The Effect of Diet on the Energy Budget of the Brown Sea Cucumber,Stichopus mollis (Hutton)     

Kimberley H. Maxwell  Jonathan P. A. Gardner  Philip L. Heath 《Journal of the World Aquaculture Society》2009,40(2):157-170

This study investigated the ability of the brown sea cucumber, Stichopus (Australostichopus) mollis, to grow on diets made from aquaculture waste. Weight‐standardized rates (ingestion, assimilation, respiration, ammonia excretion, and fecal excretion) of small (juvenile), medium (mature), and large (mature) sea cucumbers were measured and energy budgets constructed to quantify their growth rates when offered three different diets at 14, 16, and 18 C. Three types of diet were offered: uneaten abalone food (diet A) and two types of abalone feces, one where abalone were fed 50% Macrocystis pyrifera and 50% Undaria pinnatifida macroalgae (diet B) and the other where abalone were fed 25% M. pyrifera, 25% U. pinnatifida, and 50% Adam & Amos Abalone Food, where the latter is an industry standard diet (diet C). The organic contents of the diets were much higher than natural sediments and varied such that diet A (76.40%) > diet B (54.50%) > diet C (37.00%). Diet had a significant effect on S. mollis ingestion rates, assimilation efficiencies, and consequently energy budgets and growth rates. Greater quantities of organic matter (OM) from diet A and diet B were ingested and assimilated by the sea cucumbers compared with the OM in diet C. The energy budgets indicated that after taking routine metabolism into account, all sizes of sea cucumbers had energy to allocate to growth when offered diet A and diet B, but only juveniles had energy to allocate to growth when offered diet C. Fecal excretion rates when offered diet A and diet C at 14 C were greater than those at 18 C, but neither was significantly different from that at 16 C. Ammonia excretion rates increased nonlinearly with temperature for small and medium sea cucumbers but not for large sea cucumbers. Weight‐standardized respiration rates increased with temperature and unexpectedly with animal size, which may have been because of the narrow weight range of test animals biasing the results. These results suggest that industry standard type abalone waste lacks sufficient energy to meet the metabolic requirements of mature sea cucumbers but that growing juveniles on these wastes appears to be feasible and warrants further investigation.  相似文献   

With or without pheromone habituation: possible differences between insect orders?          下载免费PDF全文

David Maxwell Suckling  Lloyd D Stringer  Alfredo Jiménez‐Pérez  Gimme H Walter  Nicola Sullivan  Ashraf M El‐Sayed 《Pest management science》2018,74(6):1259-1264

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You cannot fight fire with fire: a demographic model suggests alternative approaches to manage multiple herbicide‐resistant Avena fatua          下载免费PDF全文

E E Burns  E A Lehnhoff  S C Mckenzie  B D Maxwell  W E Dyer  F D Menalled 《Weed Research》2018,58(5):357-368

Multiple herbicide‐resistant (MHR ) weed populations pose significant agronomic and economic threats and demand the development and implementation of ecologically based tactics for sustainable management. We investigated the influence of nitrogen fertiliser rate (56, 112, 168, or 224 kg N ha^?1) and spring wheat seeding density (67.3 kg ha^?1 or 101 kg ha^?1) on the demography of one herbicide susceptible and two MHR Avena fatua populations under two cropping systems (continuous cropping and crop‐fallow rotation). To represent a wide range of environmental conditions, data were obtained in field conditions over 3 years (2013–2015). A stochastic density‐dependent population dynamics model was constructed using the demographic data to project A. fatua populations. Elasticity analysis was used to identify demographic processes with negative impacts on population growth. In both cropping systems, MHR seedbank densities were negatively impacted by increasing nitrogen fertilisation rate and wheat density. Overall, MHR seedbank densities were larger in the wheat‐ fallow compared with the continuous wheat cropping system and seedbank densities stabilised near zero in the high nitrogen and high spring wheat seeding rate treatment. In both cropping systems, density‐dependent seed production was the most influential parameter impacting population growth rate. This study demonstrated that while the short‐term impact of weed management tactics can be investigated by field experiments, evaluation of long‐term consequences requires the use of population dynamics models. Demographic models, such as the one constructed here, will aid in selecting ecologically based weed management tactics, such as appropriate resource availability and modification to crop competitive ability to reduce the impact of MHR .  相似文献   

