Energy Intake Rate Research Articles

Food Supply, Prey Selection and Estimated Consumption of Wintering Eurasian Curlews Feeding on Earthworms at Coastal Pastures

Coastal pastures provide supplementary foraging habitats for migratory shorebirds that rely on intertidal areas outside the breeding season. However, their role as foraging grounds for shorebirds is poorly understood. Here, we assessed the food supply, prey size selection, foraging behaviour and estimated consumption of a migratory shorebird, the near-threatened Eurasian Curlew Numenius arquata, at two temperate coastal pastures in northern Spain. Wintering Curlews only fed on earthworms (Oligochaeta), the main food available at coastal pastures. Average density and biomass were 102.3 ± 22.2 earthworms/m2 and 5.8 ± 1.3 g AFDW/m2, respectively, and only the density of surface living (i.e. epigeic) earthworms declined at the end of the winter. This food supply was comparatively high with respect to the biomass available in other man-made coastal habitats used by shorebirds wintering in temperate regions. Unexpectedly, the density of Curlews was higher at the pasture with the lowest food availability, though it declined significantly throughout the season at this site. Interestingly, Curlews preferentially selected the smallest size class (<32.5 mm) of epigeic earthworms, implying that a trade-off between energy intake rate and other fitness components could exist. Estimated consumption by Curlews was consistent with observed reductions in earthworm densities at both sites, thus reflecting a robust interaction between Curlews and epigeic earthworms at these agroecosystems throughout the non-breeding season. Our results highlight the potential role of earthworm communities at coastal pastures as food supply for declining migratory shorebirds.

The lunar cycle drives migration of a nocturnal bird.

Every year, billions of seasonal migrants connect continents by transporting nutrients, energy, and pathogens between distant communities and ecosystems. For animals that power their movements by endogenous energy stores, the daily energy intake rates strongly influence the speed of migration. If access to food resources varies cyclically over the season, migrants sensitive to changes in daily energy intake rates may adjust timing of migration accordingly. As an effect, individuals adjusting to a common temporal cycle are expected to approach synchrony in foraging and movement. A large-scale periodic pattern, such as the dark-light cycle of the moon, could thus synchronize migrations across animal populations. However, such cyclic effects on the temporal regulation of migration has not been considered. Here, we show the temporal influence of the lunar cycle on the movement activity and migration tactics in a visual hunting nocturnal insectivore and long-distance migrant, the European nightjar, Caprimulgus europeaus. We found that the daily foraging activity more than doubled during moonlit nights, likely driven by an increase in light-dependent fuelling opportunities. This resulted in a clear cyclicity also in the intensity of migratory movements, with occasionally up to 100% of the birds migrating simultaneously following periods of full moon. We conclude that cyclic influences on migrants can act as an important regulator of the progression of individuals and synchronize pulses of migratory populations, with possible downstream effects on associated communities and ecosystems.

Measure-valued solutions to size-structured population model of prey controlled by optimally foraging predator harvester

Radon-measure-valued solutions to a size structured population model of the McKendrick–von Foerster-type are analytically studied under general assumptions on individuals’ growth, birth and mortality rates. The model is used to describe changes in size structure of zooplankton when prey size-dependent mortality rate is a consequence of a planktivorous fish foraging in low prey-density environment (commonly found in predator-controlled populations). The model of foraging is based on the optimization of the rate of net energy intake as a function of predator speed. Mortality is defined as an operator on a metric space of nonnegative Radon measures equipped with the bounded Lipschitz distance. The solutions to the size structured model of zooplankton population are studied analytically and numerically. Numerical solutions (derived using the Escalator Boxcar Train (EBT)-like schema), in particular those starting from Dirac deltas corresponding to distinct cohorts, exhibit regularization in time and convergence to the same stationary state.

