Increased concern about environmental degradation and a move towards sustainable farming systems has lead to closer attention being paid to farm dairy effluents (FDE). Treatment of FDE in New Zealand is mainly through land application, or through oxidation ponds. Since the introduction of the Resource Management Act, 1991, regional councils require dairy farmers to be more accountable for the management of effluent from their dairy farms. Regulations have been imposed to limit the application of nitrogen (N) to land from FDE, and these limits range from 150 to 200 kg N ha -1 yr -1 . Farmers, consultants, and regional councils require information on the chemical composition, particularly N content, of effluents, so that land effluent application systems can be designed and managed within the guidelines or regulations imposed. Data gathered from previous investigations on effluents in New Zealand found an average solids content of 0.9% dry matter. Between 1977 and 1997 the mean N content of FDE doubled from approximately 200 to 400 mg N I -1 . The trend for higher N concentrations is likely to continue as dairy herd numbers increase. The most likely reason for the increase in N is that volume of washwater used per cow has proportionately decreased as herd size has increased, thus, FDE has become more concentrated with levels above 400 mg N I -1 increasingly common. Average values of phosphorus (P) and potassium (K) in FDE were 70 and 370 mg I -1 , respectively. Slurries obtained from anaerobic ponds, which require periodic desludging about every 5 years, had average nutrient concentrations of 1650, 290, and 510 mg 1 -1 for N, P, and K, respectively, representing an accumulation of minerals over the 5 years.
The accumulation of cadmium (Cd), a biotoxic heavy metal, in the food chain is undesirable. A national survey of soils and plants and random testing of kidneys from grazing animals slaughtered for export was conducted to assess Cd accumulation in New Zealand (NZ) pastoral agriculture. Average total Cd content of pastoral soils (0-7.5 cm) was 0.44 (Xg Cd/g compared to 0.20 |xg Cd/g for "native" (non-agricultural) soils. Total soil Cd was highly correlated to total soil P. An increase in total soil P is a reflection of fertiliser history thus phosphatic fertiliser use is implicated in Cd accumulation in pastoral soils. The elevated pastoral soil Cd levels were not clearly reflected in grass or legume species but were displayed in weed species viz, 0.28 ug Cd/g c.f. 0.14 µg Cd/g for pastoral and native sites respectively. Over the period 1988-91, 22-28% of sheep and 14-20% of cattle kidneys sampled exceeded the NZ maximum residue level of 1 µg Cd/g. Kidney Cd content was highly age-related. Cadmium was also present in feral deer and feral sheep kidneys showing that Cd occurs naturally in the environment.
Aims: To identify the prevalence and types of Campylobacter jejuni carried by dairy cattle and the extent of overlap of these types with those causing disease in humans.
Methods and Results: Faecal samples from 410 dairy cattle were collected from 36 farms in the Matamata‐Piako district in New Zealand. Campylobacter jejuni was isolated on all 36 farms, with a prevalence of 51% (95% CI 45–57) in dairy cattle and 65% (95% CI 58–72) in calves. Eighty‐nine of these isolates were typed using Penner serotyping and pulsed field gel electrophoresis and were compared with 58 human C. jejuni isolates from people resident within this study area.
Conclusions: Campylobacter jejuni were found in the faeces of over half of the dairy cows and calves examined. Twenty‐one per cent of the bovine isolates and 43% of the human isolates formed indistinguishable clusters of at least one bovine and one human isolate.
Significance and Impact of the Study: While a direct link between bovine isolates and human cases was not demonstrated, the finding of indistinguishable genotypes among C. jejuni isolates from bovine and human sources confirms that dairy cows and calves are a potential source of human campylobacteriosis. Barriers to separate bovine faecal material from the general public are therefore important public health measures.
soils (11.4 mg kg-1). The main difference in heavy metal concentrations between non-farm and pastoral pasture species was in the weed component. In general, the Cu, Zn, Pb, and As concentrations were essentially pedogenic in origin.
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