A framework for evaluation of on-farm mastitis diagnostics in Australia

Numerous culture-based diagnostics are available on the Australian and international markets for on-farm detection of bacterial pathogens in milk. Use of such diagnostics may provide an opportunity to improve the prudent use of antimicrobials in udder health management. Farms are low-resource settings in terms of diagnostic microbiology capacity. The World Health Organisation has identified criteria for the evaluation of diagnostic tests in low resource settings based on Accuracy, Sensitivity, Specificity, User-friendliness, being Rapid or Robust, Equipment-free and being Deliverable (ASSURED). Here, we review how those criteria can be interpreted in the context of microbiological diagnosis of mastitis pathogens, and how on-farm diagnostics that are currently available in Australia perform relative to ASSURED criteria. This evaluation identifies multiple trade-offs, both with regard to scientific criteria and with regards to convenience criteria. More importantly, the purpose of testing may differ between farms, and test performance should be evaluated relative to its intended use. The ability of on-farm mastitis diagnostics to inform mastitis treatment decision-making in a timely and cost-effective manner depends not just on test characteristics but also on farm-specific pathogen prevalence, and on the farm enterprise's priorities and the farm manager's potential courses of action. With most assay evaluations to date conducted in professional laboratories, there is a surprising dearth of information on how well any of the diagnostic tests perform on-farm and, indeed, of the on-farm decision-making processes that they aim to inform.     

Scrub-itch mite infestation in the endangered bridled nailtail wallaby

Skin lesions on the ears and inguinal and axillary regions of a number of adult animals within a captive population of the endangered bridled nailtail wallaby ( Onychogalea fraenata ) were associated with the trombiculid mite, Eutrombicula hirsti . The local inflammatory response of these Australian marsupials is described.     

Changes in fruit antioxidant activity among blueberry cultivars during cold-temperature storage

Antioxidant activity, total phenolic content, anthocyanin content, and six other fruit characters including titratable acid concentration, soluble solids, firmness, and percentage of bruised berries were determined for nine blueberry (Vaccinium L. sp.) cultivars at harvest and at various postharvest intervals after storage at 5 degrees C. Berries from MSU-58, Brigitta, and Legacy stored successfully for 7 weeks, Bluegold stored for 3-5 weeks, Bluecrop, Elliott, and Nelson stored for 3 weeks, and Jersey and Little Giant stored for fewer than 3 weeks. During the time they retained marketable quality, one cultivar (MSU-58) demonstrated a 29% increase in antioxidant activity. None of the cultivars showed a significant decrease from the harvest antioxidant activity value during storage. Antioxidant activity, total phenolic content, and anthocyanin content were strongly correlated with each other (r = 0.87-0.99, P < 0.01). All three parameters were moderately correlated with soluble solids (r = 0.47, P < or =0.05; r = 0.44, P < or = 0.05; and r = 0.64, P < or = 0.01, respectively), and antioxidant activity and total phenolic content were both moderately correlated with pH (r = 0.53 and 0.49, respectively; P < or = 0.05). However, antioxidant activity, total phenolic content, and anthocyanin content showed no correlation with firmness, percent severely bruised berries, or weight loss. Antioxidant activity and total phenolic content at harvest both correlated with titratable acidity at harvest (r = 0.68, P < or = 0.05 and r = 0.70, P < or = 0.05, respectively) on a cultivar mean basis. Berries from Elliott were also harvested from plants at two levels of bush ripeness (30-50% and 60-80% ripe berries on plants) and separated into three fruit maturity classes on the basis of percent blue color. The level of bush ripeness had no significant effect on antioxidant activity, total phenolic content, or anthocyanin content; however, fruit maturity had a significant effect on antioxidant activity, total phenolic content, and anthocyanin content, and bush ripeness x fruit maturity interactions were significant for these three traits. Berries with 50-75% blue coloration harvested from bushes with 60-80% mature fruit showed a significant increase in antioxidant activity, total phenolic content, and anthocyanin content during the first 3 weeks in storage. Our results demonstrate that increases in antioxidant activity, total phenolic content, and anthocyanin content may occur in the blueberry during cold storage and are cultivar-dependent. The increases that occur in immature fruit, such as in Elliott, may be advantageous for producers who wish to delay marketing of the fruit.     

