeding regime. Ash content was not affected by the feeding regime. The present study shows that Nile tilapia fed diets subjected to a restricted feeding regime exhibited growth comparable to those fed the diet at 30% protein and 5% lipid levels under a normal feeding regime. This positive effect was more pronounced in diets at a high protein level or in a combination of high protein and lipid levels.     

Effect of intermittent fasting followed by cold on growth, formation of reserves and energy metabolism in the golden hamster

Golden hamsters (Mesocricetus auratus) were subjected to intermittent fasting for six weeks, for three of which their environmental temperature was reduced to 4 degrees C. They were compared with a control group (fed ad libitum and kept at 22 degrees C), a group subjected six weeks only to intermittent fasting at 22 degrees C and a group fed ad libitum for six weeks, but exposed to a temperature of 4 degrees C after the third week. The effect of these various nutritional and temperature regimens on growth, on food consumption, on the formation of liver glycogen and lipid reserves and on energy metabolism was studied. Adaptation to cold raised the hamsters' food intake above the hyperphagia level observed during intermittent fasting. Cold and intermittent fasting acted synergically in raising basal oxygen consumption values and reducting the amount of body lipids. They acted antagonistically on the liver glycogen concentration; when they were used simultaneously, the effect of intermittent fasting preponderated.     

Benefits for dominant red deer hinds under a competitive feeding system: food access behavior, diet and nutrient selection

Social dominance is widely known to facilitate access to food resources in many animal species such as deer. However, research has paid little attention to dominance in ad libitum access to food because it was thought not to result in any benefit for dominant individuals. In this study we assessed if, even under ad libitum conditions, social rank may allow dominant hinds to consume the preferred components of food. Forty-four red deer hinds (Cervus elaphus) were allowed to consume ad libitum meal consisting of pellets of sunflower, lucerne and orange, and seeds of cereals, corn, cotton, and carob tree. The meal was placed only in one feeder, which reduced accessibility to a few individuals simultaneously. During seven days, feeding behavior (order of access, time to first feeding bout, total time spent feeding, and time per feeding bout) were assessed during the first hour. The relative abundance of each meal component was assessed at times 0, 1 and 5 h, as well as its nutritional composition. Social rank was positively related to the amount of time spent feeding during the 1(st) h (P = 0.048). Selection indices were positively correlated with energy (P = 0.018 during the 1(st) h and P = 0.047 from 1(st) to 5(th)) and fat (only during the 1(st) h; P = 0.036), but also negatively with certain minerals. Thus, dominant hinds could select high energy meal components for longer time under an ad libitum but restricted food access setting. Selection indices showed a higher selectivity when food availability was higher (1(st) hour respect to 1(st) to 5(th)). Finally, high and low ranking hinds had longer time per feeding bout than mid ones (P = 0.011), suggesting complex behavioral feeding tactics of low ranking social ungulates.     

Lipid mobilization during starvation in the rainbow trout, Salmo gairdneri Richardson, with attention to fatty acids

Rainbow trout, Salmo gairdneri , were fed pelleted food ad libitum for 35 and 50 days. Lipid deposits were determined in the viscera, liver and muscle (epaxial and hypaxial). Most of the lipid accumulated in the viscera, but the lipid content of liver and epaxial muscle also increased. Hypaxial muscle lipid content remained the same throughout the feeding period. Upon starving the fish for 27 and 48 days following 50 days of feeding, visceral lipid contributed most to energy metabolism among the depots investigated. Muscle also contributed a considerable share while the absolute amount derived from the liver was much smaller.
Patterns of fatty acid mobilization during starvation were also investigated. Saturated acids were preferentially mobilized from the viscera, resulting in a rise in the percentage of monoenes and polyunsaturates. In liver, the percentage of saturates remained relatively constant whereas the percentage of monoenes declined and polyunsaturates increased. In muscle, a substantial increase in saturates was caused by a decline in monoenes; polyunsaturate content remained constant. As a result of these shifts in relative fatty acid composition the U/S (unsaturates to saturates) ratio rose in viscera and liver and decreased in muscle. The UI (unsaturation index) responded in essentially the same way. Possible explanations for preferential fatty acid utilization are discussed in terms of energetics and structural relationships.     

