Epidemiological studies of pig diseases: 1. Use of French protocols for risk factor assessment to predict the health status of Australian herds

Objective To determine in Australian pig herds the accuracy of French protocols for risk factor assessment.
Procedure Data on health indicators and risk factors were collected for three syndromes, 'pre-weaning diarrhoea', 'post-weaning diarrhoea' and 'respiratory problems', using the French protocols. The protocols were used on 118 occasions in 32 Western Australian pig herds during 3 years (1988 to 1991).
Results There was a wide variation in pre-weaning performance, for example growth rate was 107 to 273 g/day (< 200 g/day in 33% of herds). Respiratory lesions at weaning were associated with poor pre-weaning performance. Post-weaning (21 days after weaning) growth rate was 114 to 408 g/day (< 250 g/day in 54% of herds). In the grower herds, 91% of herds had pneumonia, and growth rate was 439 to 625 g/day (< 550 g/day in 54% of herds). Pleurisy as well as pneumonia was associated with reduced growth rate. The risk factor most closely associated with respiratory health status was air volume per pig.
Conclusion Risk factors were most accurate at predicting the health status in post-weaning problems. A weaning weight of at least 7.9 kg and weaning age of 30 days optimised weaner performance. Stocking densities and shed designs providing at least 3 m³ air volume and 0.6 m² floor space per pig throughout the growing phase should be considered for an improved respiratory health status. Australian pig sheds often do not provide a satisfactory environment for optimum health. The technique of risk factor assessment as an aid to the maintenance of health in pig herds is applicable in Australia, but further research is necessary to determine the most important Australian risk factors.     

Nutrients, moisture and productivity of established forests

The response of a forest to nutrient and moisture stresses is reflected in nutritional, physiological, and structural changes that include efficiency of nutrient use, translocation and cycling of nutrients, transpiration, retention of foliage, below-ground and above-ground allocation of carbon, as well as the structural development of the forest stand and its growth characteristics. This article reviews the relationship of forest ecosystems to nutrient and moisture stresses and addresses the means by which productivity can be enhanced by altering nutrient and moisture regimes.

Considerable research has focused on optimizing productivity by minimizing nutrient and moisture stresses. Research involved in nutrient additions has led to the use of commercial fertilizers to improve forest productivity. The results suggest that many forests are deficient in N and P and, to a lesser extent, S, K, Mg and trace elements. The duration of response for most nutrient additions is, however, relatively brief and the efficiency of the tree in using fertilizer is relatively poor. Long-term correction of nutrient deficiencies is seldom achieved with chemical fertilizers. However, N added through symbiotic fixation or, on a more limited scale, through addition of municipal and industrial waste by-products, can provide an excellent long-term growth response.

It is seldom feasible to change the moisture regime of a forest ecosystem through irrigation. However, field trials involving irrigation have demonstrated that moisture stress can limit productivity. There are various ways of minimizing moisture stress without irrigation, including mulching, removing ground-cover vegetation, and changing the spatial characteristics of the forest cover.

Research trials show that forest ecosystems will respond to moisture and nutrient additions; however, these responses and interactions between nutrients and moisture are typically poorly understood, and many questions remain unanswered: Does fertilization increase moisture-use efficiency of a forest or simply improve the nutrition of the site? Does improving the moisture regime of a site improve productivity primarily by decreasing moisture stress or by increasing nutrient availability and the rate of nutrient uptake? Is there a synergism in growth response with the addition of both nutrients and moisture? The linkages between nutrients and moisture appear inseparable and confound experimentation in this field. Answers to these questions and issues need to be found for the future development of plantation forestry.     

Why extensive research and development did not promote use of peach palm fruit in Latin America

Agroforestry Systems - Peach palm (Bactris gasipaes) was domesticated as a fruit crop by the first Amazonians in traditional Neotropical agroforestry systems, but research and development...     

Computer simulations of homeward-migrating Fraser River sockeye salmon: is compass orientation a sufficient direction-finding mechanism in the north-east Pacific Ocean?

