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.     

How do resources influence control measures during a simulated outbreak of foot and mouth disease in Australia?

An outbreak of foot and mouth disease (FMD) could seriously impact Australia's livestock sector and economy. As an FMD-free country, an outbreak would trigger a major disease control and eradication program that would include the culling of infected and at risk animals (‘stamping out’), movement restrictions and zoo-sanitary measures. Additional control measures may also include pre-emptive culling or vaccination. However, it is unclear what disease strategy would be most effective under Australian conditions and different resource levels. Using a stochastic simulation model that describes FMD transmission between farms in a livestock dense region of Australia, our results suggest that using current estimates of human resource capacity for surveillance, infected premises operations and vaccination, outbreaks were effectively controlled under a stamping out strategy. However, under more constrained resource allocations, ring vaccination was more likely to achieve eradication faster than stamping out or pre-emptive culling strategies.     

分析中国栽培大豆遗传多样性所需SSR引物的数目

我国拥有极其丰富的大豆资源。传统的方法是根据农艺性状来分析其遗传变异，但农艺性状受自然环境和人为因素影响明显。随着大豆育成品种的增加，有限的表型变异已难以详细阐明我国2万余份大豆品种的遗传变异情况，需要从DNA分子水平深入研究我国大豆资源遗传变异分布规律。本研究以190份为大豆为初选核心种质的一个无偏样本。用60对SSR引物扩增，获得606个等位变异，平均每个位点有10个等位变异。位点多态信息量范围从0．55到0．99，平均为0．83。对190份大豆相似系数矩阵的标准误分析表明。SSR引物数增加到50左右时。再增加引物，标准误变化很小。共表型矩阵之间的相关性测验显示，当等位变异数达到570以上，相互之间相关性极显著。从实验材料中选取东北春大豆类型作为一个小样本进行共表型矩阵相关性分析也有类似结果。用SSR方法分析中国栽培大豆(G．max)遗传变异关系时，只有等位变异数达到一定的范围时，才能真实地反映出品种之间的遗传变异关系。当群体的遗传变异范围变得相对较小时。分析个体之间的遗传变异关系所需的等位变异数目也相应降低。结合SSR位点在大豆基因组中的分布和基因多样性水平。能够找到分析栽培大豆遗传多样性的核心SSR引物。只有获得等位变异数在570以上。才能客观地反映出中国栽培大豆遗传变异关系。     

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.     

The Use of River Flow Data to Predict Low Flows as an Aid to Trout Farm Management

Advance knowledge of flow rate variations in the water supply to a spring-fed trout farm is of great value to the farm manager since the weight of stock that can be sustained at any one time is dependent on the discharge rate of the spring. Annual variations of flow rate in groundwater dominated streams and rivers follow a fairly regular pattern with a recession occurring from the highest flows in the spring to the lowest flows in the late summer and autumn. This paper describes a simple technique for predicting discharge rates during periods of recession. Use of the technique which is illustrated by data from Belleau springs in Lincolnshire would enable fish farm managers to obtain a conservative estimate of the flows during summer and autumn and give adequate forewarning of impending low flows.