The Nutritional Geometry of Resource Scarcity: Effects of Lean Seasons and Habitat Disturbance on Nutrient Intakes and Balancing in Wild Sifakas

Animals experience spatial and temporal variation in food and nutrient supply, which may cause deviations from optimal nutrient intakes in both absolute amounts (meeting nutrient requirements) and proportions (nutrient balancing). Recent research has used the geometric framework for nutrition to obtain an improved understanding of how animals respond to these nutritional constraints, among them free-ranging primates including spider monkeys and gorillas. We used this framework to examine macronutrient intakes and nutrient balancing in sifakas (Propithecus diadema) at Tsinjoarivo, Madagascar, in order to quantify how these vary across seasons and across habitats with varying degrees of anthropogenic disturbance. Groups in intact habitat experience lean season decreases in frugivory, amounts of food ingested, and nutrient intakes, yet preserve remarkably constant proportions of dietary macronutrients, with the proportional contribution of protein to the diet being highly consistent. Sifakas in disturbed habitat resemble intact forest groups in the relative contribution of dietary macronutrients, but experience less seasonality: all groups’ diets converge in the lean season, but disturbed forest groups largely fail to experience abundant season improvements in food intake or nutritional outcomes. These results suggest that: (1) lemurs experience seasonality by maintaining nutrient balance at the expense of calories ingested, which contrasts with earlier studies of spider monkeys and gorillas, (2) abundant season foods should be the target of habitat management, even though mortality might be concentrated in the lean season, and (3) primates’ within-group competitive landscapes, which contribute to variation in social organization, may vary in complex ways across habitats and seasons.     

The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L)

The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF). The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat), interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L.), a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose’s self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i) maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii) increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality.     

The ‘omnivorous badger dilemma’: towards an integration of nutrition with the dietary niche in wild mammals

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Macronutrient balancing in free‐ranging populations of moose

At northern latitudes, large spatial and temporal variation in the nutritional composition of available foods poses challenges to wild herbivores trying to satisfy their nutrient requirements. Studies conducted in mostly captive settings have shown that animals from a variety of taxonomic groups deal with this challenge by adjusting the amounts and proportions of available food combinations to achieve a target nutrient balance. In this study, we used proportions‐based nutritional geometry to analyze the nutritional composition of rumen samples collected in winter from 481 moose (Alces alces) in southern Sweden and examine whether free‐ranging moose show comparable patterns of nutrient balancing. Our main hypothesis was that wild moose actively regulate their rumen nutrient composition to offset ecologically imposed variation in the nutritional composition of available foods. To test this, we assessed the macronutritional composition (protein, carbohydrates, and lipids) of rumen contents and commonly eaten foods, including supplementary feed, across populations with contrasting winter diets, spanning an area of approximately 10,000 km². Our results suggest that moose balanced the macronutrient composition of their rumen, with the rumen contents having consistently similar proportional relationship between protein and nonstructural carbohydrates, despite differences in available (and eaten) foods. Furthermore, we found that rumen macronutrient balance was tightly related to ingested levels of dietary fiber (cellulose and hemicellulose), such that the greater the fiber content, the less protein was present in the rumen compared with nonstructural carbohydrates. Our results also suggest that moose benefit from access to a greater variety of trees, shrubs, herbs, and grasses, which provides them with a larger nutritional space to maneuver within. Our findings provide novel theoretical insights into a model species for ungulate nutritional ecology, while also generating data of direct relevance to wildlife and forest management, such as silvicultural or supplementary feeding practices.     

Macronutrient Optimization and Seasonal Diet Mixing in a Large Omnivore,the Grizzly Bear: A Geometric Analysis

