Pup mortality in laboratory mice – infanticide or not?

Background

Despite being the most commonly used mammal in biomedical research, problems with perinatal mortality in mice have received little attention and the causes of pup death are still poorly known. Females are often housed alone with their litters and since the lost pups are generally eaten, it is commonly assumed that the mother has killed them. However, more detailed observations than have been reported previously in the literature are required to establish if the cause of death is infanticide. Litter loss can only be prevented efficiently after underlying causes have been carefully investigated and interpreted. The aim of this study was to investigate if females actively kill their pups by observing the behaviour of females and pups in litters that later were lost. We used video recordings of females that lost their entire litter to observe females in detail from parturition until the pups died. In total, 10 C57BL/6 females (wildtype and the knockouts Hfe^−/− and β2m^−/−) were studied, housed in Makrolon II cages with or without access to a small amount of nesting material.

Results

Three of the females had pups that were never seen moving, and another three females had one or two pups that never moved, indicating that some pups were most likely still-born. In five females with live-born pups, detailed observations from the time when a pup was last seen moving until it died were possible to carry out. We observed females eating dead offspring and interacting with both moving and dead pups. However, we never observed a pup stop moving when manipulated by the female, nor were any wounds seen in the pups. Hence, we found no evidence of infanticide when studying females that had lost their entire litter.

Conclusion

These results suggest that other causes than infanticide plays a major role in mouse pup death, and stress the need for more systematic and careful investigations of the causality of litter loss.     

Mycobacterium avium infections in poultry--a risk for human health or not?

Avian tuberculosis is an animal disease notifiable for statistical purposes in Germany. Cases notified (between 130 and 230 annually) were primarily related to private flocks of pedigree poultry and layers consisting of less than 20 animals and individual animals in game enclosures and zoological gardens. Mycobacterium (M.) avium infection does not play any role in modern intensive poultry husbandry. Human M. avium infections have considerably gained in importance in the last two decades, mainly in HIV-infected patients. Due to the ubiquitous character of MAIC (Mycobacterium avium intracellulare-Complex), it is difficult to establish confirmed epidemiological associations with infections in humans. Surface and drinking water, soil and also foods as well as direct contact with infected birds (pet birds) have been discussed as possible sources of infection. Recently, strains of the serovars 1, 2 and 3 which have often been isolated from birds (bird-type strains) could be defined as a taxon on its own right among MAIC by using molecular-biological methods for MAIC typing (RFLP--restriction fragment length polymorphism and PFGE-pulsed field gel elektrophoresis). In exceptional cases only, strains of this character have been isolated from humans. Consequently, poultry-to-man transmission of M. avium appears to be a very improbable event. In contrast, extensive conformity has been found to exist between M. avium isolates of human origin and isolates from pigs. This fact has rightly given rise to assumptions of either the presence of epidemiological links between pigs and humans or of infection from common sources. In a summarizing view, it can be stated that M. avium infection of farm poultry is hardly of any importance for poultry production as well as for human disease. The importance of MAIC for infections in other farm animals (cattle and swine) is outlined and discussed.     

Heck cattle in the Oostvaardersplassen: risk for infectious diseases or not?

This article discusses risk analysis of infectious diseases in a cattle population. Heck cattle living in nature reserve 'De Oostvaardersplassen' were studied as an example of the risk analysis approach. Twenty-five adult cattle were tested for every infectious disease agent that the risk analysis indicated might be prevalent. All sampled cattle tested positive for Bovine Herpesvirus 1, whereas the prevalence of antibodies against other infectious disease agents was below the level that was assumed to be the threshold for spread of the disease to cattle in the surrounding areas. Risk management of infectious diseases was expressed in a so-called 'low-risk profile'. The risk of introduction or spread of infectious diseases was estimated to be very low as long as the population was kept strictly enclosed.     