Use of antiviral medications against equine herpes virus associated disorders     

D. M. Wong  L. K. Maxwell  P. A. Wilkins 《Equine Veterinary Education》2010,22(5):244-252

Numerous types of equine herpesviruses (EHV) continue to afflict horses resulting in a variety of clinical manifestations. While many of the clinical manifestations of EHV are self‐limiting or require only supportive care, some clinical expressions of EHV infections cause severe risk to the horse's overall health and can result in abortion, long‐term deficits or death. Antiviral medications are infrequently utilised therapeutics in equine medicine and their exact efficacy is largely unknown. However, the use of antiviral medications may potentially decrease convalescent time and improve outcome in horses with EHV‐related diseases. Thus, equine practitioners should consider the potential use of antiviral medications in the future. The purpose of this article is to familiarise the equine practitioner with current information in regard to antiviral medications and their potential uses in equine medicine.  相似文献   

Signal detection theory clarifies the concept of perceptual range and its relevance to landscape connectivity     

Robert J. Fletcher Jr.  Christopher W. Maxwell Jr.  John E. Andrews  Wendy L. Helmey-Hartman 《Landscape Ecology》2013,28(1):57-67

Understanding functional connectivity is critical for several issues in ecology and conservation. When animals actively search for habitat across landscapes, their perceptual range of habitats can profoundly influence connectivity. Nonetheless, conceptual development and estimation of perceptual ranges and their influence on connectivity have been limited. Signal detection theory (SDT) has a long tradition in several disciplines to address the problem of detecting stimuli in noisy and uncertain environments. SDT is particularly useful for understanding perceptual ranges because it acknowledges uncertainty in the detection process and distinguishes between two key parameters that have previously been confounded when interpreting the perceptual range of animals: signal detectability and response bias of individuals. Here we extend SDT to the concept of perceptual range, provide approaches for estimating patch detectability and response bias, and apply this framework to interpreting the perceptual range of cactus bugs (Chelinidea vittiger). We find that signal detectability of habitat by C. vittiger, and thus their perceptual range, is between 1 and 2 m, based on generalized linear models aimed at estimating signal detection parameters. SDT provides new insights into perceptual ranges and functional connectivity, which may help understand intra and interspecific variation in animal responses to modified landscapes.  相似文献   

Terraclor (PCNB) for control ofRhizoctonia solani. II. PCNB residues in tubers     

G. D. Easton  R. C. Maxwell  C. R. Oldenburg  P. D. Anderson 《American Journal of Potato Research》1970,47(11):430-434

Terraclor (PCNB) applied to soils by broadcast and row slightly reduced the incidence ofRhizoctonia solani but did not increase yield or per cent of U. S. No. 1 tubers either by weight or numbers. Residues of PCNB in tubers grown in treated soils increased as the rate per acre of PCNB increased. Almost all of the residues were in the tuber peel.  相似文献   

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK. 5. The effect of stocking rate and reduced levels of nitrogen fertilizer     

A. R. Sibbald  T. J. Maxwell  A. J. I. Dalziel  & R. D. M. Agnew 《Grass and Forage Science》2002,57(1):33-47

The implications for UK upland sheep systems of reducing nitrogen fertilizer application to perennial ryegrass/white clover swards were studied over 3 years. Sward height (3·5–5·5 cm) was controlled for ewes with lambs until weaning using surplus pasture areas for silage; thereafter, ewes and weaned lambs were grazed on separate areas, and sward height was controlled by adjusting the size of the areas grazed and using surplus pasture areas for silage if necessary. Combinations from three stocking rates [10, 6 and 4 ewes ha⁻¹ on the total area (grazed and ensiled)] and four nitrogen fertilizer levels (150, 100, 50 and 0 kg ha⁻¹) provided six treatments that were replicated three times. Average white clover content was negatively correlated with level of nitrogen fertilizer. The proportion of white clover in the swards increased over the duration of the experiment. Control of sward height and the contribution from white clover resulted in similar levels of lamb liveweight gain on all treatments. All treatments provided adequate winter fodder as silage. It is concluded that the application of nitrogen fertilizer can be reduced or removed from upland sheep pastures without compromising individual animal performance provided that white clover content and sward height are maintained. Resting pastures from grazing by changing ensiled and grazed areas from year to year sustained white clover content over a 3-year period.  相似文献   

