949 resultados para diet composition


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Se determinó la composición de la dieta de verano de bovinos pastoreando en sistemas formados por bosques de Nothofagus pumilio (lenga) y mallines, del noroeste del Chubut. Se estimó la disponibilidad forrajera de los mallines y del sotobosque mediante cortes de biomasa aérea, y se determinó la composición dietaria mediante análisis microhistológico de heces. La dieta está integrada principalmente por especies de gramíneas y graminoides, que disminuyeron su frecuencia al final del verano, mientras que los renovales de lenga y otras especies leñosas la aumentaron. El ganado selecciona gramíneas en ambos períodos, y al final del verano también los renovales de lenga. La ganadería constituye una importante y creciente forma de subsistencia para los pobladores rurales del noroeste del Chubut. Este trabajo aporta elementos para avanzar en la búsqueda de herramientas que permitan la sustentabilidad de los bosques de lenga.

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El control biológico aumentativo de Diatrae saccharalis Fabricius (Lepidoptera: Crambidae) requiere la cría masiva del parasitoide Cotesia flavipes Cameron (Braconidae: Microgastrinae) y por ello, es necesario el desarrollo de dietas artificiales eficientes. El objetivo fue examinar los efectos de distintos tipos de dieta sobre parámetros biológicos de D. saccharalis y su impacto en la producción de cocones de C. flavipes. Se sembraron 46136 huevos de D. saccharalis en once combinaciones de dietas artificiales, con dos tipos de harinas y tres tipos de antibióticos. Los resultados mostraron que la composición de la dieta afectó los parámetros biológicos de ambas especies. La mayor eficiencia en la cría se obtuvo con el empleo de combinaciones de harina de poroto y ampicilina. Sin embargo, si se considera la relación entre costos de producción y parámetros biológicos, la dieta con harina de poroto, oxitetraciclina y estreptomicina resulta más adecuada para la cría masiva.

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In order to investigate the diversity of diet composition in macrobenthic peracarid crustaceans from the Antarctic shelf and deep sea, the fatty acid (FA) composition of different species belonging to the orders Isopoda, Amphipoda, Cumacea and Tanaidacea was analysed. Multivariate analyses of the FA composition confirmed general differences between the orders, but also distinct differences within these orders. To gain information on the origin of the FAs found, the potential food sources sediment, POM and foraminiferans were included in the study. Most of the analysed amphipod species displayed high 18:1(n-9)-18:1(n-7) ratios, widely used as an indicator for a carnivorous component in the diet. Cumaceans were characterised by increased phytoplankton FA markers such as 20:5(n-3) (up to 29% of total FAs), suggesting a diet based on phytodetritus. High values of the FA 20:4(n-6) were found in some munnopsid isopods (up to 21% of total FAs) and some tanaidacean species (up to 19% of total FAs). 20:4(n-6) also occurred in high proportions in some foraminiferan samples (up to 21% of total fatty acids), but not in sediment and POM, possibly indicating the ingestion of foraminiferans by some peracarid crustaceans.

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Sex differences in foraging behaviour are typically studied in size-dimorphic taxa. Data on sex-specific behavior in monomorphic taxa are needed to test theories of reproductive investment. It has been suggested that in seabirds foraging niche separation may be related to decreased intersexual competition for food between cooperating pair-bonded individuals. Alternatively, sex differences in foraging niches may be driven by different nutritional requirements of females associated with the reproductive costs of egg production and oviposition. To assess these possibilities, we studied a size-monomorphic colonial seabird, the Australasian Gannet (Morus serrator) at the Cape Kidnappers gannetry, New Zealand. We recorded maximum dive depths, and distinct diet composition of incubating females as indicated by stable isotopic signatures. Results suggested greater female foraging effort during early times of incubation, indicated by significantly deeper maximum dives. Sex-specific foraging patterns across other breeding stages were more variable. Nitrogen stable isotopic values showed that incubating females occupied a different trophic position compared to males at the same breeding stage, and also from those of gannets of both sexes at later stages of parental care. Overall, the data are consistent with cost-of-oviposition compensation in females necessitating male-bias in parental care in biparental breeders. Further research is needed to unravel the implications for the evolution of sex differences in behavior in this and other monomorphic taxa.

