New insights in insect prey choice by chimpanzees and gorillas in southeast Cameroon: the role of nutritional value

The insect diet of chimpanzees and gorillas living at the northern periphery of the Dja Biosphere Reserve in southeast Cameroon and its nutritional contribution is described. We analyzed fecal samples and recorded additional evidence of insectivory. A detailed prey species list is presented for both apes. We carried out nutritional analyses (macronutrients, macro- and micro-minerals) on 11 important and eight nonimportant, but accessible, ant and termite prey species, and estimated the average nutrient intake/day through insects. Although gorillas ate insects more frequently, the average prey biomass intake/day by chimpanzees was twice that by gorillas. The lack of tool-use by gorillas cannot be the main reason for the small overlap of important prey species. Both apes did not seem to consume ant prey for one or more specific nutrients. Also other factors, such as medicinal use, should be considered. Termites, on the other hand, seemed to be selected for particular nutrients. Gorilla intake of the important termite prey, Cubitermes and Thoracotermes, met with estimated iron requirements. Their potential role as antidiarrheal treatment is as yet unclear. Chimpanzee intake of the important termite prey, Macrotermes spp., met with estimated manganese requirements and the protein intake/day (mean: 2 g/d) reached significant values (>20 g/d). To fully understand the importance of nutritional contributions of insects to ape diets in Cameroon, the chemical composition and nutrient intake of fruit and foliage in their diets should be investigated.     

Environmental effects on nutrient and energy metabolism in pigs

Besides the genetic predisposition and the dietary supply of nutrients, environmental factors affect the performance of the pig. Environment can affect the nutrient composition and availability of the feed. It can also influence appetite and therefore the feed intake. Furthermore, nutrient and energy utilization on the level of digestion and intermediate metabolism can depend on environmental factors. Especially the energy requirements of the pig are determined by such factors like physical activity or climate. Finally, stress or disease are interacting with the environment, nutrient and energy utilization as well as performance of the pigs.     

Uncovering the Nutritional Landscape of Food

Recent progresses in data-driven analysis methods, including network-based approaches, are revolutionizing many classical disciplines. These techniques can also be applied to food and nutrition, which must be studied to design healthy diets. Using nutritional information from over 1,000 raw foods, we systematically evaluated the nutrient composition of each food in regards to satisfying daily nutritional requirements. The nutrient balance of a food was quantified and termed nutritional fitness; this measure was based on the food’s frequency of occurrence in nutritionally adequate food combinations. Nutritional fitness offers a way to prioritize recommendable foods within a global network of foods, in which foods are connected based on the similarities of their nutrient compositions. We identified a number of key nutrients, such as choline and α-linolenic acid, whose levels in foods can critically affect the nutritional fitness of the foods. Analogously, pairs of nutrients can have the same effect. In fact, two nutrients can synergistically affect the nutritional fitness, although the individual nutrients alone may not have an impact. This result, involving the tendency among nutrients to exhibit correlations in their abundances across foods, implies a hidden layer of complexity when exploring for foods whose balance of nutrients within pairs holistically helps meet nutritional requirements. Interestingly, foods with high nutritional fitness successfully maintain this nutrient balance. This effect expands our scope to a diverse repertoire of nutrient-nutrient correlations, which are integrated under a common network framework that yields unexpected yet coherent associations between nutrients. Our nutrient-profiling approach combined with a network-based analysis provides a more unbiased, global view of the relationships between foods and nutrients, and can be extended towards nutritional policies, food marketing, and personalized nutrition.     

Der schmale Grat zwischen Prävention und Placebo: Nahrungsergänzungsmittel

Consumers expect vitamin and mineral supplements to protect them against diseases. In Germany the legal basis of food supplements is the national food law, therefore any advertising regarding diseases is forbidden. Since there exist no definition and no legal basis for the product group by now, there are many products with illegal advertisement and without any health effect in the market. Furthermore the differentiation from other product categories, especially drugs, is difficult. Food supplements can help to meet the needs for critical nutrients and are able to ameliorate the supply of health protecting substances. This is especially important for risk groups with higher nutrient requirements or low energy intake. The bioavailability of substances from supplements is mostly better than from food. Therefore dosages should correspond to those taken by normal food consumption. It is the pragmatic way to use food supplements in order to prevent inadequate nutrient intake especially in risk groups.     

