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1.
    
Food consumption and digestion of male and female dugongs (Dugong dugon) was examined by analyzing long-term (1979–1998) feeding records at Toba Aquarium (Japan). Throughout all captive feeding periods, dugongs consumed eelgrass (Zostera marina) and showed steady increases in feed consumption with a consistent weight gain of 42–45?kg a year. The daily consumption of male and female dugongs increased from 10–15?kg to 23–26?kg of fresh eelgrass, accounting for approximately 14 and 7% of their body weight at one and seven years old, respectively. Both dugongs had a marginal dry matter digestibility of over 90%. Food consumption varied between seasons and individuals. There were major reductions (P<0.05) in consumption by the male in November and January and by the female in August and September. The seasonal reductions in food consumption coincided with high digestibility of eelgrass.  相似文献   

2.
Major economic transitions typically entail changes in the availability of and purchasing power for different types of foods leading to long-term changes in the composition of the diet. Bulgaria, a former Eastern Bloc country, underwent a difficult and protracted transition from a centralized to market economy with acute economic crises and a much slower recovery of income levels than in Poland, the Czech Republic, and Hungary. Using annual data from the Bulgarian National Household Survey, we study changes in the reported consumption of major foods (excluding alcoholic drinks) and their constituent macronutrients from 1985 to 2002, examining also the differences in dietary patterns between the period prior to and following the transition. The consumption of most major food items decreased, resulting in a fall in per capita energy consumption of 429 kcal/day (1.80 MJ/d), following the economic transition of 1991. As expected, the consumption of foods that were more expensive per unit of energy decreased greater than cheaper foods, -34% for animal products and -19% for visible fats, but only -10% for carbohydrates. These changes are related to the changes in income and market prices as well as the general negative trend in economic growth and hyperinflation in the mid-1990s. Thus, Bulgaria experienced a decrease in food consumption without significant changes in the dietary pattern following the economic transition of 1991. The fact that part of this decline may be attributed to continued economic challenges suggests that future transitions in the diet may be expected as economic development proceeds.  相似文献   

3.
Alvar grasslands are thin-soil calcareous grasslands on Silurian and Ordovician limestone bedrock. They are considered unique plant communities for northern Europe and America with a high conservation value. Until now, European alvar grasslands have only been described in Sweden and Estonia. We described species-rich alvar grasslands on the Izhora plateau, NW Russia and compared this vegetation with that of Estonian alvar grasslands. Floristic composition and environmental conditions of Russian alvars were similar to Estonian alvar grasslands on thicker dry soil. Russian alvars are isolated from similar communities in Estonia, but extensive transport of domestic animals from Estonia to NW Russia in past centuries has probably enhanced species dispersal. Some characteristic Estonian alvar species were missing in NW Russia because it lies outside their natural ranges. Other differences in vegetation were explained by higher atmospheric nitrogen deposition and younger age of Russian sites. In NW Russia the alvar grasslands were small, but several red-listed plant species were present. In order to preserve European alvar vegetation effectively, Russian alvar grasslands need further study and conservation as an outpost of this threatened vegetation type.  相似文献   

4.
Abstract. Naturaland semi-natural plant communities occurring in the Nile Valley in Upper Egypt are described and their position in the zonation along the river bank interpreted. With the help of ordination and classification methods relationships among the 13 community types and their distribution along the predominating moisture gradient are elucidated. The vegetation of the Nile Valley can be described as a series of discrete plant community types on the basis of their floristic composition, structural components and habitat conditions. The communities can be grouped into four higher units, considered as formations: swamp, meadow, thorn-bush and riverain woodland.  相似文献   

5.
非人灵长类的营养学研究越来越受到国际和国内社会的关注。我国是世界上实验灵长类动物的最大产出国。进一步了解和发展非人灵长类营养学将有利于提高我国非人灵长类的饲养水平和饲料资源的利用效率,推动整体产业的发展。为此本文介绍了近年来国际上非人灵长类营养学方面的研究进展和国家饲料配比的相关规定,阐述了各营养成分的作用、缺乏症状和改善案例。旨在丰富相关方面的科学信息,增加对非人灵长类营养
需求的理解。  相似文献   

