Socialization strategies and disease transmission in captive colonies of nonhuman primates

Feasibility of successfully breeding rhesus macaques (Macaca mulatta) to obtain healthy infants year-round

Rhesus monkeys are typically seasonal breeders but can be induced to extend the timing of their mating and births under captive conditions. The following analyses evaluated the potential impact of extending their pregnancies and deliveries year-round. Birth records from a large breeding colony housed in an indoor facility with a constant 14-hr light/10-hr dark cycle were analyzed across 25 years to examine seasonal trends in monkeys that mated in one of two ways: spontaneous in social groups or with a scheduled, timed-mating protocol. The dates of delivery and birth weights for 2,084 infants were used in these analyses. Younger nulliparous females mating in social groups evinced a clear seasonal peak when birthing their first infant. However, older females, both primiparous and multiparous, could be bred continuously, which enable the birth of infants in every month of the year. Based on the live birth rate, infant birth weights, high survival rates, and the normal sex ratio of infants birthed year-round, there were no adverse effects of breeding rhesus monkeys in this way. The continuous availability of infant births can be very advantageous for many types of research programs.

Effect of living conditions on biochemical and hematological parameters of the cynomolgus monkey

The cynomolgus monkey (Macaca fascicularis) has been increasingly used in biomedical research. Although living conditions affect behavioral and physiological characteristics in macaques, little data is available on how living conditions influence blood-based parameters in the cynomolgus monkey. We hypothesize that there are significant differences in serum biochemical and hematological parameters in single-caged versus socially housed cynomolgus monkeys, and that age and sex influence the effect of living conditions on these parameters. Sixty single-caged and 60 socially housed cynomolgus monkeys were segregated by age group (juvenile, adult) and sex. The effects of living condition, age, sex, and the interactions between these factors on commonly reported serum biochemical and hematological parameters were analyzed by a three-way analysis of variance (ANOVA). Then, the differences between single-caged and socially housed subjects were tested in each parameter by Student's t-test. Creatinine, glucose, triglyceride, alanine aminotransferase, red blood cell volume distribution width (SD, CV), median fluorescence reticulocyte percentage, white blood cell and basophil counts, and monocyte (count, %) were lower in single-caged subjects. Blood urea nitrogen and globulin were lower in single-caged juveniles and adults, respectively. Red blood cell count, hemoglobin, hematocrit, and neutrophil (count, %) were higher, and reticulocyte and lymphocyte (counts, %) were lower, in single-caged juveniles. Mean corpuscular hemoglobin concentration was higher in single-caged subjects (but more pronounced in adults). Total protein was higher in single-caged juvenile males and lower in single-caged adult females. Alkaline phosphatase was lower in single-caged juvenile females. Mean corpuscular hemoglobin was higher, and high fluorescence reticulocyte percentage was lower, in single-caged adult males. In conclusion, living conditions significantly affect several serum biochemical and hematological parameters in the cynomolgus monkey, and these effects vary by age and sex. As this macaque is commonly housed under different living conditions, these findings should aid researchers in avoiding inaccurate conclusions concerning this species.

Social processes and disease in nonhuman primates: introduction to the special section

Most nonhuman primate species are remarkably social, but their social nature presents many challenges, including increased opportunities for pathogen transmission and development of disease (both physical and psychological). An interdisciplinary symposium was convened at the 2010 annual meeting of the American Society of Primatologists on the topic of social processes and disease in nonhuman primates, and four articles from that session, as well as a fifth that was separately solicited, appear in this special section. The articles reflect a variety of disciplines and perspectives that highlight the many ways that social processes can impact disease processes (and vice versa) in this highly social taxon. This is an increasingly active area of research interest as a consequence of technological developments and the availability of long-term field data. The continuing loss of primate habitat in the wild, climate change, and the need to manage high densities of primates in captivity, however, all add urgency to our need to better understand the bidirectional relationship between social factors and disease processes.