Food- and light-entrainable oscillators control feeding and locomotor activity rhythms, respectively, in the Japanese catfish, Plotosus japonicus

Feeding and locomotor activities of the Japanese catfish Plotosus japonicus under solitary condition were recorded to identify mechanisms controlling these behaviours. In the absence of food, the catfish showed nocturnal locomotor activity, but no feeding activity. Under ad libitum food conditions, both feeding and locomotor activities occurred during the dark period and were synchronized with light/dark (LD) cycles. Feeding activity lasted for 11–24 days when food was stopped after ad libitum food availability. Restricted food during the light phase produced both food-anticipatory and light-entrainable feeding activity. Furthermore, this condition produced weak food-anticipatory and light-entrainable locomotor activity. Under the light/light (LL) condition, restricted food produced food-anticipatory feeding and locomotor activities, suggesting that a food-entrainable oscillator controls both feeding and locomotor activities. However, under the LL condition, light-entrainable feeding and locomotor activities were not observed, suggesting that a light-entrainable oscillator controls both feeding and locomotor activities. During a restricted food schedule, LD cycle shifts resulted in disrupted synchronization of feeding activity onset in three of the four fish, but one fish showed synchronized feeding activity. These results suggest that the food- and the light-entrainable oscillator may control feeding and locomotor activities, respectively.     

Effects of feeding time constraints on body mass regulation and energy expenditure in wintering dunlin (Calidris alpina)

We examined the effects of time-restricted feeding on regulationof body mass and activity energy expenditure in captive winteringdunlin (Calidris alpina) held in outdoor aviaries at TomalesBay, California. In the first of two experiments, we comparedbirds under 24 h : 24 h (fasting : ad libitum feeding) foodrestriction with controls under continuous ad libitum feeding. In the second experiment, we compared birds under 24 h : 6 h: 12 h : 6 h (fasting : ad libitum : fasting : ad libitum)food restriction with birds under 24 h : 24 h food restriction.We estimated total energy expended on activities from dailymass balance using an additive model based on measures of grossenergy intake, thermoregulation, basal metabolism, and a sensitivity analysis of gross utilization efficiency and energy densityof reserve body tissue. Dunlin under 24 h : 24 h food restrictionovercompensated for body mass lost while fasting, increasingtheir body mass relative to controls fed ad libitum. Dunlinunder 24 h : 6 h : 12 h : 6 h food restriction were unable to recover body mass lost during the first fasting day. Whenallowed to feed, food-restricted birds reduced the amount ofenergy spent on being active and increased food intake andenergy storage relative to controls, but when forced to fast,they increased their activity energy expenditure. These patterns suggest winter body mass regulation consistent with the behaviorsof free-living dunlin in winter.     

Effect of food synchronization on the circadian rhythm of bone marrow and thymus lipids in rats

Young male Wistar rats reared under standard laboratory conditions with a 12:12 h light:dark regimen were fed ad libitum or were allowed access to food for only 2 h in the first half of the light or the dark part of the day. In rats fed ad libitum, marked circadian oscillation of the bone marrow triacylglycerol and phospholipid concentration and oscillation of the same fractions in the thymus were found. The restricted feeding time raised the triacylglycerol concentration in the bone marrow, but did not noticeably affect the time course of the circadian curves. The mean lipid values in the thymus of animals with a shortened feeding time did not alter, but the acrophase of the two basic fractions shifted.     

Zinc deficiency affects the composition of the rat adrenal gland

The response of the adrenal gland to zinc deficiency was examined in male weanling rats. In comparison with decapsulated adrenals from ad libitum fed controls, glands from zinc deficient rats had greater relative weight (mg/g body wt), DNA concentration, and total lipid and cholesterol concentrations as well as a smaller protein/DNA ratio. Several of these differences (protein/DNA and cholesterol concentration) could be attributed to the inanition accompanying zinc deficiency, as zinc deficient values were similar to those of pair fed controls. Values for total DNA and protein concentration were similar for all groups. Electron micrographs of the zona fasciculata showed a small number of lipid droplets in the adrenals from ad libitum fed controls, an increase in lipid droplets from pair fed controls, and an even more striking increase in lipid droplets from the zinc deficient adrenals. The increased adrenal lipid composition in the zinc deficient group may be secondary to enhanced steroidogenesis or a zinc deficiency-induced defect of lipid metabolism.     

Effects of rearing temperature and level of food intake on organ size and tissue composition in piglets

Piglets are particularly susceptible to cold and nutritional stress because of their poor insulation and low body fat. The purpose of this study was to examine how ambient temperature and level of food intake affect development in piglets. Thirty-two piglets were reared individually from 14 to 56 days of age in either a cold (10 degrees C) or a warm (35 degrees C) environment. Two feeding regimens, restricted and ad libitum, were used to assess the effect of food intake on organ mass. The ad libitum fed pigs in both environments gained weight at the same rate. Paired t-tests of organ weights of ad libitum fed pigs revealed that the mass of the heart, liver, kidneys, stomach, and small intestine, and total nitrogen and the length of the small intestine were greater in cold-reared than in warm-reared littermates of the same body weight. The skin mass and total fat mass, the lengths of the body, extremities, and individual long bones, and the total surface area were greater in warm-reared than in cold-reared individuals. A regression analysis showed body weight was the most important determinant of size for all tissues measured except fat mass, which was affected slightly more by rearing temperature. Of the organs and tissue components that differed in size in warm- and cold-reared pigs, heart, kidney, stomach, skin, nitrogen, and fat mass, and small intestine length and surface area were generally affected more by rearing temperature than by level of food intake. Liver and small intestine mass and femur length were affected more by level of food intake.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of feeding frequency on consumption of food,absorption efficiency,and gonad production in the sea urchin Lytechinus variegatus