Putting mechanisms in foraging theory: the role of computational mechanisms in optimal decision making

Classic optimization models explain adaptive behaviours in terms of optimal cost–benefit trade-offs. They assume flexibility and make testable predictions about what animals should do in order to maximize their fitness. But they do not usually ask how animals can do it. Since flexible behaviours can be globally optimal but locally suboptimal, the optimality models should directly focus on the underlying mechanisms of behavioural flexibility, such as learning and decision making. In this paper, I use the classic ‘diet’ model of optimal foraging theory (OFT) to investigate the evolution of decision-making mechanisms at both the computational and the algorithmic level. At the computational level, I define benefits (the expected rate of net energy intake) and costs (lost opportunity) and formalize the decision rule. At the algorithmic level, I present two sequential sampling models, which differ in the way information is internally represented and used. The first model represents the prospective items along a one-dimensional scale of values (benefit–cost differences) and it uses a fixed amount of sensory information (and time) to make decisions. The second model represents items in the two-dimensional plane of benefits and costs, and it uses a variable amount of information. I test the models along a gradient of resource abundance. In each environment, I use OFT to classify resources as either profitable or unprofitable and describe the model performance in terms of decision time and accuracy. At high resource density, both models predict foraging choice to be more selective, but less accurate, than at low density, because decisions are strongly biased in the false-positive direction. At low resource density, the two-dimension model performs better than the one-dimension alternative, because it takes less time to make more accurate decisions. These differences, however, disappear when resources are abundant.

Effect of feeding frequency and sow parity based on isocaloric intake during gestation on sow performance.

The aim of this study was to investigate the effect of feeding frequency and sow parity based on same rate of maintenance energy intake during gestation on sow performance. One hundred and seventy-seven sows [Topigs Norsvin 70, Landrace × Large White, Topigs Norsvin USA, Burnsville, MN; parity 3.80 ± 0.16; initial BW = 211.34 ± 3.37 kg; backfat (BF) 13.57 ± 0.54 mm] were blocked by parity, balanced for BW, and randomly assigned to 1 of 3 treatments in a randomized complete block design. Treatments included sows fed corn-soybean meal-based diet 1× daily at 0730 h (control, T1), 2× daily [half ration at 0730 and 1530 h (T2)], or 3× daily [a third portion at 0730, 1130, and 1530 h (T3)], with daily feed quantity kept at 1.25 × maintenance energy intake [100 × (BW)0.75] kcal ME/d. Treatments were imposed from day 30 of gestation. Sows received on average 6,921, 7,129, and 7,399 kcal ME/d from days 30 to 60, days 61 to 90, days 91 to 109 of gestation, respectively. Feeding frequency during gestation had no effect on lactation ADFI (P > 0.10). Sows fed 3× daily during gestation had improved lactation G:F (P = 0.040) compared with sows fed 2× but similar to control sows (P = 0.338). Treatment did not alter BW or BW variations during gestation, lactation, or from days 30 to wean (P > 0.10). Sows fed 2× daily had tendency to gain BF from day 30 to day 109 of gestation (P = 0.053) but tended to lose BF during lactation (P = 0.091) relative to the control sows. Feeding frequency (2× and 3× daily) tended to increase the number of piglets weaned by 0.40 (P = 0.056) and 0.53 (P = 0.098) piglets, respectively, compared with control sows. Sows fed 2× daily during gestation had reduced number of stillborn relative to control sows (P = 0.035). From day 30 to wean, gilts had propensity to lose BF relative to P1+ (P = 0.094), but lost BF compared with P3+ and P6+ sows (P = 0.003). Parity P6+ sows had highest percentage of both 72 h and preweaning piglet mortality than P0, P1+, and P3+ sows (P < 0.05). In conclusion, parity (P6+) had greater lactation BW gain but higher mortalities relative to lower parity sows. Sows fed 2× daily tended to gain BF from days 30 to 109 of gestation and had reduced number of stillborn relative to control sows. It appears that increasing gestation sow feeding frequency from 1× daily to 2× and 3× daily may reduce the number of stillborn and increase litter size at weaning although most of the reproductive traits were not affected.

Optimal Time and Target for Evaluating Energy Delivery after Adjuvant Feeding with Small Bowel Enteral Nutrition in Critically Ill Patients at High Nutrition Risk.

