Gregory Timmel’s research while affiliated with University of California, Davis and other places

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Publications (3)


An example of a grooming network subjected to a community detection analysis (Louvain Method—Greedy Modularity Maximization). The results are plotted as a directed network graph where color is community, shape is sex, and size of the node is degree. Similar networks are used to identify the level of social integration of individuals and the likelihood impact of their removal on the social stability of the group. Figure 1 was generously provided by Brenda McCowan.
Provisioning of long-lasting produce was found to reduce socially inflicted trauma in large groups of rhesus macaques (Photo credit—Kathy West).
Using long-lasting produce (LLP) results in lower costs (a) and time (b) associated with veterinary treatment for socially inflicted trauma during the breeding season. Copied with permission from McCowan et al., 2024, unpublished data.
An example of a social group of rhesus macaques at the CNPRC.
Behavioral management staff train the macaques, using positive reinforcement techniques for a variety of purposes, including shifting.
Shared Accountability Shaping the Destinies of Individual and Groups of Nonhuman Primates
  • Article
  • Full-text available

October 2024

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53 Reads

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Gregory Brion Timmel

Simple Summary At the California National Primate Research Center (CNPRC), rhesus macaques are kept in large, complex social groups outdoors because this environment helps them behave naturally and cope well. However, living in groups can lead to problems, such as fights that sometimes result in injuries. To handle these situations, a team of experts from different fields regularly meets to discuss and decide if any macaques need to be moved to protect them from repeated attacks. The team uses a careful process to identify which animals might be at risk and decide whether the individual should stay in the social group or be relocated, keeping in mind both the animal’s well-being and the stability of the whole group. This paper includes real-life examples to show how they make these tough decisions, aiming to keep all the animals physically and mentally healthy while maintaining harmony in the group. Abstract At the California National Primate Research Center (CNPRC), the preferred housing for rhesus macaques involves maintaining them in complex social groups outdoors, primarily for breeding purposes. This functionally appropriate environment promotes effective coping through the expression of species-typical behaviors and important aspects of species-typical social structure, thus enabling normal animal development, higher reproductive success, and the production of high-quality biological models. Despite the benefits, social housing introduces challenges like trauma from aggressive interactions. These challenges necessitate a delicate balance between tolerating some aggression and preventing repeated targeting of individuals. Therefore, the CNPRC has established a multidisciplinary working group of behavioral management experts, veterinarians, animal care, and researchers that meets regularly to review cases of animals that may need to be removed from their social group. We discuss the criteria and decision-making processes employed to manage and mitigate aggression. We describe the systematic approach to identifying at-risk individuals and the comprehensive evaluation process that guides whether to relocate an animal from their groups or not. Considerations include the welfare of the individual and the group’s social stability. This paper provides case studies demonstrating how the working group applies these criteria and processes in practical scenarios, highlighting the complexities and challenges of such decisions.

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Common Husbandry, Housing, and Animal Care Practices

February 2023

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100 Reads

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9 Citations

Animal care in facilities housing nonhuman primates has undergone a transformation in the past two decades, as the scientific community has learned more about the effects of husbandry practices on behavior and physiology of captive nonhuman primates. Today, husbandry consists of more than simply feeding animals and removing waste. Husbandry practices cover all aspects of animal care, from ensuring the animals’ nutritional needs to providing adequate shelter, monitoring the health of the animals, and refining procedures so that they reduce stress and distress. As such, husbandry is integral to providing optimal animal welfare. This chapter will summarize four main areas of husbandry (health monitoring, nutrition, shelter, and humane handling) and discuss how each can influence aspects of the welfare of captive nonhuman primates living in a research environment.


Interferon‐Gamma test for the detection of Mycobacterium tuberculosis complex infection in Macaca mulatta and other non‐human primates

May 2019

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65 Reads

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4 Citations

Journal of Medical Primatology

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Kamm Prongay

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Jeffrey A. Roberts

We have formatted an assay to detect Mycobacterium tuberculosis complex infections of non‐human primates. Commercially available reagents were used to elicit a specific immune response that was measured by interferon‐gamma release. Initial evaluation using blood samples from Rhesus macaques experimentally infected with M tuberculosis distinguished infected versus uninfected animals.

Citations (1)


... In NHPs, two commercial TB-IGRA kits, PrimaGAM and gamma-interferon test (GIFT) assay, used different mitogens to stimulate lymphocytes. In PrimaGAM, Con A was used as a positive control mitogen [36], while a combination of Con A+PWM mitogens was used as a positive control in the GIFT assay [37]. However, the concentration and minimal response to Con A were not determined. ...

Reference:

The new gamma interferon (IFN-γ) algorithm for tuberculosis diagnosis in cynomolgus macaques
Interferon‐Gamma test for the detection of Mycobacterium tuberculosis complex infection in Macaca mulatta and other non‐human primates
  • Citing Article
  • May 2019

Journal of Medical Primatology