Computer simulations were used to investigate whether compass orientation is a sufficient guidance mechanism for sockeye salmon migrating to the Fraser River from their ocean foraging grounds in the north-east Pacific Ocean. Daily surface ocean currents, simulated by the ocean surface current simulations (OSCURS) model, were used to test the influence of currents on the return oceanic migration of Fraser River sockeye salmon. High seas tagging and coastal recover data of Fraser River sockeye salmon were used for the migration simulations. Surface currents were shown to increase the speed of the homeward-migrating sockeye salmon, as well as to deflect the fish in a north-eastward direction. In spite of ocean currents, all Fraser River sockeye salmon were able to reach their destination with a fixed direction and bioenergetically efficient swimming speed when migration was delayed until the last month at sea. Compass orientation alone was shown to be a sufficient direction-finding mechanism for Fraser River sockeye salmon.     

Evidence-based veterinary dermatology: a systematic review of interventions for treatment of Pseudomonas otitis in dogs

The efficacy and safety of pharmacological interventions to treat canine Pseudomonas otitis externa and media were evaluated based on the systematic review of clinical trials published between 1967 and 2006. Clinical trials were included if Pseudomonas species were cultured from the ears of dogs with otitis externa or otitis media prior to treatment, and if the outcome of these interventions was reported at the end of the study. Studies were compared with regard to design characteristics (randomization generation and concealment, masking, intention-to-treat analyses), benefit (microbiological and/or clinical resolution of the Pseudomonas otitis), and adverse effects. Ten trials reporting data on 162 patients and 13 different pharmacological interventions were identified. Based on the accepted criteria for quality of evidence, there is insufficient evidence for or against recommending the use of any of these treatments for Pseudomonas otitis in dogs. This is largely because there is only one trial supporting the use of each treatment option and none were randomized controlled trials. Future studies need to be prospective, randomized, blinded and controlled; designed to evaluate pharmacological interventions for otitis regardless of the infective organism; have appropriate statistical advice on recruitment numbers, the power of the study and appropriate statistical analysis; include details of underlying conditions and concomitant treatments; and be designed such that inclusion criteria include microbial culture and antimicrobial sensitivity, and outcome assessments include clinical examination, cytology and microbial culture.     

Drivers,challenges and opportunities of forage technology adoption by smallholder cattle households in Cambodia

Forage technology has been successfully introduced into smallholder cattle systems in Cambodia as an alternative feed source to the traditional rice straw and native pastures, improving animal nutrition and reducing labour requirements of feeding cattle. Previous research has highlighted the positive impacts of forage technology including improved growth rates of cattle and household time savings. However, further research is required to understand the drivers, challenges and opportunities of forage technology for smallholder cattle households in Cambodia to facilitate widespread adoption and identify areas for further improvement. A survey of forage-growing households (n = 40) in July–September 2016 examined forage technology adoption experiences, including reasons for forage establishment, use of inputs and labour requirements of forage plot maintenance and use of forages (feeding, fattening, sale of grass or seedlings and silage). Time savings was reported as the main driver of forage adoption with household members spending approximately 1 h per day maintaining forages and feeding it to cattle. Water availability was reported as the main challenge to this activity. A small number of households also reported lack of labour, lack of fencing, competition from natural grasses, cost of irrigation and lack of experience as challenges to forage growing. Cattle fattening and sale of cut forage grass and seedlings was not found to be a widespread activity by interviewed households, with 25 and 10% of households reporting use of forages for these activities, respectively. Currently, opportunities exist for these households to better utilise forages through expansion of forage plots and cattle activities, although assistance is required to support these households in addressing current constraints, particularly availability of water, if the sustainability of this feed technology for smallholder cattle household is to be established in Cambodia.     

Association and General Notes

In a field disease outbreak, 60 female goats died over a 2–3 week period. Necropsies of seven of these does revealed that six had an acute exudative necrotising broncho-pneumonia, and moderate to high numbers of Pasteurella haemolytica were isolated from their lungs. Caprine herpesvirus, identified as Bovid herpesvirus type 6, was isolated from the lungs of two of these does, including one with pneumonia, and from nasal swabs of in-contact goats. Clinical disease was only observed in does, and deaths began 3 weeks after the introduction of a mob of goat hoggets from another farm.