Small bowel enteral nutrition (SBEN) may improve nutrient delivery to critically ill patients intolerant of gastric enteral nutrition. However, the optimal time and target for evaluating SBEN efficacy are unknown. This retrospective cohort study investigates these parameters in 55 critically ill patients at high nutrition risk (modified NUTRIC score ≥ 5). Daily actual energy intake was recorded from 3 days before SBEN initiation until 7 days thereafter. The energy achievement rate (%) was calculated as follows: (actual energy intake/estimated energy requirement) × 100. The optimal time was determined from the day on which energy achievement rate reached >60% post-SBEN. Assessment results were as follows: median APACHE II score, 27; SOFA score, 10.0; modified NUTRIC score, 7; and median time point of SBEN initiation, ICU day 8. The feeding volume, energy and protein intake, and achievement rate (%) of energy and protein intake increased significantly after SBEN (p < 0.001). An energy achievement rate less than 65% 3 days after SBEN was significantly associated with increased mortality after adjusting for confounding factors (odds ratio, 4.97; 95% confidence interval, 1.44–17.07). SBEN improves energy delivery in critically ill patients who are still at high nutrition risk after 1 week of stomach enteral nutrition.

Leave or stay? Video-logger revealed foraging efficiency of humpback whales under temporal change in prey density.

Central place foraging theory (CPF) has been used to predict the optimal patch residence time for air-breathing marine predators in response to patch quality. Humpback whales (Megaptera novaeangliae) forage on densely aggregated prey, which may induce drastic change in prey density in a single feeding event. Thus, the decision whether to leave or stay after each feeding event in a single dive in response to this drastic change, should have a significant effect on prey exploitation efficiency. However, whether humpback whales show adaptive behavior in response to the diminishing prey density in a single dive has been technically difficult to test. Here, we studied the foraging behavior of humpback whales in response to change in prey density in a single dive and calculated the efficiency of each foraging dive using a model based on CPF approach. Using animal-borne accelerometers and video loggers attached to whales, foraging behavior and change in relative prey density in front of the whales were successfully quantified. Results showed diminishing rate of energy intake in consecutive feeding events, and humpback whales efficiently fed by bringing the rate of energy intake close to maximum in a single dive cycle. This video-based method also enabled us to detect the presence of other animals around the tagged whales, showing an interesting trend in behavioral changes where feeding duration was shorter when other animals were present. Our results have introduced a new potential to quantitatively investigate the effect of other animals on free-ranging top predators in the context of optimal foraging theory.

How important are different non-native conifers in Britain to Common Crossbills Loxia curvirostra curvirostra?

ABSTRACTCapsulePines physically defend their seeds against seed-eating birds and mammals more than spruces or larches. Cone characteristics reflect the rate at which Common Crossbills Loxia curvirostra curvirostra extract seeds from different non-native conifers in Britain.AimsTo assess the profitability of different non-native conifers in Britain for Common Crossbills in winter.MethodsWe measured cone and seed parameters of conifers (Norway Spruce Picea abies, Sitka Spruce Picea sitchensis, Lodgepole Pine Pinus contorta and Japanese Larch Larix kaempferi) introduced into Britain and compared these with the native Scots Pine Pinus sylvestris. Feeding trials with captive Common Crossbills assessed intake rates.ResultsThe pines had thick and long scales, Japanese Larch had thin, short scales but thick seed coats and Sitka Spruce had thin, papery and short scales, and the thinnest seed coat. The two spruce species had more seeds per cone and the kernels had a higher energy content than the pines and larch. Feeding trials, simulating cones in winter, found that Common Crossbills failed to access seeds in closed Scots Pine cones. They also had difficulty in prising the scales of closed Lodgepole Pine cones but were able to forage on partially open cones. They took longer to extract seeds from large, open Lodgepole Pine cones than small ones, reflecting the effect of increasing scale thickness in larger pine cones. They also took longer to extract Lodgepole Pine seeds than Sitka Spruce and larch seeds. Although Common Crossbills could extract seeds quickly from open Sitka Spruce cones, the small seed size made the energy intake rate similar to Japanese Larch, if all seeds contained a kernel. However, after accounting for the proportion of seeds with a kernel, Sitka Spruce was the more profitable.ConclusionThe conifer food resource for crossbills in Britain has changed through the planting of non-native conifers. The physical properties of the cones and seeding phenology influence the rate at which Common Crossbills can extract seeds.

