Variation In Food Composition Research Articles

Food and feeding habits of the Nile tilapia Oreochromis niloticus (Linnaeus, 1758) from Ribb reservoir, Lake Tana sub-basin, Ethiopia

This study aimed to examine the food and feeding habits of Oreochromis niloticus at the Ribb reservoir for sustainable management. A total of 512 specimens were collected using gillnets of different mesh sizes. Of these, 348 (67.9 %) fish had different foods, while 164 (32.1%) fish had empty stomachs. Mud was the main food item that accounted for 89.1% of estimated stomachs and 55.1% of the total volume in the diet. Detritus and phytoplankton were the second most important food items contributing 25.1% and 14.1% of the total volume respectively. Prey items differed depending on the fish size (ANOVA, p < 0.05). The smallest-sized fish preferred detritus, zooplankton, and mud while the food items such as mud and phytoplankton were preferred by the larger-sized fish species from the Ribb Reservoir. The seasonal variations in food composition were observed (ANOVA, p < 0.05). The volumetric contribution of foods such as mud and detritus were higher in the dry season and contributed in 61.2% and 19.2% respectively. During the wet season, phytoplankton and detritus were the most important food items and their corresponding volumetric contributions were 52.3% and 42.1% of the total volume in the stomach O. niloticus Generally, O. niloticus exhibited omnivorous feeding habits in their diet from the newly established Ribb Reservoir. It is possible to conclude that food and feeding habits of O. niloticus influenced by seasons, and fish sizes from Ribb Reservoir. Therefore, water buffer zone management is needed to improve the food and feeding habits of this fish for the better sustainable utilization.

Parasitic Infection Patterns in Coleodactylus Meridionalis (Squamata: Sphaerodactylidae) from Atlantic Forest Fragments, Northeast of The Neotropical Region.

SummaryStudies that seek to understand which factors influence the patterns of infection in the lizard Coleodactylus meridionalis are non-existent. In this way, we recorded the infection rates for these lizards from three different sized fragments of the Atlantic rainforest and investigated if there is influence of the size, mass and sex of the host regarding the endoparasite abundance. In addition, we investigated if there were possible associations between the host’s diet and parasitism, by calculating the diet niche breadth (based on the prey number of pooled stomachs) for each host population and comparing the diet between fragments and sexes (from the three sampled fragments). We collected 38 lizards across the three sampled forest fragments. We only found parasites in the lizards sampled from the smallest of the three forest fragments which included: Physaloptera lutzi, Haplometroides odhneri and Oligacanthorhynchus sp. For this population, lizards with greater length and body mass have a greater endoparasite abundance. In addition, based on the results obtained in our study, the diet of the lizards varies in food composition between sampled populations. Finally, knowing that among the infected lizards there is no sexual dimorphism in relation to size and body mass and that the stomach sampling for this population is insufficient to calculate the indexes related to the food niche; we used the number of prey lizards from all populations, thus we were able to associate the fact that female lizards have a greater endoparasite abundance due to variations in food composition between sexes.

A Seven-Year Longitudinal Study on the Food Habits of the Asiatic Black Bear (Ursus thibetanus) in Relation to Mast Production in Shirakawa Village, Gifu Prefecture, Japan

We examined the food habits of the Asiatic black bear in relation to availability of main foods (seeds of Fagus crenata, Quercus crispula, and Q. serrata) from 1213 scats in Shirakawa Village, Gifu Prefecture, Japan, over seven years. The study area comprises natural forest (approximately 88%) and had little bear-human conflict. The food composition was different in all months over the years. The bears mainly fed on green vegetation in spring, until the end of July, and on hard mast in autumn when its production was abundant. Insects, such as the Formicidae family, made up a higher proportion of the diet from July to August. In autumn of low hard-mast production, the bears consumed various fleshy fruits. The annual variation in food composition was especially greater in September because of the fluctuation in fruit production rather than a phenological time lag.

Diet differentiation between European arvicoline and murine rodents

Small European muroid rodents are generally divided into species which feed on seeds and/or invertebrates and species which feed on green plant material; however, there is considerable plasticity in feeding behavior among species. Here, we analyze diets of 14 low-latitude rodent species from Western Europe based on published studies. The 77 studies were submitted to principal component analysis in order to compare diet plasticity within and between the 14 species. We observed variations in food composition of arvicoline and murine rodents which are associated with differences in morphology and habitat use. Most arvicoline rodents eat mainly green matter of the herbaceous layers of open habitats whereas most murine species are able to use a greater diversity of high energetic plant tissues from denser habitats, where they can exploit the different vegetation layers. Despite its phylogenetic position among arvicoline rodents, the bank vole (Myodes glareolus) shows morpho-physiological and ecological traits which tend to be more similar to murine species. These intermediate evolutionary characters seem consistent with the fact that bank voles are able to exploit a wide spectrum of trophic resources from low energetic lignified tissues to high calorific invertebrate prey. This results in a very diverse diet, which is intermediate between true herbivorous arvicolines and typical seed- and invertebrate eating murine species. More investigations on genetic affiliation and ecological driving forces will help understand this intermediate position of bank vole diet, and further investigations among other arvicoline species will help determine if bank voles and other Myodes species are unique.