6.
Biotechnology products and European consumers   总被引:3,自引:0,他引:3  
More than 100 interviews conducted during 1997 with European food manufacturers and retailers, trade associations, government departments, consumer groups, environmental organizations and some individual academic scientists revealed how differences in the perceived attitudes of consumers gave rise to varying approaches by suppliers to the possible introduction of transgenic foods. European consumers generally are not against the pharmaceutical products of biotechnology but are much less willing to accept food and food ingredients, especially when derived from genetically modified plants. Objections are mainly based on fears for the health and safety of the consumer, worries about the possibility of deleterious effects on the environment, and a range of moral and ethical concerns often deriving from a distaste, however expressed, at the concept of interfering with nature. Consumer understanding of the science underlying biotechnology is patchy; in no country does more than a small proportion of the population claim a good grasp. Partly no doubt as a consequence of these attitudes, the introduction of genetically modified foods into Europe has occurred slowly and, during the period of this study, perhaps only in the Netherlands and the UK.  相似文献   

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食物分享是灵长类动物的一种重要社会交往行为,主要发生在成体-幼体间和成体-成体之间。本文从这两个方面对灵长类动物食物分享的行为表现、特点以及功能进行总结,着重比较了无亲缘关系的成年个体间食物分享的互惠解释和骚扰解释。通过对以上内容的综合分析,进一步提出了食物分享行为的未来研究方向以及对人类合作行为演化的启示。  相似文献   

9.
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Food sharing , defined as allowing others to eat part or all of oneπs own monopolizable food items, is one of the important social interactions in non2human primates. It happens mostly between adults and immatures but rarely among adults, with a common pattern of passive food sharing. Researches on food sharing in non-human primates were reviewed along this two age categories focusing on their characteristics and functional explanations. Food sharing between adults and immatures typically happens between mothers and their offspring, and ecological factors including age of the immatures and the quality and quantity of food, influence the frequency of food sharing. As an important part of infant care, the functional significance of food sharing was usually explained with foraging assistance hypothesis and food learning hypothesis. The mechanism of food sharing is more complex among adults than between adults and immatures, for that it is influenced not only by ecological factors but also by social factors, such as affinitive relationship and social dominance between individuals , as well as social tolerance in the group. As two of the popular explanations for non-kin food sharing among adults, reciprocity explanation and harassment explanation were compared. Reciprocity explanation focuses on the alternation of donor and recipient roles in repeated food interactions and states that an individual may benefits another by relinquishing part of its own food if the recipient returns the favor later. On the other hand, according to harassment model, the owner may allow the beggar to consume a fraction of the food, since the beggarπs harassment is costly. It is suggested that reciprocity requires complex cognitive skills , while harassment has very few constraints and thus should be a better model. In the end, it was proposed that food sharing could be taken as an ideal context in further studies on the social cognition of non-human primates, and researches on food sharing could provide insights into the understanding of the evolution of human cooperation.  相似文献   

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The apparent prevalence of intraguild predation in productive environments has been regarded as puzzling because some simple models suggest that the intraguild prey species is often either reduced in abundance or driven extinct at high resource productivity. While various theoretical mechanisms that avoid this prediction have been uncovered, they have often been viewed as being narrowly applicable. This article examines the fate of the intraguild prey in models in which consumer species may have type-2 functional responses; these are usually characterized by sustained fluctuations in population density at high enough resource productivities. The models also include adaptive, but imperfect diet choice by the top predator. We concentrate on two situations: (1) the prey exhibits less saturation in its functional response to the resource than does the predator and (2) the predator is unable to persist on the basal resource alone. The reasons given by previous studies for discounting these cases are re-examined. The present analysis shows that prey abundance often increases with increasing productivity in both cases, as does the range of prey parameters that allows prey persistence. It is also possible for the prey to coexist with the predator in spite of having a larger equilibrium requirement for the resource. Different assumptions about the dynamics of diet choice can have a large impact on population responses to enrichment. We argue that the persistence and/or increase in abundance of intraguild prey at higher productivity should not be regarded as puzzling because observations are consistent with a range of theoretical models that reflect commonly observed mechanisms.  相似文献   

12.
In natural vegetation, individuals of different species are more often than not distributed contagiously and arranged as patches. In experimental studies on interference between plant species, this aspect has been neglected.In the experimental approach presented here the vegetation (seven plant species characteristic of woodland clearings) consists of a mosaic of hexagons of 16 m2 each, in such a way that each monospecific plot of the honeycomb was surrounded by six hexagons planted with other species. In addition, there were separate hexagons without adjacent neighbours. In this way the fate of plants in plots, with and without the influence of vegetatively expanding neighbours could be compared.Ecological advantages of the method applied are a) a high degree of similarity with natural patterns of vegetation, b) the opportunity for the different species to consolidate their own microhabitat, which might have repercussions with regard to succession, c) the comparability of different monocultures with the corresponding units in the mixture.The species specific plant growth (and concurrent capture of nutrients) played an important role in the mechanism of interference (and subsequent succession). Allelopathic effects cannot be excluded.Nomenclature follows Heukels & Van Ooststroom (1973).The authors are indebted to Drs. A. J. de Neeling for his advice with regard to the experimental set-up.  相似文献   

13.
    
