Variation In Food Consumption Research Articles

Food Consumption by In Situ Pen-Cultured Planktivorous Fishes and Effects on an Algal Bloom in Lake Taihu, China

ABSTRACT Silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) were used as a new pen-cultureed biomanipulation technique to control algal blooms in Meiliang Bay of Lake Taihu. In order to evaluate the capacity of these two fishes to decrease algal blooms, die1 feeding samplings were carried out in May (without algal blooms) and September (with algal blooms) in 2005. Based on estimated food consumption by the Elliott-Persson model, silver carp increased daily food consumption from 2.07 g dry weight per 100 g wet body weight in May before the outbreak of algal blooms to 4.98 g dry weight per 100 g wet body weight in September during algal blooms outbreak. However, no obvious variation of food consumption was observed in bighead carp during the study period. This species 1.88 and 1.54 g dry weight of plankton per 100 g wet body weight in May and September, respectively. Silver carp had a higher feeding capacity for plankton than bighead carp. Biotic factors (i.e., fish size and conspecific competition with natural species in the lake) may affect the feeding behaviors of both carps as well as seasonal variation of plankton communities in the pen.

Growth rate of tank-reared Mediterranean amberjack, Seriola dumerili (Risso 1810) fed on three different diets

Mediterranean amberjack Seriola dumerili (Risso 1810) has aquaculture potential. The growth rate and food conversion ratio of S. dumerili on three different types of food (A: 100% frozen sardines; B: 50% frozen sardines and 50% pellet C: 100% pellet) were measured, and analysed with respect to temperature, condition index and chemical composition of the fish fillet. Wild S. dumerili, average body weight 248 g and average total length 26.9 cm were caught in August and September 1994 in the South Adriatic Sea near Dubrovnik, Croatia and kept in three tanks (n = 15 in each tank; duration of experiment, 226 days). The fish that were fed on diet A [initial weight, 252 +/- 71 g; total length (TL), 24.3 +/- 2.6 cm] started feeding immediately; however, fish assigned to diet C began to feed entirely on the pelleted diet 1 month after the start of the experiment. The mortality of fish fed on diet A was negligible, the registered growth rate was 313 +/- 74 g (124.2%), specific growth rate was 0.32% day(-1) and the food conversion rate was 6.7. The fish fed on diet B (initial weight, 246 +/- 74 g; TL, 28.2 +/- 2.5 cm) started to feed on day 3 and achieved a total growth rate of about 98% (final weight gain, 241 +/- 69 g) and specific growth rate of 0.24% day(-1) (feed conversion rate of 9.00 and mortality 13%). The fish fed on diet C (initial weight, 246 74 g; TL, 28.2 2.5 cm) started to feed on the pellets after I month and had a growth rate of 87% (weight gain 214 +/- 85 g), a specific growth rate of 0.24% day(-1) and a food conversion rate of 10.6 with considerable mortality (27%). In all three diet groups the fish grew with considerable variation in food consumption and growth rate, depending on seasonal temperature variations of the ambient sea water supplied to the rearing tanks. Chemical analysis showed that the protein level (amount) in the fish meat exceeded 20% in all three fish fillet samples.

Diet and Prey Selectivity by Age-0 Brown Trout (Salmo TruttaL.) in Different Lowland Streams of Lithuania

In Lithuania brown trout (Salmo trutta L.) is the dominant species in fish communities of cold-water streams. We documented a variation in food consumption and prey selection by age-0 brown trout (...

Cyclic fluctuations of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase in aortic smooth muscle cell cultures

The cyclic fluctuations of HMG-CoA reductase activity and mRNA are reportedly related to feeding the cells in culture or to variations in food consumption by the animals over a 24-h cycle. In this work, we demonstrate cyclic increments in HMG-CoA reductase activity in smooth muscle cells (SMC) not associated with the culture feeding. Since reductase activity also shows a marked rise preceding the S phase, one of the major goals of the present work was to evaluate this dual role of reductase activity and mRNA fluctuations related to the cell cycle and to food intake in the SMC-C/SMC-Ch cultures derived from control-fed (SMC-C) and cholesterol-fed (SMC-Ch) chicks. The period and amplitude oscillations in HMG-CoA reductase activity varied depending on culture conditions: lipoprotein-deficient serum vs. FBS, young vs. senescent cells, or confluent vs. nonconfluent cultures. The HMG-CoA reductase mRNA concentration showed a marked rise after feeding not correlated to the fluctuation activity, suggesting posttranscriptional modulation. Reductase activity and mRNA were down-regulated in SMC-Ch. Since the nutritional culture conditions were the same in both cell lines, these findings indicate that consumption of a high-cholesterol diet by the animals prior to the establishment of the SMC cultures induced changes in the HMG-CoA reductase gene expression in-aortic SMC.