Little evidence for intralocus sexual conflict over the optimal intake of nutrients for life span and reproduction in the black field cricket Teleogryllus commodus

There is often large divergence in the effects of key nutrients on life span (LS) and reproduction in the sexes, yet nutrient intake is regulated in the same way in males and females given dietary choice. This suggests that the sexes are constrained from feeding to their sex‐specific nutritional optima for these traits. Here, we examine the potential for intralocus sexual conflict (IASC) over optimal protein and carbohydrate intake for LS and reproduction to constrain the evolution of sex‐specific nutrient regulation in the field cricket, Teleogryllus commodus. We show clear sex differences in the effects of protein and carbohydrate intake on LS and reproduction and strong positive genetic correlations between the sexes for the regulated intake of these nutrients. However, the between‐sex additive genetic covariance matrix had very little effect on the predicted evolutionary response of nutrient regulation in the sexes. Thus, IASC appears unlikely to act as an evolutionary constraint on sex‐specific nutrient regulation in T. commodus. This finding is supported by clear sexual dimorphism in the regulated intake of these nutrients under dietary choice. However, nutrient regulation did not coincide with the nutritional optima for LS or reproduction in either sex, suggesting that IASC is not completely resolved in T. commodus.     

Balancing nutrient supply and nutrient requirements in grazing sheep

Attempting to achieve a balance between the supply of and requirements for the major nutrients implies that demands for major nutrients can be adequately quantified, that the nutritive value of the consumed diet can be described in similar terms and that the diet actually consumed by the grazing sheep can be estimated, or at least predicted, from pasture and animal conditions. Several systems exist for defining the nutrient requirements of sheep and, whilst there are real differences between them, all are sufficiently accurate to allow their use in ration formulation and in grazing animal management. Similarly, nutritive value of feed components can be defined accurately. In grazing sheep, the major difficulty in balancing the supply of consumed nutrients against nutrient requirements is the estimation of diet composition and intake. Computer-based decision support tools are a useful aid to overcoming this problem. It is suggested that since profit derives from animal production per hectare and not per animal, the balancing of nutrient supply and requirements should not be attempted on an individual-animal basis.     

Bumble bees selectively use native and exotic species to maintain nutritional intake across highly variable and invaded local floral resource pools

1. Changes to plant community composition after invasion are well documented but how these shifts directly affect higher trophic levels is still poorly understood. One potentially important factor is the change in nutritional availability after an invasion. Shifts in nutrient availability could affect the nutrient intake of organisms that live in invaded habitats, causing reduced fecundity and survival. 2. The effects of the interaction among nutrient availability, selection, and diet on nutrient intake of a native bumble bee were examined. No nutritional differences were found between exotic and native pollen or collected and non‐collected pollen in protein or amino acid content, suggesting that differences in nutrient intake from random are based on selection. 3. Nutrient intake was simulated when pollen was selected randomly across all available plant species and when selection was restricted to native plants only or exotic plants only using a permutation model and compared with observed collection. The results suggest that pollen collection is non‐random and that selecting only native or exotic plants cannot provide the protein or amino acid intake observed. 4. These results may help to explain why the responses of native bees to exotic plants are so variable. If the exotic plants in a community can supply the necessary nutrients, bees may readily incorporate them into their diets, but if not, exotic plants may be avoided.     

Sex‐specific effects of protein and carbohydrate intake on reproduction but not lifespan in Drosophila melanogaster