Monitoring distances travelled by horses using GPS tracking collars

Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8–16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.     

Colonization of buried cotton stems by microarthropods

Initial colonization of cotton stems by microarthropods proceeded more rapidly while buried in soil under laboratory conditions (20–23°C) than while buried in the field during the winter months when soil temperatures ranged from 5–10°C in the study area in the San Joaquin Valley of California. While 15 species were found frequently in cotton stems held in the laboratory for 20 weeks, only seven species were found in field buried stems. Arthropods found under both conditions were a species of pyemotid mite; an astigmatid mite, Tyrophagus dimidiatus; two collembolans, Proisotoma minuta and Tullbergia sp.; and a sciarid fly larval stage, Bradysia impatiens. Even though the soils at teh field sites possessed a number of microarthropods in common, the stem colonization at each site was restricted to a single group which differed from each of the other sites. Microenvironments affect stem colonization patterns by microarthropods but microarthropods did not appear to have a significant influence on early cotton stem decomposition rates nor was there evidence that their activities reduced Verticillium microsclerotia populations.     

Deleterious Effects of Progestagen Treatment in VEGF Expression in Corpora Lutea of Pregnant Ewes

The aim of the current study was to determine the possible effects of progestagen oestrous synchronization on vascular endothelial growth factor (VEGF) expression during sheep luteogenesis and the peri‐implantation period and the relationship with luteal function. At days 9, 11, 13, 15, 17 and 21 of pregnancy, the ovaries from 30 progestagen treated and 30 ewes cycling after cloprostenol injection were evaluated by ultrasonography and, thereafter, collected and processed for immunohistochemical evaluation of VEGF; blood samples were drawn for evaluating plasma progesterone. The progestagen‐treated group showed smaller corpora lutea than cloprostenol‐treated and lower progesterone secretion. The expression of VEGF in the luteal cells increased with time in the cloprostenol group, but not in the progestagen‐treated group, which even showed a decrease between days 11 and 13. In progestagen‐treated sheep, VEGF expression in granulosa‐derived parenchymal lobule capillaries was correlated with the size of the luteal tissue, larger corpora lutea had higher expression, and tended to have a higher progesterone secretion. In conclusion, the current study indicates the existence of deleterious effects from exogenous progestagen treatments on progesterone secretion from induced corpora lutea, which correlate with alterations in the expression of VEGF in the luteal tissue and, this, presumably in the processes of neoangiogenesis and luteogenesis.     

Single Layer Centrifugation of Stallion Spermatozoa through Androcoll™‐E does not Adversely Affect their Capacitation‐Like Status,as Measured by CTC Staining

This study was designed to evaluate the effect of single layer centrifugation (SLC) and subsequent cold storage on stallion sperm capacitation‐like status and acrosome reaction. Three stallions were included in the study, with three ejaculates per stallion. The samples were examined 4, 24 and 72 h after collection, extension and SLC, with storage at 6°C. Sperm capacitation‐like status was investigated using the fluorescent dye chlortetracycline (CTC). There was no difference in capacitation‐like status between colloid‐selected and non‐selected spermatozoa. Sperm motility decreased significantly during cold storage, whereas the proportion of apparently capacitated spermatozoa increased. There was no change in the proportion of acrosome‐reacted spermatozoa. In conclusion, SLC through Androcoll?‐E does not adversely affect the capacitation‐like status of stallion spermatozoa, although it did increase with time during cold storage.     

