Comparison of Eimeria species distribution and salinomycin resistance in commercial broiler operations utilizing different coccidiosis control strategies

The purpose of the present study was to evaluate the species composition and salinomycin sensitivity of Eimeria oocysts isolated from commercial broiler farms that differed by means of coccidiosis control (anticoccidial drugs [ACD] vs. live oocyst vaccines [VAC]). A comparison of Eimeria species composition and salinomycin sensitivity was also made before and after a producer switched from salinomycin to live oocyst vaccines. In general, no significant difference was observed in the concentration of Eimeria spp. oocysts in litter from VAC-utilizing farms compared to litter from ACD-utilizing farms. Application of PCR-based methods to detect coccidia found that Eimeria species distribution in litter from VAC operations more closely resembled the species composition in the live oocyst vaccines. Drug sensitivity testing found that Eimeria oocysts from VAC operations displayed greater salinomycin sensitivity as measured by weight gain and feed conversion efficiency compared to oocysts from ACD farms. These findings provide additional evidence for the usefulness of live oocyst vaccines to restore ionophore sensitivity in poultry operations that contain an ionophore-resistant population of Eimeria spp. oocysts.     

Linking temperate demersal fish species to habitat: scales,patterns and future directions

Adoption of the ecosystem approach to fisheries management relies on recognition of the link between fish and other components of the ecosystem, namely their physical and biological habitat. However, identifying the habitat requirements of marine fishes and hence determining their distribution in space and time is scientifically complex. We analysed the methodologies and findings of research on temperate, demersal fish habitat requirements to highlight the main developments in this field and to identify potential shortfalls. Many studies were undertaken over large spatial scales (≥100s km²) and these generally correlated abundances of fish to abiotic variables. Biological variables were accounted for less often. Small spatial scale (≤m²), experimental studies were comparatively sparse and commonly focused on biotic variables. Whilst the number of studies focusing on abiotic variables increased with increasing spatial scale, the proportion of studies finding significant relationships between habitat and fish distribution remained constant. This mismatch indicates there is no justification for the tendency to analyse abiotic habitat variables at large spatial scales. Innovative modelling techniques and habitat mapping technologies are developing rapidly, providing new insights at the larger spatial scales. However, there is a clear need for a reduction in study scale, or increase in resolution additional to the integration of biotic variables. We argue that development of sound predictive science in the field of demersal fish habitat determination is reliant on a change in focus along these lines. This is especially important if spatial management strategies, such as Marine Protected Areas (MPA) or No Take Zones (NTZ), are to be used in future ecosystem‐based approaches to fisheries management.     

Salinity Effects on Early Life Stages of Southern Flounder Paralichthys lethostigma

Abstract.— In South Carolina, studies have been conducted to develop rearing techniques for southern flounder Paralichthys lethostigma a candidate for aquaculture development and stock enhancement programs. To help define environmental tolerances, a variety of salinity studies were conducted with the early life stages of this species. Eggs were buoyant at 32 ppt and sank at 29 ppt with salinities of 30–31 ppt providing varying levels of suspension in the water column. Eggs incubated at 0 and 5 ppt all died, whereas 82.5% hatched at 10 ppt but larvae died shortly thereafter. At 63 h post-fertilization, there were no differences in hatch level for eggs incubated at salinities of 15 to 35 ppt (mean hatch level 98.5%). In a 72-h study, fish 3 wk post-metamorphosis (13.7 mm TL, 50-d-old) were acclimated to seven salinities ranging from 0–30 ppt. Fish held at 0 ppt salinity exhibited a statistically (P < 0.05) lower survival (20.0%) than those exposed to 5–30 ppt salinity concentrations. No differences were detected in survival (mean 99.1%) among fish held in the higher salinities. A second study examined the tolerance of older juveniles to lower salinities. Juvenile flounder (95.2 mm TL, 220-d-old) were acclimated to 0, 1,5 and 10 ppt salinities and reared for 2 wk. Results showed that fish could tolerate salinities of 0–10 ppt (100% survival). These data indicate that salinity tolerance of southern flounder increases with age. In addition to the short duration studies, a replicated 11-mo duration tank grow-out study was conducted at mean salinity 5.4 ppt and mean temperahue 22.6 C with an all male population. Flounder grew from a mean length of 100 mm to 213 mm TL and weight from 8.9 to 104.3 g. Growth of the cultured fish approximated that observed among male flounders in the wild.     

