Resource allocation in two species systems: Is it worth acknowledging species interactions?

It is becoming increasingly popular to consider species interactions when managing ecological foodwebs. Such an approach is useful in determining how management can affect multiple species, with either beneficial or detrimental consequences. Identifying such actions is particularly valuable in the context of conservation decision making as funding is severely limited. This paper outlines a new approach that simplifies the resource allocation problem in a two species system for a range of species interactions: independent, mutualism, predator-prey, and competitive exclusion. We assume that both species are endangered and we do not account for decisions over time. We find that optimal funding allocation is to the conservation of the species with the highest marginal gain in expected probability of survival and that, across all except mutualist interaction types, optimal conservation funding allocation differs between species. Loss in efficiency from ignoring species interactions was most severe in predator-prey systems. The funding problem we address, where an ecosystem includes multiple threatened species, will only become more commonplace as increasing numbers of species worldwide become threatened. © 2011 Elsevier B.V.

Polyacrylic Acid Assisted Synthesis of Cu2ZnSnS4 by Hydrothermal Method

Pure phase Cu2ZnSnS4 (CZTS) nanoparticles were successfully synthesized via polyacrylic acid (PAA) assisted one-pot hydrothermal route. The morphology, crystal structure, composition and optical properties as well as the photoactivity of the as-synthesized CZTS nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrometer, UV-visible absorption spectroscopy and photoelectrochemical measurement. The influence of various synthetic conditions, such as the reaction temperature, reaction duration and the amount of PAA in the precursor solution on the formation of CZTS compound was systematically investigated. The results have shown that the crystal phase, morphology and particle size of CZTS can be tailored by controlling the reaction conditions. The formation mechanism of CZTS in the hydrothermal reaction has been proposed based on the investigation of time-dependent phase evolution of CZTS which showed that metal sulfides (e.g., Cu2S, SnS2 and ZnS) were formed firstly during the hydrothermal reaction before forming CZTS compound through nucleation. The band gap of the as-synthesized CZTS nanoparticles is 1.49 eV. The thin film electrode based on the synthesized CZTS nanoparticles in a three-electrode photoelectrochemical cell generated pronounced photocurrent under illumination provided by a red light-emitting diode (LED, 627 nm), indicating the photoactivity of the semiconductor material.

Click functionalization of methacrylate-based hydrogels and their cellular response

Methacrylate-based hydrogels, such as homo- and copolymers of 2-hydroxyethyl methacrylate (HEMA), have demonstrated significant potential for use in biomedical applications. However, many of these hydrogels tend to resist cell attachment and growth at their surfaces, which can be detrimental for certain applications. In this article, glycidyl methacrylate (GMA) was copolymerized with HEMA to generate gels functionalized with epoxide groups. The epoxides were then functionalized by two sequential click reactions, namely, nucleophilic ring opening of epoxides with sodium azide and then coupling of small molecules and peptides via Huisgen's copper catalyzed 1,3-dipolar cycloaddition of azides with alkynes. Using this strategy it was possible to control the degree of functionalization by controlling the feed ratio of monomers during polymerization. In vitro cell culture of human retinal pigment epithelial cell line (ARPE-19) with the hydrogels showed improved cell adhesion, growth and proliferation for hydrogels that were functionalized with a peptide containing the RGD sequence. In addition, the cell attachment progressively decreased with increasing densities of the RGD containing peptide. In summary, a facile methodology has been presented that gives rise to hydrogels with controlled degrees of functionality, such that the cell response is directly related to the levels and nature of that functionality.

Evaluation of existing and new insecticides including spirotetramat and pyridalyl to control Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on peppers in Queensland.

Insecticides are used by growers to control Frankliniella occidentalis (western flower thrips) in Australian vegetable crops. However, limited information was available on the efficacy of some insecticides used against F. occidentalis and data on new insecticides that could be included in a resistance management program were required. The efficacy of 16 insecticides in controlling F. occidentalis was tested in four small plot trials in chillies and capsicums. Spinosad, fipronil and methamidophos were effective against adults and larvae. Spirotetramat had no efficacy against adults but was very effective against larvae. Pyridalyl was moderately effective against larvae. Methidathion showed limited effectiveness. Abamectin, amorphous silica, bifenthrin, chlorpyrifos, dimethoate, emamectin benzoate, endosulfan, imidacloprid, methomyl and insecticidal soap were not effective. Laboratory bioassays on F. occidentalis collected from the field trials showed resistance to bifenthrin but not to the other insecticides tested. The trials demonstrated that some insecticides permitted for use against F. occidentalis are not effective and identified a number of insecticides, including the new ones spirotetramat and pyridalyl, that are effective and that could be used to manage the pest within a resistance management program.