Large Within-Day Variation in Cyclosporine Absorption

With the recent focus of monitoring cyclosporine (CsA) therapy using measures of CsA absorption, it is important to understand published reports of diurnal variation in CsA exposure. In 10 renal transplant patients, CsA concentrations were measured 0, 1, 2, 3, and 4 h after both the morning and the evening doses and in a repeat session at least 1 wk later. Both area under the curve for the final 4 h after cyclosporine dose and cyclosporine concentrate 2 h after the cyclosporine dose were more than two-fold higher after the morning dose in both sessions. Because the morning levels were collected in a fasted condition and the evening ones in a fed condition, the study was extended to collect evening levels after fasting. The area under the curve for the final 4 h after cyclosporine dose and cyclosporine concentrate 2 h after the cyclosporine dose values observed now were comparable to the morning fasted values. That the large diurnal variation was due to variation in food consumption, as opposed to a biologic circadian rhythm affecting CsA absorption, has significant implications for therapeutic drug monitoring.

Inter-household variation in adoption of cash cropping and its effects on labor and dietary patterns: a study in a Li hamlet in Hainan island, China

Following the economic development policy of China since the 1980s, the indigenous food production systems of communities have been transformed to a market economy. The introduction of cash crops has been the major developmental policy of China’s rural areas. Despite the overall improvement of economic status among farmers over the last two decades, inequality among households has emerged as a new problem. In the present study, we investigated the process of how cash crops were accepted in a Li hamlet in Hainan island, China, and how this has influenced the labor and dietary patterns of people. In examining this process, we focussed on inter-household differences. We also reconstructed the demographic changes and land use patterns of all the households of the hamlet for the period between 1985 and 2004. Data on labor and diet of 11 representative households were collected by direct measurement/observation from a total of 12 months of fieldwork in 2000–2004. Reconstruction of the adoption process revealed two important factors that might contribute to current variation among households: (1) the success of pioneering households, which played an important role in triggering the hamlet-level adoption of cash crops, and (2) the availability of labor resources during 1995–2004, which explains the inter-household variation observed in 2004. The households that succeeded in cash cropping appeared to be able to afford further investment in cash cropping, which may have further enlarged inter-household variation. Inter-household variation in cash cropping in 2004 partly explains inter-household variation in food consumption and labor hours. The intensification and maintenance of rice cultivation may alleviate the nutritional (initial phase) and work burden posed by the adoption of cash cropping.

Meta-ecosystems and biological energy transport from ocean to coast: the ecological importance of herring migration

Ecosystems are not closed, but receive resource subsidies from other ecosystems. Energy, material and organisms are moved between systems by physical vectors, but migrating animals also transport resources between systems. We report on large scale energy transport from ocean to coast by a migrating fish population, the Norwegian spring-spawning (NSS) herring Clupea harengus. We observe a rapid body mass increase during parts of the annual, oceanic feeding migration and we use a bioenergetics model to quantify energy consumption. The model predicts strong seasonal variation in food consumption with a marked peak in late May to July. The copepod Calanus finmarchicus is the most important prey and 23 x 10(6) tones (wet weight) of C. finmarchicus is consumed annually. The annual consumption-biomass ratio is 5.2. During the feeding migration 17% of consumed energy is converted to body mass. The biomass transported to the coast and left as reproductive output is estimated from gonad weight and is about 1.3 x 10(6) tones for the current population. This transport is to our knowledge the world's largest flux of energy caused by a single population. We demonstrate marked temporal variation in transport during the last century and discuss the effects of NSS herring in the ocean, as a major consumer, and at the coast, where eggs and larvae are important for coastal predators. In particular, we suggest that the rapid decline of lobster Homarus gammarus landings in Western Norway during the 1960s was related to the collapse of NSS herring. We also discuss spatial variation in energy transport caused by changed migration patterns. Both climate and fisheries probably triggered historical changes in the migration patterns of NSS herring. New migration routes emerge at the level of individuals, which in turn determines where resources are gathered and delivered, and therefore, how meta-ecosystems function.