Fully reversible phenotypic plasticity of digestive physiology in young house sparrows: lack of long-term effect of early diet composition

Feeding conditions during the nestling period may significantly affect whole-life fitness in altricial birds but little is known about the physiological mechanisms responsible for these effects. Permanent changes (irreversible developmental plasticity) in digestive physiology caused by the neonatal diet may form such a mechanism. We previously showed that the lack of starch in the diet of house sparrow (Passer domesticus) nestlings between 3 and 12 days post-hatching significantly decreased the activity of intestinal maltase, an enzyme essential for starch digestion. To check whether diet-induced variation in maltase activity in young house sparrows is reversible, we raised them under laboratory conditions from 3 until 30 days of age on diets with either 0% starch or 25% starch, with some individuals experiencing a switch in their assigned diet at 12 days of age. We found evidence for the presence of an internal, presumably genetic, program for changes in the activity of maltase and sucrase, which was, however, significantly affected by diet composition (i.e. environmental factor). Digestive enzyme activity in 30 day old birds was not influenced by diet composition prior to day 12 but instead depended only on diet that was fed between days 12 and 30. We conclude that plasticity in the activity of intestinal disaccharidases in house sparrow nestlings represents completely reversible phenotypic flexibility that can help young sparrows to cope with unpredictable variation in food composition during ontogeny without long-term effects on their digestive system. However, comparison with other species suggests that the magnitude of digestive flexibility in young passerines may be evolutionarily matched to species-specific variation in feeding conditions.

Wintering ecology of the Black Stork (Ciconia nigra) in Beijing

The Black Stork (Ciconia nigra) is a new winter resident in Beijing due to temperature changes. To understand the wintering ecology of this species better, a field survey covering the number of birds of this population, habitat selection, feeding activity and grouping behavior was conducted at the Shidu Nature Reserve from January 2004 to March 2009. The results show that the Black Stork selected the Juma River at this nature reserve as their new winter habitat. The number of birds in this population decreased from 28 in the 2004/2005 winter to 17 in the 2007/2008 winter with a subsequent recovery to 23 the following year. The wintering flock was formed in mid-November and dispersed in mid-March, but the date changed with seasonal temperature fluctuations. The storks exhibited feeding habitat fidelity and the main food type was fish (> 92.4%). There was no significant variation in food composition between adults and sub-adults (Mann-Whitney U test, U = 1.00, p = 0.44). Feeding activity occurred in the morning and at noon during early winter, but concentrated in the afternoon during mid winter, divided into dawn and dusk in late winter. Daily fish intake was 538 g for adults and 449 g for sub-adults if the period of foraging reached six hours in the wild, which was similar to the level under artificial feeding. Agonistic behavior among feeding birds was observed among group members in late winter. The main negative factor for wintering Black Stork was a reduced feeding habitat resulting from increased water depth due to damming of the river to benefit tourism and to wetland exploitation.

Probabilistic risk assessment of dietary cadmium in the South Korean population

Global interest in the adverse health effects of cadmium (Cd) has focused on dietary exposure as the principal source of Cd exposure to the general population. Common assumptions used in deterministic Cd assessment in global or regional diets have limitations when applied to specific national cases where local variation in food composition and consumption patterns are different than for global or regional norms. Stochastic dietary Cd exposure assessment was conducted for the general South Korean population to understand better Cd dietary intake. Because rice (Oryza sativa) is commonly and highly consumed by Koreans, it was the dominant contributor to Cd in the diet, representing on average 25% of the total dietary exposure for the general population. Hazard index (HI) values were below the level of concern for the 95th percentile of the general population. Sensitivity analyses demonstrated that variation in rice intake and Cd concentration had the greatest influence on the Cd risk estimate for the general population. Changes in food sources, such as the use of imported rice with higher Cd levels, would lead to increased Cd exposure in the diet, thus necessitating continued vigilance as to the status of Cd within the food supply.

