The effect of high broiler litter diets as survival ration on the health of sheep

The use of broiler litter as an emergency feed during droughts and other periods of feed shortages was evaluated in terms of its effect on the health of sheep. Pure broiler litter (i.e. excreta plus wood shavings), and litter mixed with 7.5 or 15 % molasses were fed for 83 days to 2-year-old wethers. The addition of molasses to the litter caused a significant increase (p < 0.01) in feed intake and final body mass. Various parameters such as plasma enzyme activity, plasma metabolite concentrations and urine mineral and purine excretion did not differ among treatments. Histological evaluation revealed no liver or kidney pathology. Mild myocardial pathology was observed in all 3 treatment groups. This seems to be related to the presence of the ionophore-based coccidiostat, narasin, which was present in the litter at a concentration of 10 mg/kg. It is suggested that these histological lesions are of little practical significance and would not affect the health of sheep being fed the broiler litter as a survival feed

The impact of the Scheldt input on the trace metal distribution in the Belgian coastal area (results of 1981-1983 and 1995-1996)

Offshore fluxes of Cu, Zn, Cd, Pb and Hg were calculated based on residual flow patterns and salinity gradients along the Belgian coast. The residual flow lines along the Belgian coast are more or less parallel to the coast except the area where the north-easterly flowing water mass coming from the Channel encounters the south-westerly-oriented Scheldt outflow, forming a residual hydrodynamical front. From the steady-state salinity pattern, diffusion coefficients perpendicular to the residual flow were deduced; they ranged from 21 to 108 m² s-¹ . Offshore fluxes of dissolved and particulate trace metals based on diffusive and mixing processes are calculated. The steady state profiles of dissolved metals show a dilution effect in the coastal waters, reaching an almost constant concentration in the marine water mass in the 1981-1983 dataset. The ratios of the Scheldt input of trace metals to the total dissolved offshore flux vary from 38 to 55% (1981-1983), depending on the kind of metal, and from 5 to 91 % (1995-1996). The ratio of the Scheldt input to the dissolved metal flow parallel to the coast, is in both periods (1981-1983 and 1995-1996), smaller than 1 %. The steady-state concentration profiles of particular metals versus salinity are fairly constant in the coastal-estuarine and marine water masses, but decrease very abruptly from the first to the second water mass. Assuming a conservative behaviour of the particular metals, offshore fluxes and the resulting concentration increases agree fairly well with the observed values. The ratios of the Scheldt input to the particulate trace metal offshore flux vary between 30 to 46% (1981-1983) and 13 to 37% (1995-1996). The contribution of the Scheldt estuary to the flows parallel to the coast ranges from 1.6 to 2.9% (1981-1983) and from O.6 to 1.6% (1995)

The use of flux-corer experiments in the determination of heavy metal re-distribution in and of potential leaching from the sediments

Metal dynamics between sediments, interstitial water and overlying water are particularly complex. The movement of metals, their availability, and possible toxicity are influenced by various chemical and physical reactions and factors such as oxygen/redox gradients, pH, grain size, etc. To study the impact of oxygen on the release from and the re-distribution of Cd, Pb, Zn and Cu in sediments, flux-corer experiments have been optimised and performed.The flux experiment was carried out using 3 identical sediment cores. The first (control) sediment core was completely characterised before, the two other cores after the experiment. Pore water extractions and sequential extractions were performed on 2 cm depth intervals throughout the 20 cm long sediment cores.In the flux experiment, the sediment cores were exposed to a small volume of overlying water, which was continuously renewed. The change of trace metal mobility was assessed by following concentration-changes in the outflow. It has been found by the use of the flux-corer experiment, that the Cd, Pb, Zn and Cu concentrations in the outflow are at least 3–6 times higher during oxic conditions. Flux-corer experiments can be useful tools to facilitate the study of the change of heavy metal mobility and distribution in the sediment induced by the change in surface water policy

A box-model of metal flows through the Scheldt estuary (1981-1983 and 1992-1995)

The behaviour of Cu, Zn, Cd, and Pb in the Scheldt estuary was investigated in the periods 1981 to 1993 and 1995. The Hg behaviour was studied between 1992 and 1994. A box model was used to establish the relationship between the trace metal inputs and the fate of these pollutants in the Scheldt estuary. Annual budgets were calculated for particulate and dissolved trace metals. For Hg, seasonal budgets of the various species (inorganic Hg, methylmercury, Hg°) could also be calculated. These budgets allow an evaluation of the consistency of each individual flux or process, such as the inputs of the various metals into the North Sea, the sedimentation flux of particulate metals in the area of high turbidity, the evasional fluxes and the formation rates of Hg°, etc. in relation to other ones

Total and toxic arsenic levels in North Sea fish

Levels of arsenic contamination in muscle and liver tissue of 25 sea fish and 4 shellfish species from the North Sea were determined. Analyses were done by both ICP-MS and HG-AFS to distinguish between nontoxic and toxic fractions of As. Highest total As concentrations were found in lemon sole, dogfish, ray, and witch. Average total As concentrations in these fish species were higher than 20 mg kg-1 WW. The same species as well as the other flatfishes contained the highest amounts of toxic As (> 0.1 mg kg-1 WW). Toxic fractions (AsTox/AsT%) above 2% were found in the following six species: seabass, ling, john dory, pouting, dab, and brill. No preferential concentration in the liver compared to the muscle was observed. In a worst-case scenario (when fish has been dried or smoked and the toxic As level is high; for example 0.5 mg kg-1 WW), the As content of North Sea marine food may reach harmful levels. A normalization reflecting the toxic potential of sea fish was made. Shark and ray and most flatfish species have positive (high) normalized AsTox values. By ANOVA testing we compared the individual AsT concentrations of samples of the same species (intraspecies variability). Significant differences for some fish species were observed; significantly higher AsT concentrations were found in dogfish from the French coast versus the western North Sea and in common sole from the Bay of the Seine, in the north of France, versus the western North Sea