Assessment of the risks of communicable disease transmission through the movement of poultry exhibited at agricultural shows in New South Wales

Objective To assess biosecurity practices in the fancy poultry show sector that would influence the establishment and spread of exotic diseases in poultry in New South Wales. Design A cross-sectional survey of 105 fancy poultry exhibitors at seven agricultural shows. Procedure Exhibitors were interviewed about biosecurity practices on their farms and their knowledge of exotic diseases. Poultry stewards at 18 shows were interviewed about biosecurity practices at their shows. Results Although many exhibitors travelled only short distances to attend shows, some exhibitors attended up to 30 shows per year and travelled interstate to exhibit poultry. A network diagram revealed extensive connections and interactions of poultry throughout the eastern half of NSW. Five of 18 shows included cash sales without any record of purchasers; 46% of exhibitors reintroduced exhibited birds back into their flocks without a quarantine period; and 16% failed to wash cages used to transport the birds. There was a general awareness that exhibition of birds posed a risk to flock health, but knowledge of avian influenza and practices that could be adopted to minimise the risk of disease introduction was limited. Conclusions The factors that could assist the establishment and spread of exotic diseases in poultry in NSW include the mixing of birds at shows, inadequate recording of exhibitor details at shows, inadequate biosecurity practices when reintroducing exhibited poultry back into flocks, cash sales associated with shows that did not include the collection of purchaser details, and inadequate identification of birds.     

Effects of increasing days of exposure to prepartum transition diets on reproduction and health in dairy cows

Objective To evaluate the effect of the number of days exposure to a prepartum transition diet on reproduction and health in dairy cows. Design A prospective cohort study. Procedures We enrolled 1008 dairy cows from three herds to examine the effects on reproduction and health of increased days exposure to prepartum transition diets that included ryegrass pasture, ryegrass silage, cereal hay, grain, by-products, oilseed meals, BioChlor®, rumen modifiers, minerals and vitamins. Diets provided 9.9 MJ metabolisable energy per kg dry matter (DM), a metabolisable protein balance of 286 g/day and a dietary cation anion difference of −150 meq/kg DM. Statistical models controlled for herd, calving day, age and gestation period. Results In two of the three herds increased days exposure to prepartum transition diets increased the hazards of submission for breeding, conception and clinical mastitis, and decreased the hazard of cow removal. The odds of pregnancy by 6 and 21 weeks after the mating start date tended to increase with increasing days of exposure to prepartum transition diets. Conclusions Increasing exposure to a prepartum transition diet improved the calving to conception interval, tended to improve the odds of pregnancy and reduced the risk of culling of cattle, but increased the hazard of clinical mastitis.     

Fertilizer‐use efficiency of different inorganic polyphosphate sources: effects on soil P availability and plant P acquisition during early growth of corn

Polyphosphate‐based fertilizers are worldwide in use, and their effect on crop yield is often reported to be similar to orthophosphate products, although some studies showed higher yields with polyphosphate applications. However, information on how these fertilizers may influence plant P acquisition is very limited. A pot experiment was carried out under controlled conditions with corn (Zea mays L.) growing on a sandy soil (pH 4.9) and a silty‐loam soil (pH 6.9) differing in P‐sorption properties. The objective was to evaluate phosphorus fertilizer–use efficiency (PFUE) of several polyphosphate (poly‐P) compounds (pyrophosphate [PP], tripolyphosphate [TP], and trimetaphosphate [TMP]) using orthophosphate (OP) as a reference. Focus was put on evaluating plant parameters involved in plant P acquisition, i.e., root length and P uptake per unit of root length. Furthermore, soil P availability was characterized by measuring ortho‐P and poly‐P concentrations in soil solution as well as in CAL (calcium‐acetate‐lactate) extracts. The P availability was differentially influenced by the different P sources and the different soils. In the silty‐loam soil, the application of poly‐P resulted in higher ortho‐P concentrations in soil solution. In the same soil, CAL‐extractable ortho‐P was similar for all P sources, whereas in the sandy soil, this parameter was higher after OP application. In the silty‐loam soil, poly‐P concentrations were very low in soil solution or in CAL extracts, whereas in the sandy soil, poly‐P concentrations were significantly higher. Phosphorus fertilizer–use efficiency was significantly higher for poly‐P treatments in the silty‐loam soil and were related to a higher root length since no differences in the P uptake per unit of root length among poly‐P and OP treatments were found. However, in the sandy soil, no differences in PFUE between OP and poly‐P treatments were observed. Therefore, PFUE of poly‐P compounds could be explained by better root growth, thereby improving plant P acquisition.     