Nutrient balance is a strong determinant of animal fitness and demography. It is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. These relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. Here we apply geometric models to understand how the nutritional compositions of foods available to an omnivorous member of the order Carnivora, the grizzly bear (Ursus arctos L.), relate to optimal macronutrient intake, and assess the seasonal nutritional constraints on the study population in west-central Alberta, Canada. The models examined the proportion of macronutrients that bears could consume by mixing their diet from food available in each season, and assessed the extent to which bears could consume the ratio of protein to non-protein energy previously demonstrated using captive bears to optimize mass gain. We found that non-selective feeding on ungulate carcasses provided a non-optimal macronutrient balance with surplus protein relative to fat and carbohydrate, reflecting adaptation to an omnivorous lifestyle, and that optimization through feeding selectively on different tissues of ungulate carcasses is unlikely. Bears were, however, able to dilute protein intake to an optimal ratio by mixing their otherwise high-protein diet with carbohydrate-rich fruit. Some individual food items were close to optimally balanced in protein to non-protein energy (e.g. Hedysarum alpinum roots), which may help explain their dietary prevalence. Ants may be consumed particularly as a source of lipids. Overall, our analysis showed that most food available to bears in the study area were high in protein relative to lipid or carbohydrate, suggesting the lack of non-protein energy limits the fitness (e.g. body size and reproduction) and population density of grizzly bears in this ecosystem.     

Nutritional Ecology of <Emphasis Type="Italic">Ateles chamek</Emphasis> in lowland Bolivia: How Macronutrient Balancing Influences Food Choices

All free-living animals must make choices regarding which foods to eat, with the choices influencing their health and fitness. An important goal in nutritional ecology is therefore to understand what governs animals’ diet selection. Despite large variation in the availability of different food items, Peruvian spider monkeys (Ateles chamek) maintain a relatively stable daily protein intake, but allow total energy intake to vary as a function of the composition of available food items. This is referred to as protein-dominated macronutrient balancing. Here we assess the influence of this nutritional strategy on daily and seasonal nutritional intakes, estimate the nutritional value of different foods, and interpret unusual food choices. We conducted continuous all-day observations of focal spider monkeys inhabiting a semideciduous forest in Bolivia. We recorded feeding events, collected foods, and analyzed their nutrient content. By using the Geometric Framework for nutrition, we show that individuals reached their daily end-point in nutrient space —balance between protein and nonprotein energy intake— by consuming nutritionally balanced foods or by alternating between nutritionally complementary foods. The macronutritionally balanced figs of Ficus boliviana were their primary staple food and therefore dominated their overall nutritional intake. Our results also demonstrate that spider monkeys consumed a diverse array of ripe fruits to overcome periods of fig scarcity rather than vice versa; they could obtain sufficient protein on a diet of pure fruit; and unripe figs constituted a nutritionally rewarding and reliable food resource. We hope that the approaches taken and the conclusions reached in this study will catalyze further inquiries into the nutritional ecology of frugivorous primates.     

The role of non-natural foods in the nutritional strategies of monkeys in a human-modified mosaic landscape

Many tropical animals inhabit mosaic landscapes including human-modified habitat. In such landscapes, animals commonly adjust feeding behavior, and may incorporate non-natural foods. These behavioral shifts can influence consumers' nutritional states, with implications for population persistence. However, few studies have addressed the nutritional role of non-natural food. We examined nutritional ecology of wild blue monkeys to understand how dietary habits related to non-natural foods might support population persistence in a mosaic landscape. We documented prevalence and nutritional composition of non-natural foods in monkey diets to assess how habitat use influenced their consumption, and their contribution to nutritional strategies. While most energy and macronutrients came from natural foods, subjects focused non-natural feeding activity on five exotic plants, and averaged about a third of daily calories from non-natural foods. Most non-natural food calories came from non-structural carbohydrates and least from protein. Consumption of non-natural foods related to time in human-modified habitats, which two groups used non-randomly. Non-natural and natural foods were similar in nutrients, and the amount of non-natural food consumed drove variation in nutritional strategy. When more daily calories came from non-natural foods, females consumed a higher ratio of non-protein energy to protein (NPE:P). Females also prioritized protein while allowing NPE:P to vary, increasing NPE while capitalizing on non-natural foods. Overall, these tropical mammals achieved a similar nutrient balance regardless of their intake of non-natural foods. Forest and forest-adjacent areas with non-natural vegetation may provide adequate nutrient access for consumers, and thus contribute to wildlife conservation in mosaic tropical landscapes.     