A quick tongue: older honey bees dip nectar faster to compensate for mouthpart structure deterioration.

The western honey bee, Apis mellifera L. (Hymenoptera), is arguably the most important pollinator worldwide. While feeding, A. mellifera uses a rapid back-and-forth motion with its brush-like mouthparts to probe pools and films of nectar. Because of the physical forces experienced by the mouthparts during the feeding process, we hypothesized that the mouthparts acquire wear or damage over time, which is paradoxical, because it is the older worker bees that are tasked with foraging for nectar and pollen. Here, we show that the average length of the setae (brush-like structures) on the glossa decreases with honey bee age, particularly when feeding on high-viscosity sucrose solutions. The nectar intake rate, however, remains nearly constant regardless of age or setae length (0.39±0.03 μgs-1 for honey bees fed a 45% sucrose solution and 0.48±0.05 μgs-1 for those fed a 35% sucrose solution). Observations of the feeding process with high-speed video recording revealed that the older honey bees with shorter setae dip nectar at a higher frequency. We propose a liquid transport model to calculate the nectar intake rate, energy intake rate and the power to overcome viscous drag. Theoretical analysis indicates that A. mellifera with shorter glossal setae can compensate both nectar and energy intake rates by increasing dipping frequency. The altered feeding behavior provides insight into how A. mellifera, and perhaps other insects with similar feeding mechanisms, can maintain a consistent fluid uptake rate, despite having damaged mouthparts.

A new satellite-based indicator to identify spatiotemporal foraging areas for herbivorous waterfowl

The distribution of food resources is a key factor in habitat selection. Herbivorous waterfowl prefer early-stage growing plants (from the onset of plant growth to the peak in nutrient biomass) as these offer higher energy intake rates. This plant development stage is not fully captured by commonly used satellite-derived vegetation indicators, which focus on plant biomass (e.g., Enhanced Vegetation Index, EVI) or active plant growth (e.g., the differential EVI between current and a previous date, diffEVI). To improve mapping suitable grazing areas for herbivorous waterfowl, we propose a new satellite-based plant growth indicator of early-stage plant growth (ESPG). We hypothesize that herbivorous waterfowl prefer plants at an early development stage during the growing season and select plants with a relatively later end of ESPG during the non-growing season. We use satellite tracking data of 20 greater white-fronted geese (Anser albifrons) wintering in the Yangtze River floodplain to validate our predictions. We build generalized linear models for goose distributions during the growing and non-growing seasons and compare the performance of ESPG to commonly used plant growth indictors (EVI and diffEVI). During the growing season, ESPG can explain 53% of variation in the goose distribution, outperforming EVI (27%) and diffEVI (34%). During the non-growing season, only the end of ESPG significantly influences goose distribution, explaining 25% of the variance (ESPG: AUC = 0.78; EVI: AUC = 0.58; diffEVI: AUC = 0.58). The newly-developed plant growth indicator ESPG could be used to improve models of herbivorous waterfowl distributions and hence support efforts toward waterfowl conservation and wetland management.

Quadratic relationships between group size and foraging efficiency in a herbivorous primate

The effect of feeding competition on foraging efficiency is an important link between ecological factors and the social organization of gregarious species. We examined the effects of group size on daily travel distances, activity budgets, and energy intake of mountain gorillas in Rwanda. We measured daily travel distances of five groups, activity budgets of 79 gorillas in nine groups, and energy intake data for 23 adult females in three groups over a 16-month period. Travel distances and the proportion of time spent traveling increased with size for most groups, which would be expected if their foraging efficiency is limited by intragroup feeding competition. However, travel distances and times decreased for the largest group, which also had higher energy intake rates than intermediate sized groups. The improved foraging efficiency of the largest group may be explained by advantages in intergroup contest competition. The largest group had much lower home range overlap than the other study groups which may be due to groups avoiding one another as a result of male mating competition. Collectively, our results indicate that intermediate sized groups had the lowest foraging efficiency and provide a new twist on the growing evidence of non-linear relationships between group size and foraging efficiency in primates.