Incidence and new records of Mycosphaerella species within a Eucalyptus globulus plantation in Western Australia     

S.L. Jackson  A. Maxwell  T.I. Burgess  G.E.StJ. Hardy  B. Dell   《Forest Ecology and Management》2008,255(12):3931-3937

Eucalyptus globulus is the predominant exotic hardwood plantation species in Western Australian (WA), and is often planted adjacent to native eucalypt forests. The increase in number of Mycosphaerella species associated with Mycosphaerella leaf disease (MLD) in E. globulus plantations in WA in the past decade has raised concern about the possible movement of pathogens between the native forests and plantations. In order to determine whether the introduction of new E. globulus genetics into WA may have further exacerbated this situation, juvenile and adult foliage were taken from a genetics trial near Albany, WA consisting of 60 full-sib families and Mycosphaerella species identified using morphological and molecular tools. Eleven species of Mycosphaerella were identified from one plantation: Mycosphaerella fori (Pseudocercospora fori) and Mycosphaerella ellipsoidea are new records for Australia; Mycosphaerella tasmaniensis (Passalora tasmaniensis) and Mycosphaerella suttoniae (Kirramyces epicoccoides) are new records for WA; and Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella marksii, Mycosphaerella molleriana, Mycosphaerella lateralis, Mycosphaerella aurantia and Mycosphaerella parva, previously recorded for WA. The most frequently isolated species from juvenile foliage was M. marksii (77%) followed by M. nubilosa (33%). M. nubilosa was most frequently isolated from adult leaves (88%) followed by M. parva (7.5%). Three species, M. molleriana, M. lateralis and M. cryptica, were only isolated from adult leaves while M. ellipsoidea was only isolated from juvenile leaves. These records increase the number of known Mycosphaerella species from eucalypts in WA from 10 to 13. The increase in the number, distribution and impact of Mycosphaerella species contributing to MLD in WA is of concern both to the potential productivity of the plantations and the biosecurity of native WA Eucalyptus species. Continued monitoring of the plantation estate is required to understand the dynamics of the host–pathogen interactions.  相似文献   

Assessment of Genetic Diversity for Grain Yield and Yield Component Traits in Some Genotypes of Rice (Oryza Sativa L.)     

Asante  Maxwell Darko  Adjah  Kossi Lorimpo  Annan-Afful  Ebenezer 《Journal of Crop Science and Biotechnology》2019,22(2):123-130

Journal of Crop Science and Biotechnology - Even though there are abundant rice genetic resources, only a fraction is used in breeding programs leading to a narrow genetic base for improved...  相似文献   

Ultrastructural and cytochemical studies in normal Japanese quail (Coturnix coturnix japonica) eosinophils and in those from birds with experimentally induced eosinophilia     

M H Maxwell 《Research in veterinary science》1986,41(2):149-161

Normal eosinophil development in the Japanese quail (Coturnix coturnix japonica) was similar to that described in the fowl and the duck, with granulogenesis occurring in the Golgi apparatus. The characteristic lipid droplets were small in the immature eosinophils, and after staining specifically for lipid, small moieties were also traced to the Golgi apparatus. In mature eosinophils the lipid droplets measured between 1.0 and 1.5 micron in diameter and they were surrounded by profiles of smooth endoplasmic reticulum. Eosinophilia was difficult to induce in quails; injections of either horse serum or bovine serum albumin (BSA)/aluminium hydroxide produced a poor response. In some quails in which eosinophilia was produced, however, eosinophil granules showed many crescentic and vacuolated forms. The lipid droplets in the activated eosinophils were fused in many cells to form large intracellular aggregates of lipid. Quail eosinophils, which hitherto have been regarded as peroxidase-negative, had strong activity in the lipid droplets of cells from stimulated birds. It is postulated that this peroxidase-positive reaction may represent a form of ceroid or lipofuscin pigment resulting from lipid peroxidation. Acid phosphatase and trimetaphosphatase reactions were reduced in many activated cells, with a large proportion of granules being non-reactive. The results of dietary manipulations in quails appear to suggest that in stressful situations the eosinophil metabolism is altered and there is a reduction in the number of lipid droplets in the cell.  相似文献