Dietary generalists and nutritional specialists: Feeding strategies of adult female blue monkeys (Cercopithecus mitis) in the Kakamega Forest,Kenya

Generalist primates eat many food types and shift their diet with changes in food availability. Variation in foods eaten may not, however, match variation in nutrient intake. We examined dietary variation in a generalist‐feeder, the blue monkey (Cercopithecus mitis), to see how dietary food intake related to variation in available food and nutrient intake. We used 371 all‐day focal follows from 24 adult females (three groups) in a wild rainforest population to quantify daily diet over 9 months. We measured food availability using vegetation surveys and phenology monitoring. We analyzed >700 food and fecal samples for macronutrient content. Subjects included 445 food items (species‐specific plant parts and insect morphotypes) in their diet. Variation in fruit consumption (percentage of diet and total kcal) tracked variation in availability, suggesting fruit was a preferred food type. Fruits also constituted the majority of the diet (by calories) and some fruit species were eaten more than expected based on relative availability. In contrast, few species of young leaves were eaten more than expected. Also, subjects ate fewer young leaves (based on calories consumed) when fruit or young leaves were more available, suggesting that young leaves served as fallback foods. Despite the broad range of foods in the diet, group differences in fiber digestibility, and variation that reflected food availability, subjects and groups converged on similar nutrient intakes (grand mean ± SD: 637.1 ± 104.7 kcal overall energy intake, 293.3 ± 46.9 kcal nonstructural carbohydrate, 147.8 ± 72.4 kcal lipid, 107.8 ± 12.9 kcal available protein, and 88.1 ± 17.5 kcal structural carbohydrate; N = 24 subjects). Thus, blue monkeys appear to be food composition generalists and nutrient intake specialists, using flexible feeding strategies to regulate nutrient intake. Findings highlight the importance of simultaneously examining dietary composition at both levels of foods and nutrients to understand primate feeding ecology.     

Introduction of Daytime Feeding in Rats by Exposure to Choice of a Sugar Diet

Food intakes of rats having first access to either sucrose or fructose as the carbohydrate source in a three-way selection of macronutrients were compared. In the first period of choice between sugar, protein and fat similar day/night intakes were found in rats given sucrose or fructose. When rats had a first experience with either sucrose or fructose as the carbohydrate source, their total energy and macronutrient intakes decreased dramatically and diurnal rather than nocturnal feeding occurred when sugar was switched. These findings indicate that a previous adaptation to a sugar as a carbohydrate source in a three-way selection design has long-lasting effects on the subsequent pattern and amount of food intake on a similar choice among diets.     

Introduction of Daytime Feeding in Rats by Exposure to Choice of a Sugar Diet

Food intakes of rats having first access to either sucrose or fructose as the carbohydrate source in a three-way selection of macronutrients were compared. In the first period of choice between sugar, protein and fat similar day/night intakes were found in rats given sucrose or fructose. When rats had a first experience with either sucrose or fructose as the carbohydrate source, their total energy and macronutrient intakes decreased dramatically and diurnal rather than nocturnal feeding occurred when sugar was switched. These findings indicate that a previous adaptation to a sugar as a carbohydrate source in a three-way selection design has long-lasting effects on the subsequent pattern and amount of food intake on a similar choice among diets.     

Testing protein leverage in lean humans: a randomised controlled experimental study

A significant contributor to the rising rates of human obesity is an increase in energy intake. The ‘protein leverage hypothesis’ proposes that a dominant appetite for protein in conjunction with a decline in the ratio of protein to fat and carbohydrate in the diet drives excess energy intake and could therefore promote the development of obesity. Our aim was to test the ‘protein leverage hypothesis’ in lean humans by disguising the macronutrient composition of foods offered to subjects under ad libitum feeding conditions. Energy intakes and hunger ratings were measured for 22 lean subjects studied over three 4-day periods of in-house dietary manipulation. Subjects were restricted to fixed menus in random order comprising 28 foods designed to be similar in palatability, availability, variety and sensory quality and providing 10%, 15% or 25% energy as protein. Nutrient and energy intake was calculated as the product of the amount of each food eaten and its composition. Lowering the percent protein of the diet from 15% to 10% resulted in higher (+12±4.5%, p = 0.02) total energy intake, predominantly from savoury-flavoured foods available between meals. This increased energy intake was not sufficient to maintain protein intake constant, indicating that protein leverage is incomplete. Urinary urea on the 10% and 15% protein diets did not differ statistically, nor did they differ from habitual values prior to the study. In contrast, increasing protein from 15% to 25% did not alter energy intake. On the fourth day of the trial, however, there was a greater increase in the hunger score between 1–2 h after the 10% protein breakfast versus the 25% protein breakfast (1.6±0.4 vs 25%: 0.5±0.3, p = 0.005). In our study population a change in the nutritional environment that dilutes dietary protein with carbohydrate and fat promotes overconsumption, enhancing the risk for potential weight gain.     