The Potential Use of a Ketogenic Diet in Pancreatobiliary Cancer Patients After Pancreatectomy.

High-carbohydrate diets are generally provided to post-pancreatectomy cancer patients. Low energy density of this diet may obstruct proper energy intake and recovery. This study aimed to assess the effects of high-fat, high-energy ketogenic diet (KD) in these patients. After pancreatectomy, 9 patients were provided with general diet (GD) while 10 were served KD. Meal compliance, energy intake rate, meal satisfaction and presence of complications were monitored throughout hospital stay. Data on nutritional status, serum lipids and body composition were collected and compared between groups. Meal compliance, energy intake rate and meal satisfaction score were higher in KD. There were no differences in complications, nutritional status and serum lipids. The decrease in body cell mass (BCM) was greater in GD. Post-pancreatectomy cancer patients who consumed KD had a higher energy intake and BCM. These results suggest the potential use of KD as an adjuvant anti-cancer therapy.

Energetic Consequences for a Northern, Range-Edge Lizard Population

Lizards at the northern, cool edge of their geographic range in the northern hemisphere should encounter environmental conditions that differ from those living near the core of their range. To better understand how modest climate differences affect lizard energetics, we compared daily feeding and metabolism rates of individual Sceloporus occidentalis in two populations during mid-summer. Chuckanut Beach (CB) was a cool, maritime climate in northern Washington State, and Sondino Ranch (SR) was a warmer, drier climate in southern, inland Washington. We found no difference between populations in daily energy expenditure (DEE), as calculated from doubly labeled water estimates. The CB population, however, had significantly higher prey availability and rate of daily energy intake (DEI) as estimated from fecal pellet masses. Consequently, CB lizards had higher size-adjusted body masses than lizards from SR. Within CB, during midsummer, DEE was similar to DEI. Within the SR population, DEE trended higher than DE...

EXPANDING THE ARENA OF SPORT NUTRITION

Apply It! A sports RDN can help active individuals of all levels and abilities achieve their performance and/or health goals. At the end of this article, you should be able to apply your knowledge to: Consider referring patients or clients who work in physically demanding professions or environments to a sports RDN even if they aren’t “traditional” athletes. Look for an RDN who has the Certified Specialist in Sports Dietetics (CSSD) credential. Summary Statement Outside of collegiate and professional athletics, the expertise of the sports RDN is highly underused. Find out how sports RDNs working with less traditional athlete populations have found their niche and are expanding the arena of sport nutrition practice. Pulled Text Among different styles of dance, ballet dancers tend to be the leanest and have the lowest body fat percentages (6,7). They generally have low energy intake (70%–80% of recommended) and high rates of eating disorders (EDs) or disordered eating behaviors. It is estimated that their risk for developing an ED is three times that of nondancers (8). The most common manifestations of low energy availability that Moretti encounters in her practice are menstrual irregularities, iron deficiency, gastrointestinal issues, and bone stress injuries. She explains that, “dancers are aesthetic athletes, which means there is a delicate balance between maintaining a strong body and supporting the aesthetic ideals of the profession. My role is to help these dancers achieve both.” “High schools are an untapped opportunity to provide and support both the development of good eating habits for performance but also for lifelong health and wellness. The reality is that only 6% to 8% of high school athletes will continue with their sport in college, and providing education to this group will hopefully set them on a path to become healthier and understand the role food has on their body, not just for performance but when sports end.”