Methodologic Considerations in Descriptive Food-Consumption Surveys in Developing Countries

This paper reviews some methodologic issues relative to food-consumption studies in developing countries, including sampling considerations; capturing temporal variation in food consumption; choice of dietary instruments and protocols; and food-composition databases and needs for adequate software interfaces. Increasingly, issues of cross-country and regional comparability in food-consumption data are now coming into the decision mix. Comparability of data across countries requires comparability of several fundamental systems. Specific countries and cultural contexts must tackle problems of how to estimate individual intakes when one-dish serving is the norm; how to keep up with rapidly changing food supplies; how to capture ingredients added at the table that may be concentrated sources of nutrients or other components of interest; and how to document out-of-home eating. Assumptions about error, bias, and intra-individual variation in food intake need to be thoroughly tested in developing-country contexts. There is an urgent need for improvement in the availability of appropriate food-composition databases and software interfaces for developing-country use.

Feeding energetics of the Norway lobster,Nephrops norvegicusin the Firth of Clyde, Scotland

Abstract The diet of the Norway lobster Nephrops norvegicus in the Firth of Clyde consists of crustaceans, molluscs, and to a lesser extent polychaetes and echinoderms. The proportion of bivalves was higher in the diet of N. Narvegicus from south of Little Cumbrae than in the diet of N. norvegicus from south of Ailsa Craig which contained larger proportions of echinoderms. This appears to reflect the faunal composition of the areas. There were marked interspecific differences in the energy contents and organic contents of prey organisms. Diel variation in food consumption was investigated in animals trawled at 4h intervals over a 24h period. The results suggested periodicity of foraging with gut contents being lowest during the afternoon. The reasons for this are discussed. The rates of weight-specific oxygen consumption (MO2) were determined for quiescent and for active male and female Nephrops norvegicus. The scope for activity was found to be approximately four times basal metabolism. The recent feeding history was observed to have a marked effect on metabolic rate. The MO2 significantly decreased following 8 and 12 weeks of starvation, and rapidly increased again after re-feeding. An energy budget was constructed for Clyde Sea Nephrops norvegicus. The scope for growth was significantly greater for animals in May than November. No significant differences in scope for growth were found between animals from the Little Cumbrae and Ailsa Craig sites.

Experimental provisioning increases play in free-ranging meerkats

The sensitivity of play to variations in food availability has been cited as evidence of the costliness of play, since energetically stressed animals dispense with costly behaviours. However, the causality of the relationship between nutrition and play has not been adequately tested. Using weight gain as a measure of food intake, we documented the food consumption of free-ranging meerkat, Suricata suricatta, pups and found that long-term nutritional status (weight gain over a 6-week period) was positively correlated with rates of play. We confirmed the causality of this relationship by conducting long-term (4–8 weeks) provisioning experiments that raised the nutritional status of experimental pups, subadults and adults. Experimental animals more than doubled their rate of play compared with their nonprovisioned controls. Short-term variations in food consumption (daily weight gain) were not correlated with subsequent rates of play, and we used a short-term feeding experiment to document the transitory effects of hunger satiation. We established that an increase in available energy contributed to the increase in rates of play, rather than the animals simply having more time available to play as a result of being released from the constraints of foraging. We conclude that play in meerkats was energetically costly, and must be adaptive given that the cost of play to juveniles (in terms of future reproductive success) was potentially high. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

The relationship between individual consumption and growth in juvenile turbot, Scophthalmus maximus

The development of feeding hierarchies was investigated in juvenile turbot, Scophthalmus maximus (Rafinesque) held at two rearing densities for 82 days. Individual biometrics were measured on five occasions and a diet labelled with ballotini glass beads was used in combination with a noninvasive radiographic technique to estimate consumption rates. The results demonstrate that the inclusion of the radio-opaque glass beads in the diet did not significantly reduce consumption by turbot. A significant relationship was found between individual consumption and growth of juvenile turbot. A weight differential within groups increased with time and was largely explained by inter-individual variation in food consumption. This differential was driven by an uneven distribution of food within groups, where individuals of a higher weight than the group average consistently consumed a greater than average share of the group meal, and showed less day to day variation in consumption than their smaller counterparts. The results demonstrate that in captive turbot groups, size hierarchies are mediated, at least in part, through inter-individual differences in food consumption.

Seasonal variation in the dietary sources of energy for pregnant women in Lungwena, rural Malawi

We conducted a nutritional survey to describe monthly variation in food consumption among subsistence farmers in Malawi, Southeastern Africa. Of special interest was the identification of foods whose intake changes contributed most to the seasonal fluctuation of overall energy intake. For this purpose, dietary intakes of 593 pregnant women were analysed with 24‐h recall methodology. Mean daily energy intakes varied from 1520 kcal/woman in February (rainy season) to 2250 kcal/woman in April (post‐harvest period). On average, maize provided two‐thirds (63%) of the energy. Other important sources were roots and tubers (11%), fish (5%), fruit (4%), legumes (4%) and vegetables (3%). The rainy season decrease in energy intakes was associated with a marked reduction in the consumption of roots and tubers, fruit, legumes and vegetables. Storage of selected food items and development of agricultural market could alleviate nutritional problems associated with climatic seasonality in rural Malawi.