The effects of nutritional imbalance on compensatory feeding for cellulose-mediated dietary dilution in a generalist caterpillar

Abstract. The interactive effects of macronutrient balance [protein (P) : carbohydrate (C) ratio] and dietary dilution by cellulose on nutritional regulation and performance were investigated in the generalist caterpillar Spodoptera littoralis (Boisduval). Caterpillars were reared through the final stadium on one of 20 foods varying factorially in macronutrient content (P + C%: 42, 33.6. 25.2 or 16.8%) and P : C ratio (5 : 1, 2 : 1, 1 : 1, 1 : 2 or 1 : 5). The animals compensate by eating more of diluted foods, but suffer reduced nutrient intake in proportion to the degree of dilution. Increase in food intake with dilution is greater on balanced than imbalanced foods and this is reflected in greater reduction of dry pupal mass with dilution in the latter. Whereas dilution results in a reduction in the amount of whichever macronutrient is in excess in the food, by contrast, the ability to compensate for the deficient macronutrient in the food is unaffected by nutrient imbalance. Excess protein intake due to nutritional imbalance (diets with high P : C ratios) results in a regulatory decrease in the efficiency of retention of ingested nitrogen relative to restricted protein intake on oppositely imbalanced foods (low P : C ratios). By contrast, decreased protein intake due to dietary dilution is associated with a non‐regulatory reduction in the efficiency of retention, irrespective of P : C ratio. Dilution is similarly associated with reduced utilization efficiency of ingested carbohydrate. The ecological implications of these results are discussed.     

Nutritional Characteristics of Wild and Cultivated Foods for Chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) in Agricultural Landscapes

Primate habitats are being transformed by human activities such as agriculture. Many wild primates include cultivated foods (crops) in their diets, calling for an improved understanding of the costs and benefits of crop feeding. We measured the macronutrient and antifeedant content of 44 wild and 21 crop foods eaten by chimpanzees (Pan troglodytes schweinfurthii) in a mosaic habitat at Bulindi, Uganda, to evaluate the common assertion that crops offer high nutritional returns compared to wild forage for primates. In addition, we analyzed 13 crops not eaten at Bulindi but that are consumed by chimpanzees elsewhere to assess whether nutritional aspects explain why chimpanzees in Bulindi ignored them. Our analysis of their wild plant diet (fruit, leaves, and pith) corresponds with previous chemical analyses of primate plant foods. Compared to wild food equivalents, crops eaten by the chimpanzees contained higher levels of digestible carbohydrates (mainly sugars) coupled with lower amounts of insoluble fiber and antifeedants. Cultivated fruits were relatively nutritious throughout the ripening process. Our data support the assumption that eating cultivated foods confers energetic advantages for primates, although crops in our sample were low in protein and lipids compared to some wild foods. We found little evidence that crops ignored by the chimpanzees were less nutritious than those that they did eat. Nonnutritional factors, e.g., similarity to wild foods, probably also influence crop selection. Whether cultivated habitats can support threatened but flexible primates such as chimpanzees in the long term hinges on local people’s willingness to share their landscape and resources with them.     

