Grassland Management and Animal Product Quality

The expectations of consumers ultimately determine the specification of product quality; and grassland systems produce a wide range of animal-based products. Therefore, to provide focus, this paper deals only with food products that are destined for markets that exhibit strong discretionary choice. Quality expectations of consumers have traditionally been based on product attributes such as taste, freshness, nutritional value and appearance, but customer expectations are expanding to encompass food safety, environmental care, animal welfare and biotechnologies. Grassland forages and their management influence the intrinsic sensory properties of food. A dairy products case study is presented, indicating that pasture species and their interaction with local environmental factors, and the methods of forage conservation, can influence the chemical composition of milk, its ability to be processed into butter or cheese, and the final sensory characteristics of the product. These effects may result directly from compounds originating in the forage (e.g. carotenoids, aromatic terpenes) or indirectly through forage-related changes in animal physiology and enzyme production. Knowledge of these influences and the strict control of the determining factors are key elements in the granting of Protected Denomination of Origin (DMO) status and the benefits that accrue from marketing strategies that depend on this status. Animal feeding regimes also influence the attributes of meat. Pasture-grazed animals have harder and yellower carcass fat than grain-fed animals. The daily energy intake of pasture-grazed animals is also generally lower; therefore there is less intra-muscular marbling. In addition, glycogen levels tend to be more marginal, which can negatively interact with psychological stress to produce a greater incidence of high ultimate pH carcasses. High pH levels (\u3e 5.8) result in reduced tenderness, dark muscle and reduced shelf-life of fresh and chilled meats. Early identification of product quality variation is key to placing meat into the correct supply chain, and maximising the total value of the carcass. The positive and negative aspects of fatty acid profiles, phenol and indole compounds, and antioxidants originating from forages are discussed in respect of meat flavour and animal health. Tight planning and management protocols for both plants and animals are crucial to achieving quality raw material from grassland systems. Unlike feedlot and barn-based enterprises, variation in forage quantity and quality can severely impact on animal performance, timeliness of supply and raw product constituents. Control of a forage-based system requires the setting of performance targets and on-going monitoring. Such measures can signal when the tactical use of specialist forages, or of high-quality supplements, will be of most value in maintaining target performance and animal health. Consistently supplying products with desired attributes, attending to animal welfare expectations and caring for environmental integrity will all be required if the credibility of ‘natural’ grassland products is to be sustained in the market-place. Controlled grazing of animals will be invaluable in meeting these multiple market demands

Large-Area Graphene-Based Nanofiltration Membranes by Shear Alignment of Discotic Nematic Liquid Crystals of Graphene Oxide

Graphene-based membranes demonstrating ultrafast water transport, precise molecular sieving of gas and solvated molecules shows great promise as novel separation platforms; however, scale-up of these membranes to large-areas remains an unresolved problem. Here we demonstrate that the discotic nematic phase of graphene oxide (GO) can be shear aligned to form highly ordered, continuous, thin films of multi-layered GO on a support membrane by an industrially adaptable method to produce large-area membranes (13 × 14 cm2) in \u3c 5 s. Pressure driven transport data demonstrate high retention (\u3e 90%) for charged and uncharged organic probe molecules with a hydrated radius above 5 Å as well as modest (30–40%) retention of monovalent and divalent salts. The highly ordered graphene sheets in the plane of the membrane make organized channels and enhance the permeability (71±5 l m−2 hr−1 bar−1 for 150±15 nm thick membranes)

The consequences of reservoir host eradication on disease epidemiology in animal communities.

Non-native species have often been linked with introduction of novel pathogens that spill over into native communities, and the amplification of the prevalence of native parasites. In the case of introduced generalist pathogens, their disease epidemiology in the extant communities remains poorly understood. Here, Sphaerothecum destruens, a generalist fungal-like fish pathogen with bi-modal transmission (direct and environmental) was used to characterise the biological drivers responsible for disease emergence in temperate fish communities. A range of biotic factors relating to both the pathogen and the surrounding host communities were used in a novel susceptible-exposed-infectious-recovered (SEIR) model to test how these factors affected disease epidemiology. These included: (i) pathogen prevalence in an introduced reservoir host (Pseudorasbora parva); (ii) the impact of reservoir host eradication and its timing and (iii) the density of potential hosts in surrounding communities and their connectedness. These were modelled across 23 combinations and indicated that the spill-over of pathogen propagules via environmental transmission resulted in rapid establishment in adjacent fish communities (<1 year). Although disease dynamics were initially driven by environmental transmission in these communities, once sufficient numbers of native hosts were infected, the disease dynamics were driven by intra-species transmission. Subsequent eradication of the introduced host, irrespective of its timing (after one, two or three years), had limited impact on the long-term disease dynamics among local fish communities. These outputs reinforced the importance of rapid detection and eradication of non-native species, in particular when such species are identified as healthy reservoirs of a generalist pathogen

Benthic algal response to N and P enrichment along a pH gradient

Nutrient enrichment and its effect on benthic algal growth, community composition, and average cell size was assessed across two sites of differing pH within a single habitat. Nutrients were added using in situ substrata, which released either N, P, or no additional nutrients (controls) at each site for 21 days. Upon collection, chlorophyll and biovolume standing stocks of the attached algal microflora were measured. Chlorophyll concentration was different among all treatments, accumulating greatest on P, followed by N, and the least on C substrata (P < 0.001) and was highest at site-2 (P < 0.001), while total algal biovolume was highest on P compared to both N and C substrata (P < 0.05) and did not vary between sites. Increased growth on P substrata was due to the enhanced biovolume of filamentous green algae, although the affected taxa varied between sites. Biovolume to cell density ratios (as a measure of average cell size) were highest on P substrata over both N-enriched and control substrata (P < 0.05) and this pattern was similar between sites. Progression towards a community composed of larger cells following P enrichment observed along this pH gradient, seems to be related to the dominance of larger celled filamentous green algae. Thus, nutrients exhibited greater control on benthic algal growth than did changes in hydrogen ion concentration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42877/1/10750_2004_Article_BF00007599.pd