Evaluating biological significance of chemical exposure to fish using a bioenergetics-based stressor-response model

We demonstrate how contaminant exposure-response relationships can be integrated with a bioenergetics model to estimate the biological significance of sublethal exposure under fluctuating environmental conditions. The integrated bioenergetics-based stressor-response model (SRM) was evaluated by comparing observed and predicted growth of largemouth bass (Micropterus salmoides) exposed to several dieldrin concentrations and by conducting sensitivity analyses. Predictions of the SRM suggest that energetic effects of exposure of largemouth bass to ambient concentrations of dieldrin in lakes at the Rocky Mountain Arsenal National Wildlife Refuge are not biologically significant because the amount of energy lost by resident fish is small compared with variation in food consumption. Furthermore, influence of dieldrin exposure is small compared with the effects of a natural stressor like water temperature. The SRM provides a general framework for integrating laboratory-derived exposure-response relationships with ecological processes to determine the biological significance of multiple stressors in a natural environment. Comparisons of relative effects of anthropogenic and natural stressors can be used to assess potential costs and benefits of alternative ecosystem management strategies.

Evaluating biological significance of chemical exposure to fish using a bioenergetics-based stressor-response model

We demonstrate how contaminant exposure-response relationships can be integrated with a bioenergetics model to estimate the biological significance of sublethal exposure under fluctuating environmental conditions. The integrated bioenergetics-based stressor-response model (SRM) was evaluated by comparing observed and predicted growth of largemouth bass (Micropterus salmoides) exposed to several dieldrin concentrations and by conducting sensitivity analyses. Predictions of the SRM suggest that energetic effects of exposure of largemouth bass to ambient concentrations of dieldrin in lakes at the Rocky Mountain Arsenal National Wildlife Refuge are not biologically significant because the amount of energy lost by resident fish is small compared with variation in food consumption. Furthermore, influence of dieldrin exposure is small compared with the effects of a natural stressor like water temperature. The SRM provides a general framework for integrating laboratory-derived exposure-response relationships with ecological processes to determine the biological significance of multiple stressors in a natural environment. Comparisons of relative effects of anthropogenic and natural stressors can be used to assess potential costs and benefits of alternative ecosystem management strategies.

The Effect of Ration on Behaviour, Food Consumption and Growth in Juvenile Greenback Flounder (Rhombosolea Tapirina: Teleostei)

This study examined the relationships between food ration, intra- and interindividual variation in food consumption, observed behaviours and the growth of individual juvenile greenback flounder (Rhombosolea tapirina: Teleostei) held singly and in groups. Agonistic, feeding and neutral behavioural units were identified and described using video records and focal sampling. Agonistic behaviour, including nipping and pushing, were infrequent and accounted for <5% of behavioural units. The influence of food ration upon agonistic behaviour was investigated using three groups of six flounder offered either a low, medium or high food ration. The total number of agonistic behaviours recorded in each group did not differ significantly (P>0.05) suggesting food ration had little influence upon the total number of agonistic behaviours performed. Single flounder showed less intra- and less interindividual variation in day-to-day food consumption than in groups of six. Variation in food consumption increased with increasing food ration in single and in groups of flounder. Significant positive correlations between food consumption, intraindividual variation in food consumption and specific growth rate provided indirect evidence for the presence of feeding hierarchies. The small contribution made by agonistic behaviour to the total number of behaviours recorded for each group suggests exploitation competition, as opposed to interference competition, was the dominant competitive mechanism employed by juvenile greenback flounder.

Variation in food consumption, growth, and growth efficiency among juvenile hybrid sunfish held individually

Daily food consumption, growth, and gross growth efficiency (GGE) were studied in juvenile hybrid sunfish (female green sunfish, Lepomis cyanellus×male bluegill, Lepomis macrochirus) fed ad libitum and held individually for 112 days. There were substantial inter-individual differences in food consumption; mean specific daily ration differed significantly ( P<0.01) among individuals, and cumulative consumption differed up to four-fold. Specific growth rates differed more than three-fold among individuals, and GGE differed by a factor of two. Consumption, growth, and the GGEs of individual fish were significantly correlated with their initial body weights ( P<0.05). Together, these results suggest that more attention should be given to inherent variation among individuals and that there may be a potential for reducing inter-individual variation and improving the growth of hybrid sunfish in aquaculture by removing small fish early in grow-out.

