Physiological costs of infection: herpesvirus replication is linked to blood oxidative stress in equids.

Viruses may have a dramatic impact on the health of their animal hosts. The patho-physiological mechanisms underlying viral infections in animals are, however, not well understood. It is increasingly recognized that oxidative stress may be a major physiological cost of viral infections. Here we compare three blood-based markers of oxidative status in herpes positive and negative individuals of the domestic horse (Equus ferus caballus) and of both captive and free-ranging Mongolian khulan (Equus hemionus hemionus) and plains zebra (Equus quagga). Herpes positive free-ranging animals had significantly more protein oxidative damage and lower glutathione peroxidase (antioxidant enzyme) than negative ones, providing correlative support for a link between oxidative stress and herpesvirus infection in free-living equids. Conversely, we found weak evidence for oxidative stress in herpes positive captive animals. Hence our work indicates that environment (captive versus free living) might affect the physiological response of equids to herpesvirus infection. The Mongolian khulan and the plains zebra are currently classified as near threatened by the International Union for Conservation of Nature. Thus, understanding health impacts of pathogens on these species is critical to maintaining viable captive and wild populations.

Global assessment of the non-equilibrium concept in rangelands.

The non-equilibrium concept of rangeland dynamics predicts that the potential for grazing-induced degradation is low in rangelands with relatively variable precipitation. To date, evidence in support of the non-equilibrium concept has been inconsistent. Using a standardized protocol, including a newly developed global map of rainfall variability, we reviewed the incidence of degradation in relation to rainfall variability across 58 published studies. We distinguished between (1) zonal degradation (i.e., degradation independent of water and key resources), (2) degradation in the presence of key resources, and (3) degradation in the presence of water. For studies not affected by proximity to permanent water or key resources, we found strong support for the non-equilibrium concept for rangelands. Zonal degradation was absent at CV (coefficient of variation) values above 33%, which has been proposed as a critical threshold. Grazing degradation was almost entirely restricted to areas with relatively stable annual precipitation as expressed by a low CV, or to rangelands with key resources or water points nearby. To better understand rangeland dynamics, we recommend that future studies use globally comparable measures of degradation and rainfall variability. Our work underlines that rangelands with relatively stable rainfall patterns, and those with access to water or key resources, are potentially vulnerable to degradation. Grazing management in such areas should incorporate strategic rest periods. Such rest periods effectively mimic natural fluctuations in herbivore populations, which are a defining characteristic of non-degraded rangelands occurring under highly variable precipitation regimes.

Time budget-, behavioral synchrony- and body score development of a newly released Przewalski's horse group Equus ferus przewalskii, in the Great Gobi B Strictly Protected Area in SW Mongolia.

The Przewalski's horse (Equus ferus przewalskii) became extinct in the wild in the 1960s, but survived as a species due to captive breeding. There have been several initiatives to re-introduce the species in central Asia, but until now only two projects in Mongolia establish free-ranging populations. Data on basic ecology and behavior of the species prior to extinction is largely lacking and a good documentation of the re-introduction process is essential. Between 13 May and 2 September 2003 we documented the time budget-, group synchrony and body score development of a newly released Przewalski's horse group in the Gobi area of SW Mongolia.Contrary to our expectations, the newly released Przewalski's horses did not show the expected succession of an exploration-, acclimatization-, and established phase. Grazing activity was very high after the release, decreased to a minimum in July and increased again towards the end of the study in September. Resting activity followed the opposite trend, whereas moving activity was more or less constant over the entire observation period. Behavioral synchronization of the group was high throughout the study period and immigration or emigration of members did not result in a de-synchronization of the group. The body score index never dropped, but rather increased for all group members.Our data suggests that captive bred Przewalski's horses experience little behavioral and nutritional stress when being released into the desert steppe of the Gobi regions after one year in an adaptation enclosure.