Discrete, high-latitude foraging areas are important to energy budgets and population dynamics of migratory leatherback turtles

Many broadly distributed migratory species exhibit fidelity to fine-scale areas that support vital life history requirements (e.g., resource acquisition, reproduction). Thus, such areas are critical for population dynamics and are of high conservation priority. Leatherback sea turtles are among the world’s most widely distributed species, and their breeding and feeding areas are typically separated by thousands of kilometres. In this study, we analysed turtle-borne video data on daytime feeding rates and energy acquisition in Nova Scotia, Canada, to quantify the importance of this discrete, seasonal foraging area for leatherback energy requirements. Based on daytime foraging only, we estimate that a single foraging season in Nova Scotia could support 59% of a non-breeding leatherback’s annual energy budget, and 29% of energetic requirements for a female on a typical 2-year reproductive cycle. However, maximum energy intake rates for leatherbacks are nearly four times lower than those of mammals and birds due the low energy content of leatherbacks’ gelatinous zooplankton prey. These results illustrate that high quality, local-scale foraging areas such as Nova Scotia are critically important to the stability and future growth of the leatherback population in the Northwest Atlantic Ocean. Thus, as with other migratory species, efforts to reduce threats and maintain habitat quality in such areas should be high conservation priorities.

Genotype by feed interaction for feed efficiency and growth performance traits in pigs.

A major objective of pork producers is to reduce production cost. Feeding may account for over 75% of pork production costs. Thus, selecting pigs for feed efficiency (FE) traits is a priority in pig breeding programs. While in the Americas, pigs are typically fed high-input diets, based on corn and soybean meal (CS); in Western Europe, pigs are commonly fed diets based on wheat and barley with high amounts of added protein-rich coproducts (WB), e.g., from milling and seed-oil industries. These two feeding scenarios provided a realistic setting for investigating a specific type of genotype by environment interaction; thus, we investigated the genotype by feed interaction (GxF). In the presence of a GxF, different feed compositions should be considered when selecting for FE. This study aimed to 1) verify the presence of a GxF for FE and growth performance traits in different growth phases (starter, grower, and finisher) of 3-way crossbred growing-finishing pigs fed either a CS (547 boars and 558 gilts) or WB (567 boars and 558 gilts) diet; and 2) to assess and compare the expected responses to direct selection under the 2 diets and the expected correlated responses for one diet to indirect selection under the other diet. We found that GxF did not interfere in the ranking of genotypes under both diets for growth, protein deposition, feed intake, energy intake, or feed conversion rate. Therefore, for these traits, we recommend changing the diet of growing-finishing pigs from high-input feed (i.e., CS) to feed with less valuable ingredients, as WB, to reduce production costs and the environmental impact, regardless of which diet is used in selection. We found that GxF interfered in the ranking of genotypes and caused heterogeneity of genetic variance under both diets for lipid deposition (LD), residual energy intake (REI), and residual feed intake (RFI). Thus, selecting pigs under a diet different from the diet used for growing-finishing performance could compromise the LD in all growth phases, compromise the REI and RFI during the starter phase, and severely compromise the REI during the grower phase. In particular, when pigs are required to consume a WB diet for growing-finishing performance, pigs should be selected for FE under the same diet. Breeding pigs for FE under lower-input diets should be considered, because FE traits will become more important and lower-input diets will become more widespread in the near future.

Metabolic Scope as a Proximate Constraint on Individual Behavioral Variation: Effects on Personality, Plasticity, and Predictability.

Behavioral ecologists have hypothesized that among-individual differences in resting metabolic rate (RMR) may predict consistent individual differences in mean values for costly behaviors or for behaviors that affect energy intake rate. This hypothesis has empirical support and presently attracts considerable attention, but, notably, it does not provide predictions for individual differences in (a) behavioral plasticity or (b) unexplained variation (residual variation from mean individual behavior, here termed predictability). We outline how consideration of aerobic maximum metabolic rate (MMR) and particularly aerobic scope (= MMR - RMR) can be used to simultaneously make predictions about mean and among- and within-individual variation in behavior. We predict that while RMR should be proportional to an individual's mean level of sustained behavioral activity (one aspect of its personality), individuals with greater aerobic scope will also have greater scope to express behavioral plasticity and/or greater unpredictability in behavior (=greater residual variation). As a first step toward testing these predictions, we analyze existing activity data from selectively bred lines of mice that differ in both daily activity and aerobic scope. We find that replicate high-scope mice are more active on average and show greater among-individual variation in activity, greater among-individual variation in plasticity, and greater unpredictability. These data provide some tentative first support for our hypothesis, suggesting that further research on this topic would be valuable.

