Concept: The Handler
Reasons for performing the study: The ability of horses to habituate to novel objects influences safety in the horse-human relationship. However, the effectiveness of different habituation techniques has not been investigated in detail. Objectives: 1) To investigate whether horses show increased stress responses when negatively reinforced to approach novel objects, compared with horses allowed to voluntarily explore the objects and 2) whether a negatively reinforced approach facilitates object habituation. Methods: Twenty-two 2-3-year-old Danish Warmblood geldings were included. Half of the horses (NR group) were negatively reinforced by a familiar human handler to approach a collection of novel objects in a test arena. The other half were individually released in the arena and were free to explore the objects (VOL group). On the next day, the horses were exposed to the objects again without a human handler, to investigate the rate of habituation. Behavioural and heart rate responses were recorded. Results: All VOL horses initially avoided the unknown objects, whereas the handler was able to get all NR horses to approach and stand next to the objects within the first 2 min session. The NR horses had a significantly longer duration of alertness and a higher max heart rate in the first session. On the next day, however, NR horses spent significantly less time investigating the objects and had a shorter latency to approach a feed container, placed next to the objects, indicating increased habituation. Conclusion: A negatively reinforced approach to novel objects increases stress responses during the initial exposure but facilitates habituation in young horses. Potential relevance: Although a negatively reinforced approach appears beneficial for habituation, the procedure should be carefully managed due to increased stress responses in the horse, which may constitute a safety risk. Further experiments should aim to investigate differences in stimulus intensity.
Technical developments have made it possible to analyze very low amounts of DNA. This has many advantages, but the drawback of this technological progress is that interpretation of the results becomes increasingly complex: the number of mixed DNA profiles increased relatively to single source DNA profiles and stochastic effects in the DNA profile, such as drop-in and drop-out, are more frequently observed. Moreover, the relevance of low template DNA material regarding the activities alleged is not as straightforward as it was a few years ago, when for example large quantities of blood were recovered. The possibility of secondary and tertiary transfer is now becoming an issue. The purpose of this research is twofold: first, to study the transfer of DNA from the handler and secondly, to observe if handlers would transfer DNA from persons closely connected to them. We chose to mimic cases where the offender would attack a person with a knife. As a first approach, we envisaged that the defense would not give an alternative explanation for the origin of the DNA. In our transfer experiments (4 donors, 16 experiments each, 64 traces), 3% of the traces were single DNA profiles. Most of the time, the DNA profile of the person handling the knife was present as the major profile: in 83% of the traces the major contributor profile corresponded to the stabber’s DNA profile (in single stains and mixtures). Mixture with no clear major/minor fraction (12%) were observed. 5% of the traces were considered of insufficient quality (more than 3 contributors, presence of a few minor peaks). In that case, we considered that the stabber’s DNA was absent. In our experiments, no traces allowed excluding the stabber, however it must be noted that precautions were taken to minimize background DNA as knives were cleaned before the experiments. DNA profiles of the stabber’s colleagues were not observed. We hope that this study will allow for a better understanding of the transfer mechanism and of how to assess and describe results given activity level propositions. In this preliminary research, we have focused on the transfer of DNA on the hand of the person. Besides, more research is needed to assign the probability of the results given an alternative activity proposed by the defense, for instance when the source of the DNA is not contested, but that the activities are.
Three experiments, each using 280 pigs, were conducted in a simulated compartment to test the effect of angle of entrance (AOE) to the ramp (90°, 60°, 30° or 0°), ramp slope (0°, 16°, 21° or 26°), and an initial 20 cm step associated with 16° or 21° ramp slopes on the ease of handling, heart rate (HR) and behavior of near market-weight pigs during unloading. Heart rate (pigs and handler), unloading time, handler’s interventions and pigs' reaction were monitored. The results of the first experiment show that using a 90° AOE had detrimental effects on ease of handling (P < 0.05), pig's HR (P < 0.05) and behavior (P < 0.05). The 0° and 30° AOE appeared to improve the ease of unloading, while the 60° AOE had an intermediate effect. The 30° AOE appeared to be preferable, because pigs moved at this angle balked less frequently (P < 0.01) and required less manipulation (P < 0.05) than pigs moved with a 0° AOE. The results of the second experiment show that the use of a flat ramp led to the easiest unloading as demonstrated by the lower number of balks (P < 0.001) when pigs were moved to the ramp and the less frequent use of paddle (P = 0.001) or voice (P < 0.001) on the ramp, compared to the other treatments. However, the flat ramp did not differ from the 21° ramp in many of the variables reflecting ease of handling, which may be explained by the difference in configuration between the ramps. The results also show that the use of the steepest ramp slope had the most detrimental effect on pig's balking and backing up behavior (P < 0.001) and handling (touches, slaps and pushes) (P < 0.05, for all) when moved to the ramp, and on unloading time (P < 0.01). No differences in pig HR (P < 0.05) and ease of handling on the ramp (P < 0.05) were found between a 26° and a 16° ramp slope, suggesting that the length of the ramp may be one of the factors which make unloading more difficult. The results of the last experiment show that a step associated with a ramp made unloading physically more demanding at both 16° and 21° for the handler (P < 0.001) and pigs on the ramp (P < 0.05) as demonstrated by their greater HR. The greater difficulty of handling (P < 0.01), pig's reluctance to move (P < 0.05) and the increase in HR (P < 0.05) in pigs moved toward the 16° ramp with a step suggests that pigs perceived this ramp as more psychologically challenging. Making a few changes in terms of the design of the ramp could improve the efficiency of handling and reduce stress in pigs.