The frequency of feeding in the field is variable in sea urchins, ranging from nearly continuous to diel or intermittent. It is essential to know the effect of feeding interval on physiological and metabolic processes to understand the basis for production. Lytechinus variegatus (50 mm horizontal diameter) were collected in January 1999 and held in closed-circuit aquaria at 25 degrees C and 35 per thousand salinity. After 9 days without food, individuals were fed one of three treatments: food available ad libitum, food available for 1 day every 2 days or food available for 1 day every 4 days for 28 days. The rate of food consumption per day of all individuals was high the first week of feeding. It then decreased to a lower, constant rate in those fed ad libitum but remained high in those fed one day every 2 or 4 days. The total amount eaten was directly related to frequency of feeding. The apparent dry matter digestibility (absorption efficiency) did not vary with frequency of feeding. As the total amount of energy absorbed was directly related to the frequency of feeding, the increase in the rate of food consumption does not compensate for a decrease in frequency of feeding. Gonad production efficiency was directly related to frequency of feeding. Gonad gross production (assimilation) efficiencies were 8.4, 3.9 and 3.4% for individuals fed every day, or fed one day every 2 and 4 days, respectively. The corresponding gonad net assimilation efficiencies were 12.5, 5.5, and 4.8%. A decrease in frequency of food availability results in use of a greater proportion of the food consumed for maintenance and less for gonad production.     

The adrenocortical response of tufted puffin chicks to nutritional deficits

In several seabirds, nutritional state of a nest-bound chick is negatively correlated with the activity of its hypothalamus–pituitary–adrenal (HPA) axis. Increased corticosterone (cort) secretion has been shown to facilitate changes in behavior that allow hungry chicks to obtain more food from parents. However, if parents are not willing/able to buffer their young from temporary food shortages, increased cort secretion could be detrimental to undernourished chicks. In a system where parents are insensitive to chick demands, low benefits and high costs of activation of the HPA-axis in hungry chicks should lead to a disassociation of the nutritional state of the young and the activity of its HPA-axis. We tested this novel hypothesis for the tufted puffin (Fratercula cirrhata), a seabird with intermittent provisioning of a nest-bound semi-precocial chick. We examined the HPA-axis activity of captive chicks exposed to the following: (1) a short-term (24 h) food deprivation; and (2) an array of prolonged (3 weeks) restrictions in feeding regimens. We found that in response to a short-term food deprivation chicks decreased baseline levels of cort and thyroid hormones. In response to prolonged restrictions, food-limited chicks exhibited signs of nutritional deficit: they had lower body mass, endogenous lipid reserves, and thyroid hormone titers compared to chicks fed ad libitum. However, baseline and maximum acute stress-induced levels of cort were also lower in food-restricted chicks compared to those of chicks fed ad libitum. These results support a major prediction of the study hypothesis that puffin chicks suppress HPA-axis activity in response to short- and long-term nutritional deficits. This physiological adaptation may allow a chick to extend its development in the nest, while eluding detrimental effects of chronic cort elevation.     

Variation in the ovarian and plasma progesterone and estradiol levels of the domestic hen during a pause in laying

Little is known about the physiological events occurring in the chicken ovary during a pause in laying, therefore the aim of the present study was to examine changes in sex steroid concentration in the follicle wall and blood plasma during cessation of egg laying. The experiment was performed on laying Isa Brown hens. Control hens were fed ad libitum whereas the experimental ones were subjected to a pause in laying by complete food deprivation for 5 days and water deprivation on 3 day followed by feeding every second day up to 9 day and then ad libitum. Blood samples were taken from the wing vein each day. The hens were decapitated on day 3, 6, 9, and 16. The ovary was isolated and the following follicles were dissected: white (1-2; 2-4; 4-6; 6-8 mm) and yellow preovulatory ones (F1-F3). Progesterone and estradiol were measured in the follicle wall and blood plasma by RIA methods. The hens stopped egg laying on day 4 and began egg restoration on day 14 of the experiment. Cessation of egg laying was preceded by a decrease in estradiol and progesterone levels in the ovary as well as in the blood plasma. The plasma level of these steroids began to increase 7 days before the start of egg restoration. Autopsy of the ovary showed that the atrophy of the chicken yellow preovulatory follicles during the pause in laying was accompanied by a significant increase in the total number of white follicles.