Concentrate feeding strategies for growing and finishing dairy bulls offered grass silage-based diets

The first aim of this thesis was to produce data for evaluating, developing and recommending biologically and economically efficient energy and protein feeding strategies for growing and finishing dairy bulls offered grass silage-based diets. The second aim was to calculate the energy and protein supplies of the dairy bulls fed different grass silage-cereal-based diets and, based on this, to estimate the possible need to revise the current Finnish energy and protein recommendations for growing dairy bulls. The third aim was to demonstrate the phosphorus supply of dairy bulls fed grass silage-cereal-based diets with or without protein supplementation in relation to current feeding recommendations for phosphorus. The results indicate that protein supplement is not needed for finishing dairy bulls (live weight more than 250 kg) when they are fed good-quality grass silage (digestible organic matter more than 650 g/kg dry matter, restricted fermentation with low concentrations of fermentation acids and ammonia N) and grain-based concentrate with a moderate (300-700 g/kg dry matter) concentrate level. The results also suggest that with total mixed ration feeding it is possible to use rather high concentrate proportions (700 g/kg dry matter) in feeding dairy bulls. According to this study, barley fibre is a suitable energy supplement with good-quality silage for growing dairy bulls. The results suggest that 50% of barley grain can be replaced with barley fibre without affecting growth. Also oats is a suitable energy supplement for dairy bulls. However, as a consequence of decreased energy intake, the gain and feed conversion of the bulls were slightly reduced in this study when barley grain was replaced by oats in the diet. Ultimately, the rationality of the use of barley fibre and oats in the future will depend on the price in relation to other concentrates. During the feeding experiments the calculated supply of energy was 10% higher than in the Finnish feeding recommendations for the present growth rate. This indicates that there is a need to update the Finnish feeding recommendations for dairy-breed growing bulls, and further calculations are needed for the energy supply of growing dairy bulls. The calculated supply of AAT (amino acids absorbed from the small intestine) was 38% higher than in the Finnish feeding recommendations for the present growth. Possibly, the present AAT-PBV system is not an optimal protein evaluation system for growing dairy bulls more than 250 kg live weight. The calculations based on the feeding experiments and the Finnish feeding recommendations indicate that in most cases the dairy bulls (live weight more than 250 kg) received enough P from the basic grass silage cereal-based diets without additional mineral feeds. Therefore there is no need to add P in the form of mineral mixtures.

Egg production in furnished cages

In the European Union, conventional cages for laying hens will be faded out at the beginning of 2012. The rationale behind this is a public concern over animal welfare in egg production. As alternatives to conventional cages, the European Union Council Directive 1999/74/EC allows non-cage systems and enriched (furnished) cages. Layer performance, behavior, and welfare in differently sized furnished cages have been investigated quite widely during recent decades, but nutrition of hens in this production system has received less attention. This thesis aims to compare production and feed intake of laying hens in furnished and conventional cages and to study the effects of different dietary treatments in these production systems, thus contributing to the general knowledge of furnished cages as an egg production system. A furnished cage model for 8 hens was compared with a 3-hen conventional cage. Three consecutive experiments each studied one aspect of layer diet: The first experiment investigated the effects of dietary protein/energy ratio, the second dietary energy levels, and the third the effects of extra limestone supplementation. In addition, a fourth experiment evaluated the effects of perches on feed consumption and behavior of hens in furnished cages. The dietary treatments in experiments 1 3 generally had similar effects in the two cage types. Thus, there was no evidence supporting a change in nutrient requirements for laying hens when conventional cages are replaced with small-group furnished cages. Moreover, the results from nutritional experiments conducted in conventional cages can be applied to small-group furnished cage systems. These results support the view that production performance comparable with conventional cages can be achieved in furnished cages. All of the advantages of cages for bird welfare are sustained in the small-group furnished cages used here. In addition, frequent use of perches and nests implies a wider behavioral repertoire in furnished cages than in conventional cages. The increase observed in bone ash content may improve bird welfare in furnished cages. The presence of perches diminished feed consumption during the prelaying period and enhanced the feed conversion ratio during the early laying period in furnished cages. However, as the presence or absence of perches in furnished cages had no significant effect on feed consumption after the prelaying period, the lower feed consumption observed in furnished cages than in conventional cages could be attributed to other factors, such as the presence of wood shavings or a nest box. The wider feed trough space per hen in conventional than in furnished cages may partly explain the higher feed consumption observed in conventional cages.

