Comparison of a liquid and a powder insecticidal dressing to aid healing and prevent flystrike of mulesing wounds in lambs

A proprietary insecticidal mulesing powder containing diazinon and an experimental liquid dressing based on eucalyptus oil, naphthalene, cresylic acid and chlorfenvinphos in a carrier of liquid hydrocarbons and petroleum oil were compared for their ability to promote wound healing and reduce the incidence of fly strike in freshly mulesed lambs. Throughout the trial period of 4 weeks, fly trapping confirmed the presence of Lucilia cuprina in the paddock where the ewes and lambs were grazing At inspection one month after mulesing, no deaths had occurred since mulesing and no lambs showed evidence of cutaneous myiasis, although a number of their dams (with 8 months wool) were struck. At 4 weeks after mulesing, the wounds of the lambs treated with the experimental liquid dressing showed better healing than those treated with the powder dressing. It was concluded that both mulesing preparations were effective in inhibiting flystrike, but the liquid dressing promoted faster wound healing than did the powder.     

Thermohaline fine structure in an oceanographic front from seismic reflection profiling

We present acoustic images of oceanic thermohaline structure created from marine seismic reflection profiles across the major oceanographic front between the Labrador Current and the North Atlantic Current. The images show that distinct water masses can be mapped, and their internal structure imaged, using low-frequency acoustic reflections from sound speed contrasts at interfaces across which temperature changes. The warm/cold front is characterized by east-dipping reflections generated by thermohaline intrusions in the uppermost 1000 meters of the ocean. Our results imply that marine seismic reflection techniques can provide excellent spatial resolution of important oceanic phenomena, including thermohaline intrusions, internal waves, and eddies.     

‘Water war’ in the Mekong Basin?

The Mekong River system provides a crucial source of natural resources for riparian nations. However, the increasingly rapid pace of hydro‐development in the Mekong Basin is threatening the integrity of the river system, posing a real concern for Lower Basin states, which are particularly dependent on the basin. This scenario has led to warnings of armed conflict, or even ‘water war’, between riparian states. Certainly, the expanding scale of hydro‐development can be expected to continue increasing interstate tensions in the Mekong region; but are these tensions really likely to escalate to armed conflict? This paper explores this question by drawing on the water and conflict theory of Aaron Wolf. Ultimately, this paper concludes that interstate tensions over Mekong hydro‐development are unlikely to generate armed conflict. This is in part due to the strategic impracticality of such a conflict as well as the presence of a river basin management institution. Most compellingly, though, armed conflict is unlikely because the economic imperative shared by Mekong states is better served by cooperation – or at least non‐interference – than conflict, over regional hydro‐development. In closing, the paper urges that the study of water and conflict in the Mekong Basin be refocused at the intrastate level.     

Prevalence of Cysticercus bovis in Australian cattle

Objective The first national abattoir survey of Cysticercus bovis (‘beef measles’) in cattle was conducted in February 2008. Methods During the data collection period, 493,316 cattle were subjected to standard postmortem procedures, including incision of the masseter and heart muscles. On-site veterinarians were asked to record the location of any C. bovis cysts, as well as the National Livestock Identification System ear tag numbers of infected animals. Veterinarians were asked to submit samples for laboratory confirmation by histology and polymerase chain reaction testing. Results Of the 23 samples submitted, none was positive for C. bovis by either diagnostic method. Conclusions Occasional, isolated diagnoses of beef measles are still made in most states of Australia, but since the last regional surveys were conducted 30 years ago, when the estimated prevalence was 50 to 200 per 100,000 cattle slaughtered, the parasite has become extremely rare.     

An assessment of a composite sampling method for counting strongyle eggs in sheep faeces

The conventional method for estimating the average strongyle egg count for a group of sheep was compared with a single count from a group composite faecal sample. Sixty-one groups of field samples were used. Composite samples were prepared in the laboratory by pooling equal amounts of faeces from individual samples. Data were logtransformed for analysis to meet the assumption of normality. There were no significant differences in the variances and overall mean counts obtained by the 2 methods. The regression line of log (composite count) on log (group arithmetic mean) did not differ significantly from the line of identity. When untransformed egg count data were categorised as low, moderate and high, the 2 methods were in agreement for 53 of the 61 groups. The mixing and counting process used for both methods (modified McMaster technique) gave highly repeatable results (repeatability = 0.94). The composite method was a quicker and valid alternative to the conventional method for monitoring helminthosis in sheep flocks.     

Male‐biased sex ratio of nonanadromous Oncorhynchus mykiss in a partially migratory population in California

Abstract – Differential rates of anadromy between males and females are common in partially migratory salmonid populations, but this pattern is not fully clear for Oncorhynchus mykiss (rainbow trout/steelhead) from the limited but mixed data available. In particular, there are very few data on sex ratios of juvenile and nonanadromous (resident) fish to help assess sex composition of various life stages and life‐history types. We used a recently developed Y‐chromosome genetic marker to assess sex ratio of stream‐dwelling (i.e., juvenile and nonanadromous) O. mykiss in a small coastal basin in central California, USA. We analysed 384 samples collected from three contiguous study reaches over 3 years. Sex ratio was 1:1 among juvenile‐sized O. mykiss (<150 mm) but highly male‐skewed (83%) among nonanadromous‐sized individuals (≥150 mm), and this sex ratio × size pattern did not differ among years or study reaches. Our results suggest that the rate of anadromy differs between males and females in this basin. Our study also demonstrates the application of new genetic markers to determine sex composition of immature and nonanadromous salmonids, which will help assess sex‐specific life‐history behaviour in partially migratory populations of O. mykiss and other species.