Retrospective Evaluation of a Minor Dietary Change in Non-Diabetic Group-Housed Long-Tailed Macaques (Macaca fascicularis)

Evaluation of commercial diets on fecal consistency and defecation frequency in rhesus macaques (Macaca mulatta) with chronic intermittent idiopathic diarrhea

BACKGROUND

Recurrent diarrhea is common health and welfare problem in captive rhesus macaques (Macaca mulatta). Aside from infectious causes, dietary factors have been implicated in diarrhea. Therefore, the main objective of this study was to evaluate commercially available pelleted diets in rhesus macaques with chronic intermittent idiopathic diarrhea. The main differences between these diets were lactose and fiber content. A randomized cross-over diet study was conducted to investigate the influence of each diet on fecal consistency and defecation frequency as indicators of diarrhea. Nine animals with chronic intermittent diarrhea and four controls were included. Each diet was fed for approximately three months, with a similar wash-out period after each diet cycle. The fecal consistency was graded using the Waltham Faeces Scoring system, with a cutoff score of > 3.5 indicating diarrhea. Both groups and diets were compared by both mixed and fixed effect models.

RESULTS

Descriptive data showed that the mean fecal consistency score was highest in the diarrhea group in the standard diet at 3.71 ± 0.456 whereas the lowest mean fecal consistency scores were observed for lactose-free and high fiber diet in both diarrhea (3.25 ± 0.423) and control group (3.04 ± 0.346). A significant improvement of the fecal consistency score was detected in the diarrhea group when fed lactose-free diets (-0.41(-0.65 - -0.16, P < 0.01) and -0.47(-0.68 --0.25, P < 0.0002), respectively). Lactose-free and high fiber content showed the best outcome regarding improvement of the fecal consistency score -0.47(CL -0.68-- 0.25, P < 0.0002). Defecation frequency increased in both groups with 1.21(CL 0.65 - 1.78, P < 0.00001) per observation day when fed a lactose-free, high-fiber diet.

CONCLUSIONS

Lactose-free and high-fiber showed overall the best improvement of the fecal consistency in animals with diarrhea. Switching to commercially available lactose-free diets may decrease diarrhea incidence in rhesus macaques suffering from chronic intermittent idiopathic diarrhea. Nevertheless, additional nutritional research is warranted and establishing optimal nutritional requirements for captive macaques will add to our ability to understand and improve dietary interventions.

The Effects of the Fire Hose Square Knot Browser as a Foraging Enrichment Device on the Behavior of Captive Macaca fascicularis

Effective management of captive M. fascicularis (long-tailed macaques) is crucial for maintaining high-quality research models, necessitating strategies to promote their welfare. This study evaluated the impact of a foraging enrichment device, the "fire hose square knot browser", on the behavior of 32 long-tailed macaques at the Primate Research Center of IPB University in Bogor, Indonesia. We observed and analyzed daily behaviors across various food types over 288 h using scan and instantaneous sampling methods. Statistical analyses, including ANOVA and Kruskal-Wallis tests, revealed significant behavioral changes in the presence of the foraging enrichment device. The foraging enrichment device notably increased eating and affiliative behaviors, while reducing resting, agonistic, and stereotypic behaviors. No significant differences in eating, auto-grooming, resting, sexual, agonistic, or stereotypic behaviors were observed between the morning and afternoon. However, mobility and affiliation behaviors varied between these periods. The highest percentage of eating behavior occurred with the enrichment foraging device and a mixture of fruits. Furthermore, a three-way non-parametric analysis suggests a significant effect of food type and treatment on behaviors such as mobility and stereotyping. These findings underscore the positive impact of foraging enrichment devices on promoting active behavior and enhancing animal welfare in captive long-tailed macaques.

Reference Intervals and Percentiles for Hematologic and Serum Biochemical Values in Captive Bred Rhesus (Macaca mulatta) and Cynomolgus Macaques (Macaca fascicularis)

Several physiological characteristics and housing conditions are known to affect hematologic and serum biochemical values in macaques. However, the studies that have been conducted either report values calculated based on a small number of animals, were designed specifically to document the effect of a particular condition on the normal range of hematologic and serum biochemical values, or used parametric assumptions to calculate hematologic and serum biochemical reference intervals. We conducted a retrospective longitudinal cohort study to estimate reference intervals for hematologic and serum biochemical values in clinically healthy macaques based on observed percentiles without parametric assumptions. Data were obtained as part of the Biomedical Primate Research Centre (Rijswijk, The Netherlands) health monitoring program between 2018 and 2021. In total, 4009 blood samples from 1475 macaques were analyzed with a maximum of one repeat per year per animal. Data were established by species, gender, age, weight-for-height indices, pregnancy, sedation protocol, and housing conditions. Most of the parameters profoundly affected just some hematologic and serum biochemical values. A significant glucose difference was observed between the ketamine and ketamine-medetomidine sedation protocols. The results emphasize the importance of establishing uniform experimental groups with validated animal husbandry and housing conditions to improve the reproducibility of the experiments.

Guidelines on Models of Diabetic Heart Disease

Diabetes is a major risk factor for cardiovascular diseases, including diabetic cardiomyopathy, atherosclerosis, myocardial infarction, and heart failure. As cardiovascular disease represents the number one cause of death in people with diabetes, there has been a major emphasis on understanding the mechanisms by which diabetes promotes cardiovascular disease, and how antidiabetic therapies impact diabetic heart disease. With a wide array of models to study diabetes (both type 1 and type 2), the field has made major progress in answering these questions. However, each model has its own inherent limitations. Therefore, the purpose of this guidelines document is to provide the field with information on which aspects of cardiovascular disease in the human diabetic population are most accurately reproduced by the available models. This review aims to emphasize the advantages and disadvantages of each model, and to highlight the practical challenges and technical considerations involved. We will review the preclinical animal models of diabetes (based on their method of induction), appraise models of diabetes-related atherosclerosis and heart failure, and discuss in vitro models of diabetic heart disease. These guidelines will allow researchers to select the appropriate model of diabetic heart disease, depending on the specific research question being addressed.