Theileria orientalis MPSP types in Australian cattle herds associated with outbreaks of clinical disease and their association with clinical pathology findings

Between September 2010 and November 2011, 350 EDTA blood samples were received from 73 Australian cattle herds, as cases suspected to be infected with Theileria orientalis. Beef cattle were predominantly affected, with Angus and Angus-crossbred cattle representing 48% of smear positive samples examined. DNA extracts were tested in conventional polymerase chain reaction (PCR) assays for genes encoding the p32, Ikeda, Chitose and Buffeli major piroplasm surface proteins (MPSP). PCR findings were compared with results of clinical pathology examinations of stained blood smears for parasitaemia and packed cell volume (PCV). PCR testing was much more sensitive than clinical pathology examinations in detecting T. orientalis infections, and concurrent testing of neat and diluted extracts gave significantly more PCR positive results than testing of neat extract alone. Significant associations and correlations were shown between PCR results of p32 and Ikeda assays with PCV levels indicative of anaemia, and with the level of parasitaemia estimated by smears. A high proportion of samples had concurrent Ikeda and Chitose infection, and significantly more clinical cases of theileriosis were associated with the Ikeda MPSP type as the sole infection, compared with sole infection with types Chitose or Buffeli. The findings indicate Ikeda type organisms were significantly associated with clinical parameters of theileriosis in cattle herds in eastern Australia, and that this type is most likely to be responsible for outbreaks of theileriosis experienced in affected Australian herds. In New South Wales, 11 of 14 regulatory districts yielded Ikeda positive samples, with five (Mid-Coast, Cumberland, Central North, Hume and Lachlan) containing 234/307 (76%) of the Ikeda positive samples.     

What are the prospects for black bream Acanthopagrus butcheri (Munro) aquaculture in salt‐affected inland Australia?

Black bream are a highly regarded sport and table fish, and there has been considerable interest in their aquaculture potential for the salt‐affected agricultural regions of inland southern Australia. In many ways they are an ideal candidate species for inland saline aquaculture because they appear to be very hardy, hatchery techniques are well established for them, and high survival rates have been maintained under a variety of culture conditions and feeding regimes. However, their slow growth rate needs to be increased by at least 33% for black bream to become an economically viable aquaculture species. Growth is amenable to genetic improvement, and sub‐adult growth rate shows moderate heritability and no adverse genetic correlations with other production traits. Nevertheless fillet yield is comparatively low, and in conjunction with unpredictable and early sexual development in culture, industry‐scale meat production remains problematic. These obstacles, however, do not preclude the use of black bream as a recreational fish species for inland saline waters, where their stocking may provide an additional source of rural income and relieve fishing pressure on depleted estuarine populations.     

Application of polymerase chain reaction based on ITS1 rDNA to speciate Eimeria

A method was developed to recover Eimeria spp. oocysts directly from poultry litter and determine which species of Eimeria were present using polymerase chain reaction (PCR) based on the ITS1 rDNA sequence. The species composition of Eimeria oocysts was also compared before and after propagation in susceptible chickens to determine if the relative proportion of each species changed after expansion. In samples from two broiler operations, ITS1-PCR was able to detect Eimeria spp. oocysts recovered from litter, with Eimeria acervulina, Eimeria maxima, and Eimeria praecox being the predominant species present therein. Although Eimeria tenella was found in one sample, the other species--Eimeria brunetti, Eimeria necatrix, and Eimeria mitis-were not detected. The species composition as determined by ITS1-PCR did not appear to appreciably alter after expansion in susceptible chickens. The described method represents a rapid means for determining the major Eimeria species in a poultry operation and may be helpful in choosing a particular live oocyst vaccine formulation to protect chickens against coccidiosis.     

The impact of biotechnology on agricultural worker safety and health

Biotechnology applications such as the use and production of genetically modified organisms (GMOs) have been widely promoted, adopted, and employed by agricultural producers throughout the world. Yet, little research exists that examines the implications of agricultural biotechnology on the health and safety of workers involved in agricultural production and processing. Regulatory frameworks do exist to examine key issues related to food safety and environmental protection in GMO applications. However, based on the lack of research and regulatory oversight, it would appear that the potential impact on the safety and health of workers is of limited interest. This article examines some of the known worker health and safety implications related to the use and production of GMOs using the host, agent, and environment framework. The characteristics of employers, workers, inputs, production practices, and socio-economic environments in which future agricultural workers perform various tasks is likely to change based on the research summarized here.     

Preface and acknowledgment

Preface and acknowledgment