Cadmium Exposure in the South Korean Population: Implications of Input Assumptions for Deterministic Dietary Assessment

ABSTRACT Dietary exposure to Cadmium (Cd) is of increasing interest globally because of the adverse health effects of Cd arising from multiple sources. The assumptions used when undertaking deterministic assessment of Cd in global or regional diets have implications when applied to specific national cases representing local variation in food composition and consumption patterns different from global or regional norms. We have conducted deterministic dietary Cd exposure assessments for the South Korean population using a variety of schemes for point estimation. Consumption data from the Korean Nutrition Survey (2001 to 2003) and monitoring data from the Korea Food and Drug Administration were used as the basis for the exposure estimates. The average daily per capita Cd exposure was 14 μ g for the South Korean population, representing about 27% of tolerable daily intake (TDI) and is similar to that reported in other countries. The hazard index (HI, the ratio of total Cd exposure to the TDI) typically ranged from 0.3 to 0.9 depending on assumptions used in deterministic estimates of dietary exposure. Even though the current exposure of the South Korean population at large is found to be safe on the basis of these estimates, consideration of high-end patterns of Cd level and consumption suggests the need for continued vigilance in dietary Cd monitoring.

Produits de la pêche et acides gras oméga 3. Intérêt en prévention cardio-vasculaire

Fish products are a major source of long-chain, omega-3 fatty acids. These are mainly responsible of the cardioprotective effect of fish consumption. The first section of the paper reviews the role of polyunsaturated fatty acids in physiology. Then, epidemiological studies demonstrating the protective effects against cardiovascular disease are reviewed, including ecological, case-control, cohort and interventional studies. Their mechanisms act on known risk factors, but mainly on platelet aggregation, plaque vulnerability and arrythmia. This explains their rapid effect in secondary prevention. Food sources, variations in food composition and loss of omega-3 fatty acids in foods are discussed, followed by observed and recommended intakes. In the elderly, alpha linolenic acid intake is often inadequate, making it necessary to provide EPA and DHA directly with fish. Finally, the omega-6/omega-3 ratio must not be too high.

Meso-scale variation in winter food composition of sika deer in Tochigi Prefecture, central Japan

Food habits of sika deer Cervus nippon show great variations at a macro-scale geographical range and some variations even at micro-scale of locations such as islands or mountains, but there is no study at meso-scale. We investigated variation in the food habits of sika deer over a meso-scale range encompassing high mountains and hilly areas in Tochigi Prefecture, central Japan. Rumen contents sampled from deer culled in the winter of 1996 (n = 147) in 10 localities were analyzed using the point-frame method. Local variation in food composition was high. Detrended correspondence analysis (DCA) showed that food composition varied from the western high mountain region, where low quality foods (dead leaves, bark, and culms) were dominant, to northern and eastern areas, where a dwarf bamboo Sasa nipponica, which grew in the understory of oak forests, was dominant. Two intermediate localities between the western and eastern areas and another eastern locality fell between the western high area and the eastern low area in the ordination. The proportion of S. nipponica varied from 0% to 99% among all samples, and from 0.5% to 60% among the 10 localities. S. nipponica occupied >50% of rumen contents in 52 samples (35.4%). Thus, the food habits of sika deer varied greatly, even within a meso-scale range of 2000 km2, depending on food availability in the different habitats.

Diets of Two Lemur Species in Different Microhabitats in Beza Mahafaly Special Reserve, Madagascar

Studies of primate diets usually focus on differences that distinguish species or populations. However, variation in diet can occur at a more local level of groups within a population, especially in a non-homogeneous habitat. I compared dietary variation in food composition and toughness across groups of 2 lemur species in Beza Mahafaly special reserve, Madagascar. Beza Mahafaly contains an 80-ha reserve (Parcel 1) that, while small, hosts a dense population of Lemur catta (ring-tailed lemurs) and Propithecus verreauxi verreauxi (sifakas). Microhabitats in the eastern vs. western sides of the parcel are structurally and floristically distinct. Sifakas in this parcel have small, discrete home ranges and are morphological folivores. For these reasons, I expected that the 6 groups studied would eat a different menu of food plants but with similar toughness values. Ring-tailed lemurs have comparatively large, overlapping home ranges, and I expected that the 5 study groups would eat similar foods. Despite living in different microhabitats across the parcel, sifakas exhibit high dietary uniformity both in dietary plant species composition and the toughness of the foods. Food selection in sifakas operates on two distinct levels. Sifaka groups share many key food species that appear independent of local abundances, but the ranking of the foods within each group appears related to availability. Ring-tailed lemur groups are more heterogeneous in the composition of their diets relative to sifakas, though the time spent feeding on individual foods reveals a marked preference for the fruits of Tamarindus indica by all groups. Food toughness is consistent across the parcel with the exception of the most western group. Ring-tailed lemurs are highly specific feeders, but indiscriminate nibblers. Sifakas are targeted, balanced feeders. There does not appear to be a consistent microhabitat effect operating across species. Differences within sifaka and ring-tailed lemur populations in food composition and toughness, however, correspond to an east-west microhabitat gradient. Measures of dietary flexibility must take into account not only the plant species consumed and the different parts eaten but also their associated food properties and proportion of time spent feeding on them.