Influence of harvesting strategy on nutrient supply and production of dairy cows consuming diets based on grass and red clover silage

The main objective of this thesis was to elucidate the effects of regrowth grass silage and red clover silage on nutrient supply and milk production of dairy cows as compared with primary growth grass silages. In the first experiment (publication I), two primary growth and four regrowth grass silages were harvested at two stages of growth. These six silages were fed to 24 lactating dairy cows with two levels of concentrate allowance. Silage intake and energy corrected milk yield (ECM) responses, and the range in these response variables between the diets, were smaller when regrowth silages rather than primary growth silages were fed. Milk production of dairy cows reflected the intake of metabolizable energy (ME), and no differences in the ME utilization were found between the diets based on silages harvested from primary growth and regrowth. The ECM response to increased concentrate allowance was, on average, greater when regrowth rather than primary growth silages were fed. In the second experiment (publication II), two silages from primary growth and two from regrowth used in I were fed to rumen cannulated lactating dairy cows. Cows consumed less feed dry matter (DM), energy and protein, and produced less milk, when fed diets based on regrowth silages rather than primary growth silages. Lower milk production responses of regrowth grass silage diets were mainly due to the lower silage DM intake, and could not be accounted for by differences in energy or protein utilization. Regrowth grass silage intake was not limited due to neutral detergent fibre (NDF) digestion or rumen fill or passage kinetics. However, lower intake may be at least partly attributable to plant diseases such as leaf spot infections, dead deteriorating material or abundance of weeds, which are all higher in regrowth compared with primary growth, and increase with advancing regrowth. In the third experiment (publications III and IV), red clover silages and grass silages harvested at two stages of growth, and a mixed diet of red clover and grass silages, were fed to five rumen cannulated lactating dairy cows. In spite of the lower average ME intake for red clover diets, the ECM production remained unchanged suggesting more efficient utilisation of ME for red clover diets compared with grass diets. Intake of N, and omasal canal flows of total non-ammonia N (NAN), microbial and non-microbial NAN were higher for red clover than for grass silage diets, but were not affected by forage maturity. Delaying the harvest tended to decrease DM intake of grass silage and increase that of red clover silage. The digestion rate of potentially digestible NDF was faster for red clover diets than for grass silage diets. Delaying the harvest decreased the digestion rate for grass but increased it for red clover silage diets. The low intake of early-cut red clover silage could not be explained by silage digestibility, fermentation quality, or rumen fill but was most likely related to the nutritionally suboptimal diet composition because inclusion of moderate quality grass silage in mixed diet increased silage DM intake. Despite the higher total amino acid supply of cows fed red clover versus grass silage diets, further milk production responses on red clover diets were possibly compromised by an inadequate supply of methionine as evidenced by lower methionine concentration in the amino acid profile of omasal digesta and plasma. Increasing the maturity of ensiled red clover does not seem to affect silage DM intake as consistently as that of grasses. The efficiency of N utilization for milk protein synthesis was lower for red clover diets than for grass diets. It was negatively related to diet crude protein concentration similarly to grass silage diets.