To jump or not to jump? Strategies employed by leisure and sport horses

Show jumping is one of the most popular equestrian disciplines although strategic jumping per se is seldom used by free-living horses when negotiating obstacles that they might otherwise avoid. To establish if horses are naturally motivated to jump, we examined horses in a free-choice situation when negotiating various obstacles under test conditions. Eighteen leisure horses (LHs) and 16 sport horses (SHs) participated in a number of 2-choice tests. First, horses were presented with 2 optional routes during a “free-choice test” to reach a food stimulus. The choices were a shorter route (over an obstacle) or a longer route (around the obstacle). During 8 consecutive trials, the horses encountered an increase in obstacle height on every second trial as follows: 0, 20, 35, and 50 cm. In the “ridden test” after an initial conditioning period, the horses were tested with a Y-maze formation during 3 consecutive trials, where one element of the maze contained an obstacle arm (OA). The horses walked or trotted over the obstacle most frequently (59.9%) and jumped the obstacle in only 10.7% of the cases. For both the LH and SH groups, the horses' motivation to traverse the obstacle decreased as the obstacle height increased and only 44.1% of horses actually negotiated the 50-cm obstacle as compared with the 20-cm obstacle (85.3%). The LH group preferred to go around the obstacle significantly more often than the SH group (24 trials, 16.7% vs. 9 trials, 7.0%, for SH and LH, respectively; χ² = 6.81, N = 33, P = 0.0090). The LH group used a jumping strategy to clear the obstacle far less frequently (6 trials, 4.2%) than the SH group (23 trials, 18.0%; χ² = 9.96, N = 29, P = 0.0023). In the Y-maze trials, the LH group exhibited preference (40 per 54 trials, 74.1%; χ² = 12.5, P < 0.0001), and the SH group failed to exhibit any preference (20 per 48 trials; χ² = 1.33, P = 0.3123). There was no evidence of any correlation between the motivation to clear the obstacle and total number of OA choices in either the LH group (r_s = 0.13, P = 0.9594) or the SH group (r_s = ?0.25, P = 0.3492). The findings from the present study indicate that SHs are motivated and willing to jump obstacles more often than are LHs under similar conditions. However, the apparent reluctance of the horses overall to continue jumping as the obstacle height increases suggests that, in general, many horses could easily encounter excessive demands (overfacing) in sport. This issue should be carefully monitored in terms of equine training, competition, and welfare.     

To Insure or not to Insure? Factors Affecting Acquisition of Prescribed Burning Insurance Coverage

Prescribed burning is a widely used tool in forest and grassland management. However, because fire that escapes from a prescribed burn accidentally may cause property damage, injuries, and even human casualties, purchasing insurance to cover such damages may be beneficial for prescribed burn practitioners. Given that insurance coverage for prescribed fire is recently emerging, factors that determine burners’ decisions to purchase such insurance are largely unknown. On the basis of data from a survey of prescribed burn practitioners in 14 southern and midwestern states, we modeled prescribed burners’ likelihood of purchasing insurance with respect to demographic characteristics, land management objectives, and importance placed on regulatory compliance and land use practices. Results suggest that prescribed burn practitioners are more likely to obtain such insurance if they are landowners themselves or have a written prescribed burn plan. Age of respondents and the level of importance they place on compliance with environmental laws also had a significant positive effect on the likelihood of obtaining insurance coverage. Respondents were less likely to purchase insurance if their land management objective was to control invasive plants or they considered the availability of lower-cost alternatives for woody plant removal an important factor in deciding whether or not to conduct prescribed burns. These findings shed light on underlying factors influencing insurance coverage for prescribed burning and are potentially beneficial for promoting the acquisition of insurance among burn practitioners.     

Mycobacterium bovis at the animal–human interface: A problem,or not?

Mycobacterium bovis is a pathogen of significant importance in livestock and a wide range of wild animal species worldwide. It is also known to cause tuberculosis disease in humans, a fact which has raised renewed concerns regarding the zoonotic risk for humans, especially those living at the animal-human interface. This review consolidates recent reports in the literature mainly on animal and zoonotic tuberculosis with an emphasis on evolution, epidemiology, treatment and diagnosis. The information presented reveals the fundamental differences in the complexity and level at which the disease affects the economy, ecosystem and human population of regions where animal tuberculosis control is achieved and regions where little or no control is implemented. In conclusion the review suggests that bovine tuberculosis has essentially been reduced to a disease of economic importance in the developed world, while low-income countries are facing a multifaceted impact which potentially affects the health of livestock, humans and ecosystems and which is likely to increase in the presence of debilitating diseases such as HIV/AIDS and other factors which negatively affect human livelihoods.