Modest dietary restriction extends lifespan (LS) in a diverse range of taxa and typically has a larger effect in females than males. Traditionally, this has been attributed to a stronger trade‐off between LS and reproduction in females than in males that is mediated by the intake of calories. Recent studies, however, suggest that it is the intake of specific nutrients that extends LS and mediates this trade‐off. Here, we used the geometric framework (GF) to examine the sex‐specific effects of protein (P) and carbohydrate (C) intake on LS and reproduction in Drosophila melanogaster. We found that LS was maximized at a high intake of C and a low intake of P in both sexes, whereas nutrient intake had divergent effects on reproduction. Male offspring production rate and LS were maximized at the same intake of nutrients, whereas female egg production rate was maximized at a high intake of diets with a P:C ratio of 1:2. This resulted in larger differences in nutrient‐dependent optima for LS and reproduction in females than in males, as well as an optimal intake of nutrients for lifetime reproduction that differed between the sexes. Under dietary choice, the sexes followed similar feeding trajectories regulated around a P:C ratio of 1:4. Consequently, neither sex reached their nutritional optimum for lifetime reproduction, suggesting intralocus sexual conflict over nutrient optimization. Our study shows clear sex differences in the nutritional requirements of reproduction in D. melanogaster and joins the growing list of studies challenging the role of caloric restriction in extending LS.     

Do Pollinators Contribute to Nutritional Health?

Despite suggestions that animal pollinators are crucial for human nutritional health, no studies have actually tested this claim. Here, we combined data on crop pollination requirements, food nutrient densities, and actual human diets to predict the effects of pollinator losses on the risk of nutrient deficiency. In four developing countries and across five nutrients, we found that 0 to 56% of populations would become newly at risk if pollinators were removed. Increases in risk were most pronounced for vitamin A in populations with moderate levels of total nutrient intake. Overall, the effects of pollinator decline varied widely among populations and nutrients. We conclude that the importance of pollinators to human nutrition depends critically on the composition of local diets, and cannot be reliably predicted from global commodity analyses. We identify conditions under which severe health effects of pollinator loss are most likely to occur.     

Effect of infection on nutritional status.

All infections no matter how mild decrease nutrient intakes and increase nutrient losses even when subclinical. The losses include decreased intestinal absorption, direct loss of nutrients in the gut, internal diversion for metabolic responses to infection and increased BMR when fever is present. Infection influences in this way not only protein and energy status but also that of most other nutrients. The clinical importance of these consequences of infection depends on the prior state of the individual, the nature and duration of the infection and the diet of the individual during the infection, particularly dietary intake during the convalescent period and whether full recovery takes place before another infection occurs. In industrialized countries particular attention must be paid to the nutrition of hospitalized patients since they are frequently debilitated by their primary disease, morbidity, and their nutritional status. Morbidity and mortality are increased by nosocomial infections to which the poorly nourished individual is more susceptible.     

Nutrition, infection and child growth in Papua New Guinea

Growth patterns of populations in Papua New Guinea (PNG) have traditionally shown considerable variation, with the greatest difference lying between coastal and highland populations. While genetic differences in explaining these patterns cannot be excluded, the generally poor growth relative to western growth references is largely due to the complex interactive effects of undernutrition and infection. The effects of diet, nutrition and infection on the nutritional status of a child vary with age, the general disease ecology and the type and extent of exposure to it, patterns of infant and young child feeding, and types of food consumed. There are two possible ways in which the relationship between undernutrition and infection can begin; one in which poor nutritional status leads to impaired immunocompetence and reduced resistance to infection, and the other in which exposure to infectious disease can lead to a range of factors that reduce food intake, absorption of nutrients, or increase nutrient requirements. In PNG prior to, and at early stages of modernisation, primary malnutrition is likely to have been the usual initiating factor in the onset of growth faltering due to undernutrition-infection interactions. However, the possibility that infection may have been the initiating event in some societies cannot be excluded. This would have happened by way of early dietary supplementation of infants with foods of minor nutritional significance, which could have acted as a vehicle for the introduction of infectious disease to the child. With modernisation and adoption of primary health care principles, earlier supplementation of infant diet than was previously the case became common in PNG. This has lead to general improvements in growth and nutritional status. However, in populations where undernutrition is still common, infection has become more important than primary malnutrition as the initiator of growth faltering due to undernutrition-infection interactions.     