Prediction of vertical soil organic carbon profiles using soil properties and environmental tracer data at an untilled site

Soil organic carbon (SOC) has considerable spatial and temporal variability both at the hillslope and catchment scale as well as down the soil profile. In recent years the distribution of SOC down the soil profile has become an area of interest in the understanding of the carbon sequestration potential of soils. Most studies however have concentrated on highly disturbed agricultural sites with little data available for untilled locations. In this study the vertical distribution of SOC is examined at a grassland site in the Young River area of Western Australia that has remained undisturbed by human activity for 50 years. Soil physical properties (texture, rock content) as well as the distribution of the environmental tracers ¹³⁷Cs and ²¹⁰Pb were assessed with the aim of better understanding the transport processes which produce the observed vertical distribution of SOC. While no consistent relationship was found between SOC and soil physical properties significant relationships were found between the distribution of SOC and the environmental tracers, ¹³⁷Cs and ²¹⁰Pb. Finite element simulations based on a diffusion/convection/decay model showed that the transport of ¹³⁷Cs and ²¹⁰Pb down the soil profile is likely to be driven by the same (primarily diffusive) processes. The same model used in conjunction with plant input and decay data generated from the RothC-26.3 soil carbon model revealed that transport of SOC down the soil profile, while also a diffusion process, was significantly slower indicating that different processes and/or pathways are involved in SOC transport at this site.     

Effects of ethanol extraction and duration of heat treatment of soybean flakes on the utilization of soybean protein by growing rats and pigs

Three experiments were conducted to determine the effects of ethanol extraction and duration of heat treatment of soybean flakes on the utilization of soybean protein by growing rats and pigs. In the first experiment, the treatments were no extraction or extraction with a 55% ethanol-water mixture (v/v), and heat treatments of 0, 5, 10, 20 and 40 min in an autoclave. Ethanol extraction improved rate (P less than .002) and efficiency of gain (P less than .001) of rats. As heat treatment was increased from 0 to 20 min, rate of gain increased, but it decreased again as heating time was increased from 20 to 40 min (P less than .03). In Exp. 2 and 3, 45 pigs were used in a growth assay and 54 were used in a N balance experiment to determine the effects of ethanol extraction on under-, intermediate- and over-processed soybean flakes (i.e., 5, 20 and 60 min of autoclaving). The heat treatments were applied either without, before or after extraction with ethanol. Responses in rate and efficiency of gain to ethanol extraction were greater for soybean flakes heated for either 5 or 60 min than for the soybean flakes heated for 20 min. When pooled across heat treatment, pigs fed the soybean flakes heated before or after extraction with ethanol gained faster (P less than .001), had greater gain:feed (P less than .001) and lower plasma urea concentrations (P less than .002) than pigs fed soybean flakes heated without extraction. Feeding soybean flakes heated and extracted with ethanol also resulted in greater apparent N retention (P less than .003), apparent N digestibility (P less than .001) and apparent biological value (P less than .03) than soybean flakes that were heated without extraction. Ethanol extraction improved the protein quality of soybean flakes, especially when the flakes were under- or overprocessed with heat.     

Subacute toxicity of dietary 3-acetyldeoxynivalenol in mice.

3-Acetyldeoxynivalenol was incorporated into a semisynthetic diet at levels of 2.5, 5, 10 or 20 ppm and fed to mice for up to 48 days. Body weights and feed consumption were determined, and blood samples for hematological evaluation were taken. Selected tissues were examined microscopically and the humoral immune response was assessed using the Jerne plaque assay. 3-Acetyldeoxynivalenol caused a dose-related depressed feed consumption within the first seven days and reduced body weight until day 14 when fed at levels up to 10 ppm. When fed at a level of 20 ppm, an initial depression in body weight gain and a general malaise were followed by a return to normal. At necropsy, no macroscopic or microscopic lesions could be found. The immune response was not significantly affected after seven or 14 days, but at 21 days, a dose-dependent enhanced response was observed. The findings indicate that, after an initial period of reduced feed intake, animals are apparently able to overcome the toxic effects of 3-acetyldeoxynivalenol.