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This research investigated the effects of coordinating rodent control across areas up to 400 ha, using conventional and alternative strategies, to see if it was possible to reduce rat numbers and to keep them at a lower level compared with uncoordinated control. The aims were to reduce the rat numbers, reduce the amount of rodenticide used over time and to reduce the risk of secondary poisoning of non-target animals. Rodenticide loads in rat carcasses were investigated using historical and new samples from Berkshire, Leicestershire and Yorkshire in order to quantify risk to non-target predators of rats. Movement was also studied to see if rats were moving into farmyards in the autumn and out in the spring as is generally assumed. Analysis of radio-tracking data showed that the majority of rats tracked stayed within a small home range, two moved and stayed away from the trap site and only one moved into a farmyard. Analysis of the movement of the rats caught in traps showed that the movement towards and away from farms was in roughly equal numbers. The rodenticide analysis showed that rats from areas of rodenticide resistance carried a far greater body load of poison than those from non-resistance areas. Thus resistance increases the risk of a predator or scavenger of rats ingesting a lethal dose more quickly in areas of rodenticide resistance. The coordinated rat control was broadly successful over a period of two to three years. Rat numbers varied greatly between Yorkshire and Leicestershire, with Yorkshire having the larger numbers. Rat control in the coordinated areas showed a decreasing trend over the period. Bait take also generally showed a decline over the period. The results revealed an apparent delayed synchrony in rat numbers between coordinated and uncoordinated areas in Yorkshire that requires further investigation to explain.

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No description available.

No description available.

The sympatric occurrence of <i>M. edulis, Mytilus trossulus, Mytilus galloprovincialis </i>and their hybrids in cultivation has recently been reported and significant production losses attributed to the presence of <i>M. trossulus</i>. A molecular real-time PCR assay capable of identifying <i>M. edulis, M. trossulus </i>and <i>M. galloprovincialis </i>species-specific alleles was developed and applied to a large-scale survey of these species. We found <i>M. trossulus</i> distribution to be restricted to the south Highland and Argyll areas. Spawning asynchrony of <i>M. trossulus </i>and <i>M. edulis</i> was explored, aimed at favouring <i>M. edulis</i> production at mixed-species sites. However, the close similarity between these species and the impossibility of controlling important environmental and biological factors suggest strategies based on such differences would be too unpredictable for effective use by the industry. <i>M. trossulus </i>and its hybrids have also been noticed to be significantly more frequent on ropes in the upper 3-4 m of the water column, suggesting that changes in cultivation practices to avoid settlement in these depths are likely to reduce <i>M. trossulus</i> proliferation. At severely affected farms, the fallowing of sites and transfer of <i>M. edulis </i>unispecific seed is seen as the best long-term strategy towards the re-establishment of <i>M. edulis</i> stock. At all impacted farms area-specific solutions to managing the problem are being considered. Any management solutions will also be accompanied by an industry wide strategy and awareness, which will include the development of an industry supported code of good practice.

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The chemical aspects of the aerobic treatment of pig waste were investigated in farm scale systems associated with an intensive pig production unit. Changes in chemical composition were monitored over extended periods of aeration of liquid manure in oxidation ditches. Transformations of inorganic nitrogen in farm waste demonstrated considerable controlling influence over the mixed liquor pH and dissolved oxygen. Loss of soluble nitrogen (about 50% of the total nitrogen) appeared to be an inevitable consequence of aerobic treatment; the loss being sustained either by desorption of ammonia gas at high pH, or by nitrification and denitrification, which, may occur simultaneously even under apparently aerobic conditions. A two stage nitrification-denitrification sequence could eliminate almost all the soluble nitrogen from the mixed liquor. Incomplete nitrirication, as evidenced by nitrite and ammonium accumulation, resulted from the inhibition of nitrite oxidation by molecular ammonia and/or undissociated nitrous acid. This process, once initiated, became self-promoting. The chemical composition of farm waste slurries, mixed liquors and solids was investigated in detail. The partitioning of chemical species between solid and liquid phases was examined before and after treatment. Solids consisted of a mixture of coarse fibre and fine microbial sludge, the nitrogen and fibre contents being inversely related. The microbial solid contained 5 to 7% organic nitrogen most of which could be recovered as amino acids following hydrolysis. However methionine and isoleucine were found to be deficient. Mass balances in flow systems were analysed by a kinetic approach and an attempt was made to explain the inter-relationships between operating parameters.

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No description available.