Twelve years experience in Switzerland: Quo vadis BSE?

When the first BSE case in Switzerland became public in 1990, it precipitated a chain of events with many diverse consequences. During this time, we continued to gain knowledge, implement new measures, and make practical recommendations in order to attempt to control the disease. This was made possible by the establishment of a huge data base containing information on all cases of BSE that had been diagnosed in Switzerland, as well as by the use of information from experiences in other countries. Analysis of these data allowed the sequence of events to be described temporally and spatially and an epidemiological evaluation to be made. These data also allow predictions to be made regarding the future of BSE in Switzerland, although these predictions must be interpreted cautiously.     

Can Sheep Control Invasive Forbs Without Compromising Efforts to Restore Native Plants?

Domestic sheep (Ovis aries) are increasingly being used to control non-native invasive plants in areas where restoration is a management goal. However, the efficacy of sheep grazing depends on both its potential for controlling undesirable plants and its ability to promote natives. To date, few studies have investigated impacts of sheep grazing on native forb recovery in North American grasslands. We assessed the impact of sheep on forbs by measuring the number of stems grazed before and after sheep foraged in western Montana, United States. Sheep grazed a higher percentage of non-native than native forbs (70% vs. 23%, respectively), and number of stems grazed was six times higher for non-natives than natives (48 vs. 5, respectively). Sheep preferentially selected the non-native forbs sulphur cinquefoil and yellow salsify over leafy spurge (fi = 2.075; fi = 0.969; fi = 0.969, respectively), as well as the native forbs white prairie aster (fi = 1.090) and blanketflower (fi = 1.000). Selection of native forbs was positively correlated with their pregrazing abundance and increased over the grazing period. Our findings indicate that when using sheep to control invasive forbs, appropriate timing and monitoring of grazing are critical for reducing nontarget impacts to native vegetation.