Pre-parturition staphylococcal mastitis in primiparous replacement goats: persistence over lactation and sources of infection     

Iacome SC Jácome  Francisca GC Sousa  Candice MG De Leon  Denis A Spricigo  Mauro MS Saraiva  Patricia EN Givisiez  Wondwossen A Gebreyes  Rafael FC Vieira  Celso JB Oliveira 《Veterinary research》2014,45(1)

This investigation reported for the first time the occurrence of intramammary infections caused by Staphylococcus in primiparous replacement goats before parturition and the persistence of clinical Staphylococcus aureus infection during the lactation period. Subclinical infections, mainly caused by coagulase negative staphylococci (CoNS), did not persist during lactation. Genotyping analysis indicated that environment seems to play a moderate role as source of intramammary infections to goats before parturition, but causative agents of mastitis in lactating animals are not genotypically related to environmental staphylococci. The occurrence and persistence of intramammary infections in replacement goats demonstrate the need to consider those animals as potential sources of infections in dairy goat herds.  相似文献   

Tractor driving among kentucky farm youth: results from the farm family health and hazard surveillance project     

Browning SR  Westneat SC  Szeluga R 《Journal of agricultural safety and health》2001,7(3):155-167

This article documents the extent of children's involvement in tractor operations among a representative sample of Kentucky children living and working on family farms. Specifically, we describe children's exposures to tractor-related work activities, profile their use of the tractor (number of days worked), and assess compliance with generally recommended safety measures, such as using tractors equipped with ROPS (rollover protective structures), avoiding riding as passengers on tractors, and operating tractors on public roadways. Data for this study were collected in 1994 and 1995 as part of the NIOSH-sponsored Farm Family Health and Hazard Surveillance Project (FFHHSP). Despite recognition in the health and safety community of the hazards associated with operating tractors without ROPS on public roadways and with extra riders, these practices remain common among youth on Kentucky farms. Farms with annual incomes greater than $10,000, particularly with livestock commodities, appear to use youth for a greater number of days of tractor operation than other farms. Such farms may be an appropriate target for intervention.  相似文献   

Tracheal respiration in insects visualized with synchrotron x-ray imaging     

Westneat MW  Betz O  Blob RW  Fezzaa K  Cooper WJ  Lee WK 《Science (New York, N.Y.)》2003,299(5606):558-560

Insects are known to exchange respiratory gases in their system of tracheal tubes by using either diffusion or changes in internal pressure that are produced through body motion or hemolymph circulation. However, the inability to see inside living insects has limited our understanding of their respiration mechanisms. We used a synchrotron beam to obtain x-ray videos of living, breathing insects. Beetles, crickets, and ants exhibited rapid cycles of tracheal compression and expansion in the head and thorax. Body movements and hemolymph circulation cannot account for these cycles; therefore, our observations demonstrate a previously unknown mechanism of respiration in insects analogous to the inflation and deflation of vertebrate lungs.  相似文献   

Transmission of virulent footrot between sheep and goats     

SC GHIMIRE  JR EGERTON  OP DHUNGYEL 《Australian veterinary journal》1999,77(7):450-453

OBJECTIVE: To determine the infectivity of ovine and caprine strains of Dichelobacter nodosus for both sheep and goats. DESIGN: Pen experiments in which 20 sheep and 19 goats were challenged directly with the two strains, and transmission experiments on pasture, using donors infected by experimental challenge. RESULTS: Sheep and goat strains of D nodosus infected both animal species in experimental challenges. Animals so infected transmitted footrot to both sheep and goats on pasture plots. A significantly smaller proportion of goats than sheep was infected when challenged with either strain. The interval between exposure and development of footrot in goats was longer than in sheep when recipient animals were exposed to infected donors on pasture. The disease was less invasive in goats than in sheep. CONCLUSIONS: With the strains of D nodosus used there was no evidence of host specificity. Direct transmission of footrot can occur between sheep and goats in the same environment. There is a need to include goats in ovine footrot eradication programs and vice versa.  相似文献   

Phase velocities of rayleigh waves in the MELT experiment on the east pacific rise   总被引：2，自引：0，他引：2  

DW Forsyth  SC Webb  LM Dorman  Y Shen 《Science (New York, N.Y.)》1998,280(5367):1235-1238

The phase velocities of Rayleigh waves increase more rapidly with distance from the East Pacific Rise (EPR) axis than is predicted by models of conductive cooling of the lithosphere. Low velocities near the axis are probably caused by partial melt at depths of 20 to 70 kilometers in a zone several hundred kilometers wide. The lowest velocities are offset to the west of the EPR. Wave propagation is anisotropic; the fast direction is approximately perpendicular to the ridge, parallel to the spreading direction. Anisotropy increases from a minimum near the axis to 3 percent or more on the flanks.  相似文献