Undersowing in a northern climate: effects on spring cereal yield and risk of nitrate leaching

Disadvantages of invariable cereal cropping, concern of nutrient leaching and prices of nitrogen (N) fertilizer have all increased during last decades. An undersown crop, which grows together with a main crop and after harvest, could mitigate all those questions. The aim of this study was to develop undersowing in Finnish conditions, so that it suits for spring cereal farming as well as possible and enhances taking care of soil and environment, especially when control of N is concerned. In total, 17 plant species were undersown in spring cereals during the field experiments between 1991-1999 at four sites in South and Central Finland, but after selection, eight of them were studied more thoroughly. Two legumes, one grass species and one mixture of them were included in long-term trials in order to study annually repeated undersowing. Further, simultaneous broadcasting of seeds instead of separate undersowing was studied. Grain yield response and the capacity of the undersown crop to absorb soil N or fix N from atmosphere, and the release of N were of greatest interest. Seeding rates of undersown crops and N fertilization rates during annually repeated undersowing were also studied. Italian ryegrass (Lolium multiflorum Lam., IR) absorbed soil nitrate N (NO3-N) most efficiently in autumn and timothy (Phleum pratense L.) in spring. The capacity of other grass species to absorb N was low, or it was insufficient considering the negative effect on grain yield. Red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) suited well in annually repeated undersowing, supplying fixed N for cereals without markedly increased risk of N leaching. Autumn oriented growth rhythm of the studied legumes was optimal for undersowing, whereas the growth rhythm of grasses was less suited but varied between species. A model of adaptive undersowing system was outlined in order to emphasize allocation of measures according needs. After defining the goal of undersowing, many decisions are to be done. When diminishing N leaching is primarily sought, a mixture of IR and timothy is advantageous. Clovers suit for replacing N fertilization, as the positive residual effect is greater than the negative effect caused by competition. A mixture of legume and non legume is a good choice when increased diversity is the main target. Seeding rate is an efficient means for adjusting competition and N effects. Broadcasting with soil covering equipment can be used to establish an undersown crop. In addition, timing and method of cover crop termination have an important role in the outcome. Continuous observing of the system is needed as for instance conditions significantly affect growth of undersown crop and on the other hand N release from crop residues may increase in long run.

Land leasing, land degradation and agricultural productivity in Finland

This study analysed whether the land tenure insecurity problem has led to a decline in long-term land improvements (liming and phosphorus fertilization) under the Common Agricultural Policy (CAP) and Nordic production conditions in European Union (EU) countries such as Finland. The results suggests that under traditional cash lease contracts, which are encouraged by the existing land leasing regulations and agricultural subsidy programs, the land tenure insecurity problem on leased land reduces land improvements that have a long pay-back period. In particular, soil pH was found to be significantly lower on land cultivated under a lease contract compared to land owned by the farmers themselves. The results also indicate that land improvements could not be reversed by land markets, because land owners would otherwise have carried out land improvements even if not farming by themselves. To reveal the causality between land tenure and land improvements, the dynamic optimisation problem was solved by a stochastic dynamic programming routine with known parameters for one-period returns and transition equations. The model parameters represented Finnish soil quality and production conditions. The decision rules were solved for alternative likelihood scenarios over the continuation of the fixed-term lease contract. The results suggest that as the probability of non-renewal of the lease contract increases, farmers quickly reduce investments in irreversible land improvements and, thereafter, yields gradually decline. The simulations highlighted the observed trends of a decline in land improvements on land parcels that are cultivated under lease contracts. Land tenure has resulted in the neglect of land improvement in Finland. This study aimed to analyze whether these challenges could be resolved by a tax policy that encourages land sales. Using Finnish data, real estate tax and a temporal relaxation on the taxation of capital gains showed some potential for the restructuring of land ownership. Potential sellers who could not be revealed by traditional logit models were identified with the latent class approach. Those landowners with an intention to sell even without a policy change were sensitive to temporal relaxation in the taxation of capital gains. In the long term, productivity and especially productivity growth are necessary conditions for the survival of farms and the food industry in Finland. Technical progress was found to drive the increase in productivity. The scale had only a moderate effect and for the whole study period (1976–2006) the effect was close to zero. Total factor productivity (TFP) increased, depending on the model, by 0.6–1.7% per year. The results demonstrated that the increase in productivity was hindered by the policy changes introduced in 1995. It is also evidenced that the increase in land leasing is connected to these policy changes. Land institutions and land tenure questions are essential in agricultural and rural policies on all levels, from local to international. Land ownership and land titles are commonly tied to fundamental political, economic and social questions. A fair resolution calls for innovative and new solutions both on national and international levels. However, this seems to be a problem when considering the application of EU regulations to member states inheriting divergent landownership structures and farming cultures. The contribution of this study is in describing the consequences of fitting EU agricultural policy to Finnish agricultural land tenure conditions and heritage.