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Two gadoid fishes, Arctogadus glacialis and Boreogadus saida, often coexist (i.e. sympatric) in the fjords and shelf areas of the Arctic seas, where they likely share the same food resources. Diet composition from stomach contents, i.e. frequency of occurrence (FO) and Schoener's index (SI), and stable isotope signatures (d13C and d15N) in muscle of these sympatric gadoids were examined from two fjords in NE Greenland-Tyrolerfjord (TF, ~74°N, sill present) and Dove Bugt (DB, ~76°N, open). Twenty-three prey taxa and categories were identified and both gadoids ate mostly crustaceans. The SI values of 0.64-0.70 indicated possible resource competition, whereas FO differed significantly. A. glacialis fed mainly on the mysid Mysis oculata and other benthic-associated prey, whereas B. saida ate the copepod Metridia longa and other pelagic prey. Both diet and stable isotopes strongly suggest a spatial segregation in feeding habitat, with A. glacialis being associated with the benthic food web (mean d13C = -20.81 per mil, d15N = 14.92 per mil) and B. saida with the pelagic food web (mean d13C = -21.25 per mil, d15N = 13.64 per mil). The dietary differences and isotopic signals were highly significant in the secluded TF and less clear in the open DB, where prey and predators may be readily advected from adjacent areas with other trophic conditions. This is the first study on the trophic position of A. glacialis inferred from analyses of stable isotopes. The subtle interaction between the Arctic gadoids should be carefully monitored in the light of ocean warming and ongoing invasions of boreal fishes into the Arctic seas.

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Studies on the fate of organohalogen contaminants (OHCs) in wild top predator mammals in the Arctic have often been a challenge due to important knowledge deficiencies in the life history of the sampled animals. The present study investigated the influence of age, dietary and trans-generational factors on the fate of major lipophilic chlorinated and brominated OHCs in adipose tissue of a potential surrogate captive species for the polar bear (Ursus maritimus), the sledge dog (Canis familiaris) in West Greenland. Adult female sledge dogs (P) and their sexually-mature (F1) and/or pre-weaning pups (F1-MLK) were divided into an exposed group (EXP) fed blubber from a Greenland minke whale (Balaenoptera acutorostrata) and a control group (CON) given commercially available pork fat. Large dietary treatment-related differences in summed and individual congener/compound adipose tissue concentrations of polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), chlordanes (CHLs) and polychlorinated biphenyls (PCBs) were found between the EXP and CON groups for all the sledge dog cohorts. However, among the F1-MLK, F1 and P dogs in both of the EXP and CON groups, little or no difference existed in PBDE, HCB, CHL and PCB concentrations, suggesting higher state of equilibrium in adipose tissue concentrations from a very early stage of life. In contrast, the distribution pattern (proportions to the summed concentrations) of OHC classes, and the major congeners/ compounds constituting those classes, varied on a dietary group- and/or cohort-dependent manner. The present captive sledge dog study demonstrated the importance of the confounding effects of diet composition, mother-pup association (maternal transfer), reproductive status (nursing), and to a lesser extent age in the fate of OHCs in adipose tissue of a large top carnivore mammal.

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Goose grazing on arctic tundra vegetation has shown both positive and negative effects on subsequent foraging conditions. To understand the potential of a density-dependent feedback on herbivore population size, the relation between grazing pressure and future foraging conditions is essential. We studied the effect of increasing grazing pressure of barnacle geese (Branta leucopsis) on Spitsbergen. During the establishment of a breeding colony in the period 1992-2004, the proportion of graminoids decreased in the diet of wild geese, while the percentage of mosses increased. Grazing trials with captive geese in an unexploited area showed a similar shift in diet composition. High-quality food plants were depleted within years and over years. Intake rate declined too and as consequence, metabolisable energy intake rate (MEIR) decreased rapidly with increasing grazing pressure. During three successive years of experimental grazing, MEIR decreased at all levels of grazing pressure and declined below minimal energetic requirements when grazing exceeded natural levels of grazing pressure. This suggests that foraging conditions rapidly decline with increasing grazing pressure in these low-productive habitats. The potential for density-dependent feedbacks on local population increase is discussed.