Influence of Dry Season and Food Quality and Quantity on Behavior and Feeding Strategy of Propithecus verreauxi in Kirindy, Madagascar

According to optimal foraging theory, herbivores can base food choice mainly on the quality or the quantity of food, or both. Among herbivorous primates, folivorous lemurs living in the highly seasonal environment of Madagascar have to cope with the shortage of high-quality food during the dry season, at least in deciduous forests. We studied (Verreaux's sifaka) in Kirindy, western Madagascar, to understand the influence of dry season and food quality and quantity on behavioral patterns and feeding strategy (qualitative vs. quantitative dietary choice) of a folivorous lemur in a deciduous forest. We followed 7 groups (4 groups/period; 3 individuals/group/month) during 4 periods of the year (wet season: February–March; early/middle/late dry season: May–June; July–September; October–November). We collected samples of plants eaten and examined behavioral and feeding patterns, considering food quality (macronutrients, proteins/fibers ratio, and tannins) and abundance. We found 1) a significant reduction of home range, core area, and daily path length from the wet to the dry season, possibly related to dietary change and 2) a daily period of inactivity in the dry season for energy conservation. Regarding the feeding strategy, Kirindy sifakas showed 1) high variation and selection in choosing food items and 2) a dietary choice based mainly on quality: Kirindy sifakas fed on plant species/families independently from their abundance and tannins represented a feeding deterrent during the dry season. Overall, behavioral and dietary adaptations allow Kirindy sifakas to overcome the shortage of high-quality food in the lean period.     

Development of a culturally sensitive food frequency questionnaire for use in the Southern Community Cohort Study.

A food frequency questionnaire (FFQ) was developed to assess long-term habitual dietary intake in a cohort of approximately 100,000 40 to 79 year-old men and women living in the Southeastern US. Using the NHANES-III database for the southem region for specific race and sex subgroups, a list of 262 food categories was developed, coded and reduced to 102 food items that could discriminate between racial groups and account for large portions of cancer-relevant nutrients. The developed FFQ was tested in a pilot study in three southeastern states involving 239 African Americans and Whites, aged 56.9 +/- 12.2 years. The frequencies of consumption and portion sizes of the 102 foods were determined and intakes of various nutrients were estimated and compared with the NHANES-III data. African Americans reported higher total energy intakes and higher consumption of macronutrients and several micronutrients, compared to Whites. Estimated nutrient indices were higher among pilot study than among NHANES-III participants, although adjustment for total energy essentially eliminated the differences. Analysis of the frequency distribution of individual foods shows that the questionnaire includes commonly eaten foods that can discriminate between African Americans and Whites. The FFQ is currently being calibrated within the cohort study population.     

Balancing of lipid,protein, and carbohydrate intake in a predatory beetle following hibernation,and consequences for lipid restoration

Carnivorous animals are known to balance their consumption of lipid and protein, and recent studies indicate that some mammalian carnivores also regulate their intake of carbohydrate. We investigated macronutrient balancing and lipid restoration following hibernation in the ground beetle Anchomenus dorsalis, hypothesizing that carbohydrates might be important energy sources upon hibernation when predator lipid stores are exhausted and prey are equally lean. We recorded the consumption of lipid, protein, and carbohydrate over nine days following hibernation, as the beetles foraged to refill their lipid stores. Each beetle was given the opportunity to regulate consumption from two semi-artificial foods differing in the proportion of two of the three macronutrients, while the third macronutrient was kept constant. When analyzing consumption of the three macronutrients on an energetic basis, it became apparent that the beetles regulated lipid and carbohydrate energy interchangeably and balanced the combined energy intake from the two macronutrients against protein intake. Restoration of lipid stores was independent of the availability of any specific macronutrient. However, the energetic consumption required to refill lipid stores was higher when a low proportion of lipids was ingested, suggesting that lipids were readily converted into lipid stores while there were energetic costs associated with converting carbohydrate and protein into stored lipids. Our experiment demonstrates that carbohydrates are consumed and regulated as a non-protein energy source by A. dorsalis despite an expectedly low occurrence of carbohydrates in their natural diet. Perhaps carbohydrates are in fact an overlooked supplementary energy source in the diet of carnivorous arthropods.     