Population dynamics can reflect the body mass distribution of species because there is an allometric relationship between the average body mass of species and its metabolic timescale. Since predators are generally larger than their prey, a hierarchical structure from fast timescales to slow timescales can be a general structure in food webs. In this paper, we show that changes of the metabolic timescale ratio can cause catastrophic shifts. Then, we investigate a two-dimensional parameter space with the timescale ratio and the carrying capacity of basal species, and reveal that the timescale ratio characterizes the response of the system to environmental variation. Finally, in a bistable regime, we try to clarify the relationship between the trophic position of a species and the extent to which the species induces attractor switching. We saw that, in a 4-species food chain, top predators and second consumers induce attractor switching easily compared to first consumers and basal species.  相似文献   

14.
15.
Abstract. Injection of Manduca sexta allatotropin (Manse-AT) into fifth or sixth stadium larval Lacanobia oleracea had no significant effect on larval growth, development or food consumption, compared to control injected insects. In contrast, injection of M. sexta allatostatin (Manse-AS) into fifth stadium larvae resulted in a retardation of growth, reduction in feeding and increased mortality, compared to control injected insects, but had no effect on non-feeding (day 7) sixth instar larvae. Results suggest that Manse-AS is not acting on the corpora allata (CA) to inhibit Juvenile Hormone (JH) synthesis to produce the observed effects, but most likely by its myoinhibiting action on the foregut. Inhibition of foregut peristalsis by Manse-AS in vivo appears to suppress feeding, resulting in increased mortality. Foregut peristalsis may be inhibited by the intact peptide or a deletion peptide produced by cleavage of Manse-AS by haemolymph enzymes, because Manse-AS (5-15) also inhibits muscle contractions in the foregut in vitro .  相似文献   

16.
Although food reward plays a large role in learning and behavioral experiments, there have been few studies examining the most motivating food reward for pigeons. Brown (1969) found that pigeons had a tendency to prefer peas, while Killeen et al. (1993) found pigeons to prefer peas and popcorn in Experiment 1A. We looked to further explore these options as well as expand upon the types of foods examined beyond mainly grains and seeds. Pigeons were presented with six novel foods (granulated peanuts, popping corn, freeze-dried mealworms, bread crumbs, split peas, and sunflower hearts) allocated into two sets of three food items. Once the most consumed food from each food set was determined, they were pooled together with sorghum seeds (a familiar food) to form a third set. Sunflower hearts were the most consumed of all the food items, followed by corn and granulated peanuts. We discuss the potential factors mediating consumption choice, including nutritional profile and food particle size.  相似文献   

17.
    
Many modern cities have strongly invested in the sustainability of their urban water management system. Nordic cities like Stockholm or Copenhagen are amongst pioneers in investments towards integrated urban water management. However, cities can never be fully self-sufficient due to their dependency on external (water) resources. In this paper, we quantify this water dependency with respect to food consumption in nine cities located in the five Nordic countries (Sweden, Denmark, Finland, Norway and Iceland), by means of the water footprint concept. Detailed urban water footprint assessments are scarce in the literature. By analysing national nutrition surveys, we find that urban food intake behaviour differs from national food intake behaviour. In large Nordic cities people eat generally less potatoes, milk products (without cheese), meat and animal fats and they drink less coffee than outside city borders. On the other hand, they generally eat more vegetables and vegetable oils and they drink more tea and alcoholic beverages. This leads consistently – for the six large Nordic cities Stockholm, Malmö, Copenhagen, Helsinki, Oslo and Reykjavik – to slightly smaller food related urban water footprints (−2 to −6%) than national average values. We also analyse the water footprint for different diets based upon Nordic Nutrition Recommendations (NNR) for these cities. We assessed three healthy diet scenarios: 1) including meat (HEALTHY-MEAT), 2) pesco-vegetarian (HEALTHY-PESCO-VEG) and 3) vegetarian (HEALTHY-VEG). This shows that Nordic urban dwellers 1) eat too many animal products (red meat, milk and milk products) and sugar and drink too much alcohol and 2) they eat not enough vegetables, fruit and products from the group pulses, nuts and oilcrops. Their overall energy and protein intake is too high. A shift to a healthy diet with recommended energy and protein intake reduces the urban WF related to food consumption substantially. A shift to HEALTHY-MEAT results in a reduction of −9 to −24%, for HEALTHY-PESCO-VEG the reduction is −29 to −37%, for HEALTHY-VEG the reduction is −36 to −44%. In other words, Nordic urban dwellers can save a lot of water by shifting to a healthy diet.  相似文献   