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Stable d13C and d15N isotopes, diet and parasites demonstrated that the prey consumed by ninespine stickleback Pungitius pungitius in a small lake on Baffin Island changed during the summer and also revealed intraspecific variation in their ecological niche. In July, there were differences in the diets of male and female ninespine stickleback as indicated by the stable isotopes, differences corroborated by the data on diet composition and the parasite fauna. Differences suggested that the sexes occupied different habitats during spawning. During July, females utilise the shallower littoral areas consuming zooplankton and benthic organisms, while males occupy deeper areas of the littoral zone feeding mainly on pelagic zooplankton. Parasite data support these observations as males had higher infections of copepod-transmitted parasites than females. There appeared to be no segregation of resources between males and females in late August, although the diet of both male and female ninespine stickleback shifted towards more benthic organisms, compared with July. Differences in d13C isotope, diet composition and infections of co-occurring parasites demonstrated that sympatric ninespine stickleback and Arctic char Salvelinus alpinus captured in the littoral zone occupied separate niches. Ninespine stickleback preyed mainly on zooplankton and chironomids, while Arctic char consumed a greater variety of prey items, including zooplankton and larger-sized prey such as insects and ninespine stickleback. The multifaceted approach improved our understanding of the trophic ecology of ninespine stickleback in southern Baffin Island and quantified resource use and dietary overlap with Arctic char.

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INTRODUCTION Young people with psychosis typically have higher rates of premature cardiovascular disease and metabolic disorders compared to non-psychotic peers. This has been primarily due to a sedentary lifestyle, poor diet composition, misuse of harmful substances and higher rates of obesity and smoking. When prescribed obesogenic antipsychotic medication, a weight gain of >12 kg within 2 years is typical. PURPOSE: To examine the benefits of a 12 wk exercise and lifestyle intervention entitled ‘Supporting Health and Promoting Exercise’ (SHAPE) for young people recently diagnosed with psychosis. METHODS Participants (n=26; 8 females; mean age 27.7 ± 5.1) engaged in weekly 45’ education sessions on healthy lifestyle behaviors, including: managing anxiety and depression, mindfulness and relaxation training, substance misuse, smoking cessation, healthy eating and nutritional advice, dental and sexual health care. This was followed by a 45’ exercise session including activities such as circuit and resistance training, yoga, and badminton, led by qualified exercise instructors. Anthropometric data were measured at baseline, 12 wk and 12 month post-intervention. Lifestyle behaviors and clinical measurements, including resting heart rate, blood pressure, total cholesterol, triglycerides, HbA1c and prolactin, were assessed at baseline and 12 months post-intervention as part of their routine clinical care plan. Significant differences over time were assessed using Paired Sample t-tests. RESULTS SHAPE participants (n=26) presented with first episode psychosis (n=11), schizophrenia (n=11), bipolar disorder (n=2), at risk mental state (n=1), and persistent delusion disorder (n=1) of which 52% were prescribed highly obesogenic antipsychotic medications (Clozapine and Olanzepine). Mean baseline data suggests participants were at an increased health risk due to elevated values in mean BMI (70% were overweight or obese), waist circumference, resting heart rate, and triglycerides (see Table 1 & 2). Over 50% reported smoking daily and 85% had elevated resting blood pressure (>120/80 mm Hg). At 12 wk post-intervention, no changes were observed in mean BMI or waist circumference (see Table 1); 19 participants either maintained (mean 0.5 kg: range ± 2 kg) or decreased (mean -5.7 kg: range 2-7 kg) weight; 7 participants increased weight (mean 4.9 kg: range 2.0-9.6 kg). At 12 month post-intervention (n=16), no change was evident in mean BMI, waist circumference, or any other clinical variable (see Table 2). Positive impacts on lifestyle behaviors included 7 participants eating ~400g of fruit/vegetables daily, 2 ceased substance use, 2 ceased alcohol use, 4 ceased smoking and 5 were less sedentary. CONCLUSION At the start of the programme, participants were already at an increased risk for cardiometabolic disorders. Findings suggest that SHAPE supported young people with psychosis to: -attenuate their physical health risk following a 12 wk exercise and lifestyle intervention which were sustained at 12 months follow up. -make positive lifestyle behavior changes leading to sustained improvements in weight maintenance and physical health.