Patterns of frugivory of the Budongo Forest chimpanzees, Uganda

Frugivory patterns of the chimpanzees in the Budongo Forest Reserve, Uganda were studied between June 2000 and August 2001. Chimpanzee feeding habitats, movement, group size and food eaten were assessed using focal and scan sampling. It was found that fruits were scarce during the dry season, when chimpanzees appeared and moved in large groups over long distances and raided farms at the forest edge. Chimpanzee movement out of the forest to forage was influenced by seasonal fluctuations in availability of preferred foods as some cultivated crops are perennial. Presence of chimpanzees in a specific feeding habitat was related to the availability of edible fruits both within and between months, suggesting that the presence of food may influence chimpanzee movement patterns. Therefore, a good understanding of patterns of frugivory is essential for making informed decisions about conservation of chimpanzees and other frugivores like birds and monkeys in Budongo as different forest habitats are under varying human pressure because of logging and other forms of utilization.     

Baboon diet: a five-year study of stability and variability in the plant feeding and habitat of the yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania

The habitat and plant feeding of 64 well-habituated, individually identified adult male and female yellow baboons was studied for 5 years at Mikumi National Park, Tanzania. Variation across the years showed that a study of only one or two years would have been incomplete and misleading. The list of baboon food species obtained from Mikumi is considerably larger and more diverse than any previously reported. One to six plant parts were eaten from each of more than 180 species. The 25 most common tree genera all contained species used for food. Of the 50 most common grass, shrub and herb genera, 93% included plant foods. Using months in which a species was eaten during at least one year of the study, 21 staple species were eaten during a mean of 8.86 months and 7 were eaten in all 12 months. Although many foods were from commonly available plant species, 15 such species were only rarely eaten. The number of parts of a species eaten per month and an estimate of the amounts eaten per month both varied with temperature and rainfall, being lowest near the end of the cool, dry season. There were substantial differences from year to year in the timing and amount of food production of many species; nevertheless, the same broad feeding pattern was repeated in each of the 5 years of the study. Despite yearly variation in food availability, 14 or more staples and other common foods were eaten in any given month. If crops of many of these foods were to fail, a large number of less commonly eaten species could be substituted. Baboons are eclectic feeders that appear to be optimizing their diet by selective feeding from among a wide array of available foods in an ever-changing floristic environment.     

The nutritional consequences of foraging in primates: the relationship of nutrient intakes to nutrient requirements.

Many studies have examined the proportion of time that primates devote to feeding on various types of food, but relatively little is known about the intake rates associated with each food. However, the nutritional consequences of foraging can only be interpreted by comparing nutrient intakes with estimated nutrient requirements. The energy available to primates from ingested foods will depend both on the composition of the food and the extent to which various constituents, including fibre fractions, are digested. Both human and non-human primates have relatively low requirements for protein as a consequence of slow growth rates, small milk yields and relatively dilute milk. Because the nutrient demands of growth and reproduction are spread out over time, it appears that primates do not need to seek out foods of particularly high nutrient density, except perhaps during weaning. Although food selection in some species of primates appears to be correlated with the protein concentration of foods, it is unlikely that high dietary protein levels are required, at least when foods of balanced amino acid composition (such as leaves) are included in the diet.     

Macronutrient Self-Selection Pattern in Rats under Different Lighting Conditions

The effect of constant darkness (DD) and constant light (LL) on the circadian pattern of macronutrient self-selection, daily food intake and body weight was analysed in rats using an automated computer system. No significant differences in energy intake were observed between groups as regards energy intake or macronutrient preferences. Fat and CHO intakes showed a negative correlation (p &lt; 0.005 in LL and p &lt; 0.0005 in DD and LD), while protein intake remained constant, which suggests the existence of separate regulation mechanisms governing the intake of protein and energy. Energetic requirements can be preponderantly covered by CHO or fat, depending on the preferences of the animal. Body weight measurements reflected no significant variations between groups at the end of the experiment. However, the circadian pattern of wheel-running activity and the intake of the three macronutrients measured in both constant lighting conditions varied with respect to that observed in LD. This was particularly true in the case of LL, when constant illumination exerted a decoupling effect on the rhythms. The results indicate that lighting conditions modulate the circadian pattern of wheel-running activity and macronutrient intake. However, changes in temporal organisation of food intake did not affect macronutrient preferences, daily energy intake, number of meals, feeding duration or body weight, suggesting the existence of a double, circadian and homeostatic, control of such variables.