Nutrition of the Fetus and Newborn

Both the successful development of healthy, long-term animal models to study fetal nutrition and metabolism and the improved survival of low-birth-weight, preterm infants have focused interest and research on fetal and neonatal nutrition and metabolism. Such a focus is important, given the recent emphasis on promoting neonatal growth in preterm infants at “normal” in utero growth rates. Estimates of nutrient requirements for growth in a human fetus remain ill defined, however. Body composition data appear biased toward thin infants. Animal data suggest that fetal nutrition proceeds according to species-specific growth rates, with variations in fat content largely dependent on placental fat permeability and on maternal nutrient supply as regulated by the placenta.After birth, neonatal nutrition is affected primarily by food intake and the functional integrity and capacity of the gastrointestinal tract. Additionally, muscle activity, thermoregulation and stresses of various kinds and degrees modify a neonate''s nutritional requirements. Functional deficits of the gastrointestinal tract have been circumvented by a more aggressive use of intravenous nutrition. Both intravenous and enteral nutrient mixtures have been substantially improved in the quantity of all nutrients and have been modified qualitatively toward compositions that are closer to those of human milk. These nutrient mixtures now produce plasma nutrient concentrations that approximate those of a healthy, breast-fed infant.Although such efforts to improve the nutritional balance and growth of preterm infants have been successful, much remains to be learned about the nutritional requirements of sick infants.     

Modelling ungulate dependence on higher quality forage under large trees in African savannahs

In African savannahs, large trees improve grass quality, particularly in dry and nutrient poor areas. Enhanced below-canopy grass nutrients, such as nitrogen and phosphorus contents should therefore attract and benefit grazers. To predict whether ungulates really need these forage quality islands we focused on four grazer species, i.e., zebra, buffalo, wildebeest, and warthog, differing in body size and digestive system. We confronted literature estimations of their feeding requirements with forage availability and quality, observed in three South African savannah systems, through linear modelling. The model predicted the proportion of below-canopy grass that grazers should include in their diet to meet their nutritional requirements.During the wet season, the model predicted that all animals could satisfy their daily nutrient requirements when feeding on a combination of below- and outside-canopy grasses. However, wildebeest, having relatively high nutrient demands, could meet their nutrient requirements only by feeding almost exclusively below canopies.During the dry season, all animals could gain almost twice as much digestible protein when feeding on below – compared to outside-canopy forage. Nonetheless, only warthogs could satisfy their nutrient requirements – when feeding almost exclusively on below-canopy grasses. The other ungulate species could not meet their phosphorus demands by feeding at either site without exceeding their maximum fibre intake, indicating the unfavourable conditions during the dry season.We conclude that grazing ungulates, particularly warthog, zebra, and buffalo, actually depend on the available below-canopy grass resources. Our model therefore helps to quantify the importance of higher quality forage patches beneath savannah trees. The composition of grazer communities depending on below-canopy grasses can be anticipated if grazer food requirements and the abundance of large trees in savannahs are known. The model suggests that the conservation of large single-standing trees in savannahs is crucial for maintenance of locally grazing herbivores.     

Inter-individual variation in nutrient balancing in the honeybee (Apis mellifera)

The Geometric Framework approach in nutritional ecology postulates that animals attempt to balance the consumption of different nutrients rather than simply maximizing energetic gain. The intake target with respect to each nutrient maximizes fitness in a specific dimension and any difference between individuals in intake target therefore represents alternative behavioral and fitness maximization strategies. Nutritional interactions are a central component of all social groups and any inter-individual variation in intake target should therefore have a significant influence on social dynamics. Using the honeybee colony as an experimental model, we quantified differences in the carbohydrate intake target of individual foragers using a capillary feeder (CAFE) assay. Our results show that the bees did not simply maximize their net energetic gain, but combined sugar and water in their diet in a way that brought them to an intake target equivalent to a 33% sucrose solution. Although the mean intake target with respect to the nutrients sucrose and water was the same under different food choice regimens, there was significant inter-individual variation in intake target and the manner in which individuals reached this target, a variation which suggests different levels of tolerance to nutrient imbalance. We discuss our results in the context of how colony performance may be influenced by the different nutrient balancing strategies of individual members and how such nutritional constraints could have contributed to the evolution of sociality.     