Early-life begging effort reduces adult body mass but strengthens behavioural defence of the rate of energy intake in European starlings.

Animals require strategies for coping with periods when food is scarce. Such strategies include storing fat as a buffer, and defending the rate of energy intake by changing foraging behaviour when food becomes difficult to obtain. Storage and behavioural defence may constitute alternative strategies for solving the same problem. We would thus expect any developmental influences that limit fat storage in adulthood to also induce a compensatory alteration in adult foraging behaviour, specifically when food is hard to obtain. In a cohort of hand-reared European starlings, we found that higher manipulated early-life begging effort caused individuals to maintain consistently lower adult body mass over a period of two years. Using an operant foraging task in which we systematically varied the costs of obtaining food, we show that higher early-life begging effort also caused stronger behavioural defence of the rate of energy intake when food was more costly to obtain. Among individuals with the same developmental history, however, those individuals who defended their rate of energy intake most strongly were also the heaviest. Our results are relevant to understanding why there are marked differences in body weight and foraging behaviour even among individuals inhabiting the same environment.

Study of the interactive effect of prey toxin and optimal foraging strategy on a predator–prey model

The optimal foraging theory predicts that predators choose prey with more net rate of energy intake and less energy costs if there are multiple food sources available. Toxins are found in many species in nature. Those toxins may be produced by prey as self-protection from predatory animals, or come from other sources such as pesticide residue. Therefore, it requires a balance between energy intake and toxicity damage. In order to study the interactive effect of prey toxin and optimal foraging strategy, we construct a predator–prey model with toxin-induced functional response and optimal foraging property. Dynamical analysis shows that the optimal strategy system presents more complex dynamical behavior than the fixed preference system. We conclude that optimal foraging strategy might play a key role in stabilizing or destabilizing the coexistence states of the species in the system, depending on the level of prey toxins.

Diet and Anthropometrics of Children With Inflammatory Bowel Disease: A Comparison With the General Population

There is a lack of knowledge regarding the diet of children with inflammatory bowel disease (IBD). Therefore, we investigated dietary intake in pediatric IBD compared to the general population and assessed anthropometrics and food avoidance. In this cross-sectional cohort study, patients younger than 18 years with IBD were included (2014-2017). Dietary intake (total energy, macro nutrients, food types) was assessed using a Food Frequency Questionnaire (FFQ) and compared with a matched reference population (n = 306). There were 102 patients included (55% male, median age 15.0 years). Median height Z-score was -0.39 (interquartile range [IQR]: -1.17 to 0.26). Growth failure (height Z-scores<-1.64) was present in 11% of patients. Median BMI Z-score was 0.36 (IQR: -0.70 to 0.96). Acute malnutrition (weight-for-height Z-score<-2) was present in 3% of patients. Energy intake was lower in pediatric IBD compared to the reference population (mean kilojoule/day: 8286 vs 9794, P < 0.001). Protein intake did not differ, while fat intake was higher in pediatric IBD (mean gram/day: 101 vs 91, P < 0.001), with higher intake of vegetable oils/fats. Carbohydrate intake was lower in pediatric IBD (mean gram/day: 267 vs 305, P < 0.001), with lower intake of food types high in sugar. Food avoidance was reported in 53% of patients, with frequent avoidance of spicy (46%), high-fat food (30%), and dairy (30%). The diet of children with IBD differs from the general pediatric population, with lower energy intake and high rates of food avoidance. Evaluation of the dietary intake alongside anthropometrics may be important to prevent nutrition deficiencies and promote health.