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O golfinho-comum (Delphinus delphis) é uma das espécies de cetáceos mais abundantes e mais amplamente distribuídas em todo o planeta, sendo a espécie mais abundante ao longo da costa continental portuguesa. Algumas das suas principais presas apresentam um elevado interesse comercial estando por isso, muitas vezes, associado a capturas acidentais em artes de pesca. Contudo, estudos mais recentes sobre os hábitos alimentares desta espécie na costa portuguesa são escassos. Assim, este estudo visa contribuir para a avaliação da ecologia alimentar deste cetáceo na costa portuguesa através de índices de importância numérica, ocorrência e do peso estimado, permitindo descrever a dieta não só em termos qualitativos, mas também em termos quantitativos. Foram examinados os conteúdos estomacais de 55 golfinhoscomuns arrojados na costa continental portuguesa (norte e centro) entre 2004 e 2015. De um total de 6699 presas identificadas, 66% pertenciam à classe dos peixes, 32% eram cefalópodes e 3% eram crustáceos. As espécies-presa de peixes mais importantes em termos de importância numérica foram os góbios (Gobiidae) e o carapau (Trachurus sp.). Em relação à ocorrência foram o góbio (Gobiidae) e a sardinha (Sardina pilchardus), seguidas de carapau, as espécies predominantes. Relativamente ao peso, a sardinha foi a espécie-presa predominante, seguida de faneca (Trisopterus luscus) e carapau. Quanto aos cefalópodes, a lula-bicuda (Alloteuthis sp.) foi a espécie mais importante, tanto em termos de importância numérica como em termos de ocorrência. A lula-comum (Loligo sp.) foi a mais importante em termos de peso total estimado. As espécies demersais dominaram a dieta do golfinho-comum, com uma percentagem numérica de 40%. Foram detetadas diferenças entre machos e fêmeas na composição da dieta relativamente à sardinha. Foram detetadas diferenças entre indivíduos maturos e imaturos na composição da dieta relativamente à lula-bicuda. A diversidade de presas observada nos conteúdos estomacais do golfinho-comum sugere um comportamento oportunista, consumindo as presas mais abundantes, localmente. As interações com as artes de pesca podem levar a uma elevada mortalidade destes mamíferos marinhos. Deste modo, a realização de estudos sobre os hábitos alimentares de cetáceos permitem uma melhor compreensão das possíveis interações com a pesca, e a melhoria de estratégias de conservação para evitar a morte destes animais.

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Otoliths are calcified structures located in Osteichthyes’ inner ear that are involved in audition and balance. Their morphology is used as an indicator of various ecological processes or properties. This application requires identifying the endogenous and exogenous factors that act simultaneously as sources of shape variation. This thesis aims at detecting and quantifying the relative contributions of directional asymmetry and diet to otolith shape variation at the intra-population level. Directional asymmetry between left and right otoliths was found in flat-fishes, the blind-side otolith being always longer and larger, whereas it was negligible in round-fishes. However, asymmetry amplitude never exceeded 18 %, which suggests evolutionary canalization of otolith shape symmetry. A correlation between global diet and otolith was detected in 4 species studied in situ. Diet composition contributed more than food amount to morphological variation and affected otolith shape both globally and locally. An experimental study on sea bass (Dicentrarchus larbrax) showed that diet composition in terms of essential polyunsaturated fatty acids at larval stage affects otolith morphogenesis during juvenile stage without impacting on individuals’ somatic growth. This result suggests a direct effect of diet on otolith shape and not an indirect one through the somatic-otolith growth relationship. This effect disappeared at later stages, morphogenetic trajectories converging back to a similar shape, which suggests ontogenetic canalization of otolith shape.