Feeding habits of John Dory, Zeus faber, off the Portuguese continental coast

The feeding habits of John Dory (Zeus faber) were studied, based on the analysis of stomach contents from fish sampled in five groundfish surveys. These surveys were carried out off the Portuguese coast during different seasons between 1990 and 1992. The main aspects of feeding biology analysed in this paper are: ontogenetic diet changes, temporal variations in food composition and feeding intensity. Multivariate methods were used to investigate ontogenetic diet shifts. Two main length groups were identified: 8.0–24.9 cm fish, feeding mainly on dragonets and silvery pout, and 25.0–55.9 cm fish whose diet was mainly composed of blue whiting and snipefish. A transitional phase (24.0–30.9 cm fish) with a mixed food composition was observed. This ontogenetic diet shift does not seem to correspond to any important change in body morphology but it does coincide with the onset of sexual maturity in the species.John Dory switched from a diet of small prey species with more pronounced benthic behaviour to a diet of larger schooling pelagic species. This suggests parallel evolution to more pelagic foraging behaviour. However, John Dory feeding habits appear to be largely controlled by the availability and accessibility of prey species: (i) the diet of adult John Dory is dominated by very abundant species; (ii) shifts in the main prey items between different times of the year and between different areas seem to be related both with their absolute and relative abundance in the environment and with the overlap between the depth distribution of predator and prey.

Growth and development in the subtropical copepod Acrocalanus gibber

Growth rates of the subtropical copepod Acrocalanus gibber were measured in field incubations. Prosome length of adult females was correlated with rearing temperature, but variation in condition of copepods masked any correlation of temperature with carbon and nitrogen content. The resulting N‐specific growth rates (GN) were log‐linear and ranged from 0.49 to 0.72 d−1 at temperatures of 24.4–29.2°C. Highest growth rates occurred in the middle of the temperature range, but no relationship between Gn and temperature could be established, although molting rate and generation time were correlated with temperature. Growth rate was negatively related to chlorophyll a concentration and was independent of particulate C and N. Nitrogen‐specific egg production, measured either from wild‐caught females or from females produced in the incubations, never exceeded 0.28 d−1 (representing only 46% of GN) and was frequently near zero. In this respect, juvenile growth was less food‐limited than was adult growth (measured as egg production). The measured duration of A. gibber developmental stages, particularly copepodite stages 1 and 5, varied in laboratory experiments, apparently as a result of variation in food composition. Molting rate, copepod weight, and the resulting growth rates appear to be influenced by food quality.

Variations in the diet composition and feeding intensity of mackerel icefish Champsocephalus gunnari at South Georgia (Antarctic)

The diet composition and feeding intensity of mackerel icefish Champsocephalus gunnari around Shag Rocks and the mainland of South Georgia was analyzed from ca 8700 stomachs collected in January/February 1985, January/February 1991 and January 1992. Main prey items were krill Euphausia superba, the amphipod hyperiid Themisto gaudichaudii, mysids (primarily Antarctomysis maxima), and in 1985 also Thysanoessa species. The proportion of krill and T gaudichaudii in the diet varied considerably among the 3 years, whereas the proportion of mysids in the diet remained fairly constant, Krill appears to be the preferred food. In years of krill shortage, such as in 1991, krill was replaced by T gaudichaudii. The occurrence of krill in the diet in 1991 was among the lowest within a 28 yr period of investigation. Variation in food composition among sampling sites was high. This high variation appears to be primarily associated with differences in prey availability, but much less with prey size selectivity. Feeding intensity varied considerably among seasons. It was highest in 1992. The proportion of empty stomachs was uncommonly high and stomach content weight was uncommonly low in January 1991, a period when energy-rich food was needed for the final maturation of gonads. At the same time, an unusually high proportion of sexually mature fish showed no signs of the gonad development necessary for spawning in that season. It was hypothesized that as in some other non-Antarctic fish species the shortage of suitable food may have forced the fish to sacrifice gonad maturation in order to maintain body size.

Observations on the seasonal variations in food composition and some behavioural patterns of Scotophilus h. heathi (Chiroptera: Vespertilionidae) in Rajasthan

Article Observations on the seasonal variations in food composition and some behavioural patterns of Scotophilus h. heathi (Chiroptera: Vespertilionidae) in Rajasthan was published on January 1, 1983 in the journal Mammalia (volume 47, issue 2).