Regionality of food consumption

Understanding food consumption patterns around the United States is important for food marketers and researchers. A cluster analysis of the food purchases in 126 categories across 54 markets found 11 market groupings that are quite different from those commonly used in demand studies. These new regions were consistent with the findings from some cultural geographers and explained more of the regional variation in food consumption than the standard set of geographic boundaries. Food marketers could use these clusters to balance experiments, identify local marketing opportunities, and segment the US market into geographies with similar food demand patterns. © 1998 John Wiley & Sons, Inc.

Individual variation in food consumption and food preferences in St Lucia parrots Amazona versicolor at Jersey Wildlife Preservation Trust

Individual food consumption and food item preference of 12 St Lucia parrots Amuionu vrrsicolor were studied at Jersey Wildlife Preservation Trust. Diet offered contained a maximum of 29 foods, mostly fruits, vegetables and pulses but also processed foods and commercial parrot pellets. Each day all birds were presented with the same selection of foods and no novel items were introduced during the study period. Birds varied in their average food intake per feeding session (mean ± SD) from 15.1 ± 5.6 g kg‐1 to 89.0 ± 138.3 g kg‐1. Diversity of food items eaten per session was determined by the Simpson's index of diversity. Food preferences were measured by Ivlev's electivity indices from the total amount of each food type consumed relative to the total amount of that food type offered during all sessions. Foods were classified as ‘disliked’ when electivity indices were negative and ‘rejected’ if not consumed at all. The order in which food types were consumed by each parrot was also analysed. Results showed that diet diversity and food intake were significantly higher for ♀♀ than ♂♂. Wild‐born parrots consumed less but ate a wider variety of foods than captive‐born ones. Significant sexual differences in overall food intake as well as in the percentage of disliked and rejected foods were found among captive‐born birds but not in wild‐born parrots. However, because all wild‐born birds in the present study were twice as old as the captive‐born ones, age of bird and origin were confounded variables. Older birds disliked less foods than younger ones but younger parrots ate more than older birds. Within paired birds, ♀♀ were more aggressive towards ♂♂ than vice versa. This may have influenced the lower feeding levels observed by subordinate ♂♂ but single ♂♂ ate even less than those kept in pairs. The results of this study suggest that it is not possible to make generalizations to satisfy optimal diet requirements of the species because of the considerable individual variation found. Quantifying intake and preference from direct observations of the birds during feeding can be a useful technique to help with the formulation of diets. Further studies are required to determine the roles of sex, age and origin on food consumption and preference. The behaviour of paired and single birds should also be assessed in order to identify suitable methods for feeding dominant and subordinate birds in an attempt to optimize nutritional intake of each individual.

The Effect of Decreased Ration on Feeding Hierarchies in Groups of Greenback Flounder (Rhombosolea Tapirina: Teleostei)

The aims of the present study were to investigate food consumption, growth and the dynamics of feeding hierarchies in the same groups of juvenile greenback flounder (Rhombosolea tapirina:Teleostei) fed either high or low rations. Differential food consumption by individual greenback flounder held in groups of 20 showed the presence of feeding hierarchies in which individuals consumed between 0 and 22% of the available food. Inter-individual differences in food consumption resulted in different growth rates leading to growth depensation (measured as an increase in the coefficient of variation for weight). Intra-individual differences in food consumption tended to be larger for flounder which consumed a lower share of the available food. When the group ration was reduced the inter-individual and intra-individual variations in food consumption increased. Consequently, the relationship between inter-individual and intra-individual variation in food consumption tended to become stronger at lower food availability and indicated an increase in the strength of the feeding hierarchies. This study suggests that individual differences in food consumption, mediated through exploitation competition, contribute to growth depensation in this species of flatfish.

Density-Dependent Development in Wyeomyia smithii (Diptera: Culicidae): Intraspecific Competition Is Not the Result of Interference

Density-dependent development in the pitcher plant mosquito, Wyeomyia smithii (Coquillett), indicates variation in competitive ability both within and between populations. We tested 2 disparate populations of W. smithii for 3 types of interference competition: chemical and encounter competition and cannibalism. We found no significant effects of any of these interference mechanisms or variation in food consumption within or between populations. We suggest that asymmetric competition in W. smithii is more likely the result of differences in assimilation or use of assimilated resources than to larval interference or differential ability to consume food.