Ontogeny of intestinal nutrient transport

Children born prematurely lack the ability to digest and to absorb nutrients at rates compatible with their nutritional needs. As a result, total parenteral nutrition may need to be given. While this nutritional support may be lifesaving, the baby who receives this therapy is exposed to the risks of possible sepsis, catheter dysfunction, and liver disease. The rodent model of postnatal development provides a useful framework to investigate some of the cellular features of human intestinal development. The up-regulation of intestinal gene expression and precocious development of intestinal nutrient absorption can be achieved by providing growth factor(s) or by modifying the composition of the maternal diet during pregnancy and nursing or the weaning diet of the infant. Accelerating the digestive and absorptive functions of the intestine would thereby allow for the maintenance of infant nutrition through oral food intake, and might possibly eliminate the need for, and risks of, total parenteral nutrition. Accordingly, this review was undertaken to focus on the adaptive processes available to the intestine, to identify what might be the signals for and mechanisms of the modified nutrient absorption, and to speculate on approaches that need to be studied as means to possibly accelerate the adaptive processes in ways which would be beneficial to the newborn young.     

The influence of estradiol and diet on small intestinal glucose transport in ovariectomized rats

Although gender differences exist for intestinal absorption of nutrients and drugs, the possible role estradiol may play in modulating nutrient transport has not been established. Therefore, small intestine glucose transport was measured 1 week after administering estradiol to ovariectomized rats fed diets high in carbohydrate (C) or protein (P). Rats treated with estradiol ate 21% less (P<0.05) and lost body mass (7%; P<0.05) but did not have smaller intestines. Administration of estradiol increased rates of glucose transport, but only when the rats were fed the C diet. These findings indicate that estradiol causes a disconnect between food intake and the dimensions and nutrient transport capacities of the small intestine. Furthermore, the responses to estradiol are influenced by diet composition, are not of the same magnitude for rats and dogs, and can be predicted to affect systemic availability of nutrients and drugs.     

Male cockroaches prefer a high carbohydrate diet that makes them more attractive to females: implications for the study of condition dependence

Sexual selection is a major force driving the evolution of elaborate male sexual traits. Handicap models of sexual selection predict that male sexual traits should covary positively with condition, making them reliable indicators of male quality. However, most studies have either manipulated condition through varying diet quantity and/or caloric content without knowledge of specific nutrient effects or have correlated proxies of condition with sexual trait expression. We used nutritional geometry to quantify protein and carbohydrate intake by male cockroaches, Nauphoeta cinerea, and related this to sex pheromone expression, attractiveness, and dominance status. We found that carbohydrate, but not protein, intake is related to male sex pheromone expression and attractiveness but not dominance status. Additionally, we related two condition proxies (weight gain and lipid reserves) to protein and carbohydrate acquisition. Weight gain increased with the intake of both nutrients, whereas lipid reserves only increased with carbohydrate intake. Importantly, lipid accumulation was not as responsive to carbohydrate intake as attractiveness and thus was a less-accurate condition proxy. Moreover, males preferentially consumed high carbohydrate diets with little regard for protein content suggesting that they actively increase their carbohydrate intake thereby maximizing their reproductive fitness by being attractive.     

Tolerance for Nutrient Imbalance in an Intermittently Feeding Herbivorous Cricket,the Wellington Tree Weta

Organisms that regulate nutrient intake have an advantage over those that do not, given that the nutrient composition of any one resource rarely matches optimal nutrient requirements. We used nutritional geometry to model protein and carbohydrate intake and identify an intake target for a sexually dimorphic species, the Wellington tree weta (Hemideina crassidens). Despite pronounced sexual dimorphism in this large generalist herbivorous insect, intake targets did not differ by sex. In a series of laboratory experiments, we then investigated whether tree weta demonstrate compensatory responses for enforced periods of imbalanced nutrient intake. Weta pre-fed high or low carbohydrate: protein diets showed large variation in compensatory nutrient intake over short (<48 h) time periods when provided with a choice. Individuals did not strongly defend nutrient targets, although there was some evidence for weak regulation. Many weta tended to select high and low protein foods in a ratio similar to their previously identified nutrient optimum. These results suggest that weta have a wide tolerance to nutritional imbalance, and that the time scale of weta nutrient balancing could lie outside of the short time span tested here. A wide tolerance to imbalance is consistent with the intermittent feeding displayed in the wild by weta and may be important in understanding weta foraging patterns in New Zealand forests.