Impedance Factor for Chloride Diffusion in Soil as Affected by Bulk Density and Water Content

The influence of soil bulk density and water content on the impedance factor (f) was studied by measuring bulk diffusion of chloride from one soil block to another differing in Cl^?-concentration. An increase in bulk density from 1.38 to 1.76 g cm^?3 at a constant gravimetric moisture content of 7% decreased f by a factor of 3, at 10% to 12% there was nearly no effect on f, while at higher soil moistures of 16% to 20%, f increased almost linearly with increasing bulk density. With increasing soil volumetric water content, (θ), f increased linearly at all soil bulk densities. At the same θ, the impedance factor decreased with increasing soil bulk density. The relationship between θ and f as established by Barraclough and Tinker (1981) agrees well with the results obtained here for bulk densities of 1.38 and 1.56 g cm^?3 and water contents higher than 18% (v/v). However, at lower values of θ, measured f values were higher than predicted by these authors. On the other hand, f values for a bulk density of 1.76 g cm^?1 at all water contents were clearly below the values of these authors.     

Reaktion der Zuckerrübe (Beta vulgaris var. altissima) auf die Kaliumdüngung – ein 20‐jähriger Feldversuch

Response of sugar beet ( Beta vulgaris var. altissima ) to potassium fertilization—a 20‐year field experiment A long‐term fertilizer experiment was performed to develop a K fertilization strategy to achieve highest extractable sugar yields (BZE). Sugar beet was grown in a crop rotation with wheat and barley on an alluvial soil (clayic silt) in Lower Saxony with annual recycling of straw and beet tops, respectively. Since 1983, the treatments were as follows: 1) K fertilization with 0, 29, 58, 87,174, and 524 kg K ha^–1 a^–1 corresponding to 0, 0.5, 1, 1.5, 3, and 9 times the average annual K removal by the marketable products of the crop rotation—since 1995, the two highest treatments (3 and 9 times the removal) received only 174 kg ha^–1 every third year; 2) K fertilization according to the average K removal, given each year (58 kg K ha^–1) or every third year (174 kg ha^–1) to sugar beet; 3) annual K fertilization of 87 kg K ha^–1 (1.5 times the removal) applied in autumn or spring, respectively; 4) annual K fertilization, applied as mineral fertilizer or as organic material (recycling of grain and straw or root and leaves); 5) application of 29 kg NaCl ha^–1 to sugar beet supplemental to a yearly application of 58 kg K ha^–1. Both root yield and soil concentration of lactate‐soluble K increased with K fertilization up to the highest K treatment. The extractable sugar content reached a maximum at a yearly application of 174 kg K ha^–1. Averaged over years, the extractable sugar yield (BZE) increased up to the highest K application. The time of K application (autumn or spring) and the source of K (mineral fertilizer or organic material) had no effect on BZE. An additional fertilization with NaCl increased BZE only slightly in single years. Low‐grade muriate of potash containing 33% K and 3% Na can thus be used. The economically optimal K‐fertilization rate was 174 kg K ha^–1 given once in the crop rotation to sugar beet. A soil K concentration of about 110 mg (kg soil)^–1 (lactate‐extractable K) is sufficient in this soil to achieve a high BZE.     

The survival and fecundity of buffalo flies after treatment of cattle with three anthelmintics

Two anthelmintics with known insecticidal action (ivermectin and closantel) and one with no recorded effect on insects (levamisole) were tested to evaluate their effects on buffalo fly (Haematobia irritans exigua). Blood from animals given closantel or levamisole had no significant effect on mortality of buffalo flies in an in-vitro assay. In contrast, blood from animals given ivermectin showed a dose-dependent effect on the mortality of buffalo flies. At 24 h after one injection of the recommended dose of ivermectin, 98% of the flies applied to cattle in an in-vivo assay are killed. Blood from cattle injected with ivermectin killed 95% of flies 8 d after injection and still killed 15% of flies at 18 days after injection. Surviving flies laid almost no eggs and this effect on flies was significant up to 33 d after injection. The results indicate that ivermectin may be useful to control buffalo fly populations in the field.