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Dissertação de Mestrado Integrado em Medicina Veterinária

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The feeding habits of two major species of sole, the common sole Solea vulgaris Quensel, 1806 and the Senegalese sole Solea senegalensis Kaup, 1858 were studied in the lower estuary of the Guadiana River (Algarve, southern Portugal). An evaluation of the number, weight, and feeding coefficient of prey types showed that S. vulgaris feed on a limited variety of prey (only Polychaeta and Tanaidacea) and present low-intensity feeding activity, with small differences in diet between seasons. S. senegalensis also have a low-diversity diet (with only one more taxa, Amphipoda), but exhibit more intense feeding activity which varies seasonally, although with little seasonal variation in the relative importance of the main preys. The diet composition of these two species suggests feeding specialization.

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Changes in fish assemblage structure caused by human activities, such as fishing, can alter trophic relations in fish assemblages. In this context, Marine Protected Areas (MPA) are efficient tools for habitat recovery and ideal environments for evaluating changes on the trophic structure resulting from human activities. The present work targeted fish assemblages from two no-take MPAs from the northern half of South Alentejo and Costa Vicentina Marine Park, established in 2011. Previous works reported positive effects on local fish assemblages after no-take MPA designation, and it is therefore important to further study its impact on local fish assemblages, especially concerning trophic interactions. Local fish assemblages were sampled (summer 2011, winter 2012, summer 2013 and winter 2013) using trammel nets. Diets were characterized and digestive tract contents of the 10 most abundant fish species were compared between the no take MPAs (treatment) and adjacent areas (controls), and changes evaluated as a function of time since protection. Results revealed significant differences between the diets of fish from protected and non protected areas, with crabs being the preferential prey in both protected and control areas but being more ingested outside the no-take areas. However, these differences were evident since the beginning of the study. Fish assemblages from the northern area presented significantly larger niche breadth and significantly increasing with time. This way, the main effects of no-take MPA implementation were directly visible on the niche breadth but did not directly impact the diet composition of the sampled fish assemblages, contributing however to reinforce the already naturally existent differences. This work provides important information regarding the effect of changes in the fish assemblage caused by MPA designation on the trophic ecology of fish.

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From its domestication until nowadays, the horse has assumed multiple roles in human society. Over time, this condition and the lack of specific regulation have led to the development of different kinds of management systems for this species. This Ph.D. research project aims to investigate horses' welfare in different management practices and housing systems, considering a multidisciplinary approach, taking into account biological function, naturalness, and affective dimension. The results are presented in five articles that evidence risk factors that can mine horse welfare, and examine tools and parameters that can be employed for its assessment. Our research shows the importance of considering the evolutionary history and the species-specific and behavioural needs of horses in their management and housing. Sociality, free movement, diet composition and foraging routine, and the workload that these animals undergo are important factors that should be taken into account. Furthermore, this research has evidenced the importance of employing different parameters (e.g., behaviour, endocrinological parameters, and immune activity) in welfare assessment and proposes the use of horsehair DHEA (dehydroepiandrosterone) as a possible useful additional non-invasive measure for the investigation of long-term stress conditions. Finally, our results underline the importance of considering the affective dimension in welfare research. Recently, Judgement Bias Tests (JBT), which are based on the influence of affective states on the decision-making process, have been widely employed in animal welfare research. However, our studies show that the use of spatial JBT in horses can have some limitations. Still today several management systems do not fulfill species-specific needs of horses, thus the implementation of specific regulations could ameliorate horse welfare. A multidisciplinary approach to welfare assessment is fundamental, but it should be always remembered the individual and its own characteristics, which can influence not only physiological, immunological, and behavioural responses but also emotional and cognitive dimensions.