PubMed · 12968419
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Albert Marni Joensen. 2003-08-11. [When physicians cry].. https://pubmed.ncbi.nlm.nih.gov/12968419/
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Coral reefs are in decline worldwide from a combination of natural and human forces. The environmental compromises faced by coral reef habitats and their associated fishes are potentially stressful, and in this study we examined the potential for assessing stress levels in coral reef fish. We determined the feasibility of using fecal casts from parrotfishes for remote assessment of stress-related hormones (cortisol and corticosterone), and the response of these hormones to the stress of restraint and hypoxia. Measurement of these hormones in fecal extracts by high performance liquid chromatography (HPLC) was validated using mass spectrometry, chemical derivitization, and radioactive tracer methods. In aquarium-adapted parrotfish, baseline levels of cortisol and corticosterone averaged 3.4+/-1.1 and 14.8+/-2.8 ng/g feces, respectively, across 32 days. During 13 days of periodic stress these hormones, respectively, average 10.8-fold and 3.2-fold greater than baseline, with a return to near baseline during a 23-day follow-up. Testosterone was also measured as a reference hormone which is not part of the stress-response axis. Levels of this hormone were similar across the study. These fecal hormones were also measured in a field study of parrotfish in 10 fringing coral reef areas around the Caribbean Island of St. John, US Virgin Islands. Extracts of remotely collected fecal casts of three parrotfish species revealed no difference in respective average hormone levels among these species. Also, there was no difference in respective hormone levels between aquarium and field environments. However, levels of both cortisol and corticosterone, but not testosterone, were elevated in two of the 10 reef sites surveyed. This study demonstrates that parrotfish fecals can be collected in aquarium and field conditions and that steroid hormones in these fecals can be extracted and reliably measured. The study also demonstrates that cortisol and corticosterone in parrotfish fecals can be used as an indicator of the stress-response which is unlikely to be masked by intrinsic variability in the sample source, environment or methodology.
A retrospective analysis of seroconversion to Maedi-Visna virus (MVV) was carried out for 10 infected semi-intensively reared dairy-sheep flocks that were tested annually between 1994 and 1999. Four of the flocks raised replacement lambs artificially with bovine colostrum and milk replacement to avoid lactogenic MVV infection but did not prevent aerosol contact between replacements and other sheep in the flock. Flock culling percentages ranged between 14 and 25% and in eight flocks the number of sheep that seroconverted was similar to or lower than the number of sheep culled--suggesting that incidence could be reduced by culling seropositive sheep without increasing average culling percentages. Random-effects logistic regression indicated that seroconversion was associated positively with increasing contact with infected sheep and with lifetime MV-serological status of the dam (used as a proxy measure of genetic susceptibility), but not with mode of rearing pre-weaning (artificially or with a seropositive or seronegative dam). Our results indicate that when conditions allow efficient horizontal transmission, there is no evidence that lactogenic infection increases the risk of MV infection and that there is an important inheritable component of disease resistance or susceptibility.
OBJECTIVE: To determine whether vaccinated or conditioned feeder calves sold through special auctions in Ontario commanded a premium, compared with feeder calves sold at conventional auctions, and whether various physical characteristics of the calves were associated with the sale price. DESIGN: Cross-sectional study. ANIMALS: 14,037 calves sold through conventional and special auctions at the Keady Livestock Market during the fall of 1999 and 2000. PROCEDURE: Calves were observed as they were sold by lot in the auction ring. Lot characteristics and the price received for each lot were recorded. Multivariate analysis was used to estimate the effect of lot characteristics and sale type on price. RESULTS: Information was recorded for 2,601 calf lots. Multivariate analysis indicated that various lot characteristics were associated with sale price, with 68% of the variation explained by the model. Overall, lots sold at special auctions received a premium of 0.06 dollars/lb (Canadian dollars), compared with lots sold at conventional auctions. However, the premium varied with mean body weight of the lot and year. In addition, frame size, breed, body condition score, uniformity of the lot, weaning status, mean body weight, lot size, sex, year, and sale type were significantly related to sale price. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that producers selling calves at special auctions at this market received a premium, compared with producers selling calves at conventional auctions.