18.
T. J. Valone  S. L. Lima 《Oecologia》1987,71(2):286-294
Summary In earlier work (Lima et al. 1985; Lima 1985), we found that gray squirrels (Sciurus carolinensis) and black-capped chickadees (Parus atricapillus) when exploiting a patch of food in the open often carried individual food items to protective cover for consumption. Their tendency to carry (i) decreased as distance of the patch from cover increased, and (ii) increased as size of the available food items increased. A simple model indicated that this behavior was consistent with a trade-off between efficient foraging and predation risk. Maximal feeding efficiency was achieved by always eating at the patch, whereas minimal time exposure to predators was achieved by carrying all items to cover for consumption. Because predation-riskrelated trade-offs are likely to be of importance in the determination of feeding behavior, we surveyed the behavior of 10 bird species feeding under similar conditions to assess both the generality of the above results and the adequacy of some simple assumptions concerning the assessment and perception of predation risk.We observed considerable interspecific variability in behavior. Of the 10 species studied, 4 behaved in a manner similar to the squirrels and chickadees. Five other species showed an increased tendency to carry with larger items but no clear tendency to decrease carrying from longer distances. The one remaining species exhibited neither behavioral trend.The model that predicted squirrel and chickadee behavior failed to account for all observed behavior. The behavior of all species, however, was influenced by predation risk, and the discrepancy between theory and observation most likely reflects shortcomings of the model. These discrepancies indicate that other factors, in addition to exposure time, may be of significance in the perception of predation risk by several (or all) of the species studied. Of particular importance may be a distance-dependent probability of escaping attack. Other results indicate that predation risk may influence handling times via aspects of the digestive process.  相似文献   

19.
Nutrition exerts a life-long impact on human health, and the interaction between nutrition and health has been known for centuries. The recent literature has suggested that nutrition could differently influence the health of male and female individuals. Until the last decade of the 20th century, research on women has been neglected, and the results obtained in men have been directly translated to women in both the medicine and nutrition fields. Consequently, most modern guidelines are based on studies predominantly conducted on men. However, there are many sex-gender differences that are the result of multifactorial inputs, including gene repertoires, sex steroid hormones, and environmental factors (e.g., food components). The effects of these different inputs in male and female physiology will be different in different periods of ontogenetic development as well as during pregnancy and the ovarian cycle in females, which are also age dependent. As a result, different strategies have evolved to maintain male and female body homeostasis, which, in turn, implies that there are important differences in the bioavailability, metabolism, distribution, and elimination of foods and beverages in males and females. This article will review some of these differences underlying the impact of food components on the risk of developing diseases from a sex-gender perspective.  相似文献   

20.
黑龙江省通河乌龙狩猎场野猪冬季食性的初步研究   总被引:9,自引:3,他引:9  
王文  马建章  李健  王志平 《兽类学报》2005,25(4):407-409
野生动物食性的研究,在野生动物保护和管理方面具有重要的基础理论意义。野猪(Sus scrofa)是一种经济价值较高的有蹄类动物。国内对野猪食性的报道,仅见综述性献(巫露平,1980;李振营和罗泽殉,1983;杨伯然,1984),野猪食性方面的研究尚未多见;国外对野猪食性的研究主要集中在食物组成的定量分析和食物营养质量的评价(Eriksson and Petrov,1995;Foumier-chambrillon et al.,1995;朝日念,1985)。因此,作从2000~2001年,分别在黑龙江省通河乌龙狩猎场收集粪样,利用粪便显微组织学分析方法并结合野外掘食痕迹对野猪冬季食性进行了初步研究。  相似文献   

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