Nutrition of the captive western lowland gorilla (Gorilla gorilla gorilla): A dietary survey

An overview of nutritional factors in the aetiopathogenesis of myocardial fibrosis in great apes

The main cause of mortality in great apes in zoological settings is cardiovascular disease (CVD), affecting all four taxa: chimpanzee (Pan troglodytes), bonobo (Pan paniscus), gorilla (Gorilla spp.) and orangutan (Pongo spp.). Myocardial fibrosis, the most typical histological characterisation of CVD in great apes, is non-specific, making it challenging to understand the aetiopathogenesis. A multifactorial origin of disease is assumed whereby many potential causative factors are directly or indirectly related to the diet, which in wild-living great apes mainly consists of high-fibre, low-carbohydrate and very low-sodium components. Diets of great apes housed in zoological settings are often different compared with the situation in the wild. Moreover, low circulating vitamin D levels have recently been recognised in great apes housed in more northern regions. Evaluation of current supplementation guidelines shows that, despite implementation of different dietary strategies, animals stay vitamin D insufficient. Therefore, recent hypotheses designate vitamin D deficiency as a potential underlying factor in the pathogenesis of myocardial fibrosis. The aim of this literature review is to: (i) examine important differences in nutritional factors between zoological and wild great ape populations; (ii) explain the potential detrimental effects of the highlighted dietary discrepancies on cardiovascular function in great apes; and (iii) elucidate specific nutrition-related pathophysiological mechanisms that may underlie the development of myocardial fibrosis. This information may contribute to understanding the aetiopathogenesis of myocardial fibrosis in great apes and pave the way for future clinical studies and a more preventive approach to great ape CVD management.

Survey of current group demographics and management practices of bachelor groups of western lowland gorillas (Gorilla gorilla gorilla) across North America

Recommendations for the successful management and maintenance of bachelor groups of western lowland gorillas (Gorilla gorilla gorilla) in zoological settings have been an increasingly prevalent focus within the zoological community. Over the past two decades, studies have examined the impact of various environmental factors on the stability of bachelor groups, proposed management strategies for bachelor groups, and compared behavioral trends between bachelor and mixed-sex groups. These studies have clearly demonstrated that bachelor groups are complex social units that require specialized management approaches. In this study, we aimed to assess the extent to which bachelor group management across North American zoos accredited by the Association of Zoos and Aquariums aligns with established recommendations. We distributed a comprehensive survey broadly encompassing habitat and housing, aggression and wounding, group demographics, feeding, and training to the 22 zoos housing bachelor groups as of 2019. We received completed surveys from 19 zoos, representing a total of 21 social units and 59 individual gorillas. We used descriptive statistics to represent the range of current management strategies across the surveyed population and ANOVAs to assess significant variation in key demographic variables. Our results demonstrate that a majority of zoos have adopted the best practices for the formation of social groups established by Stoinski et al. in 2004. However, there is much less standardization across zoos in protocols surrounding training and feeding. Additionally, important variables in the assessment of wounding, such as time of day and location, are often unknown or not observed by animal care professionals. We highlight these two areas as being of particular focus in developing and adhering to consistent protocols across institutions.

Prevalence of regurgitation and reingestion and occurrence of coprophagy in the North American AZA Gorilla (Gorilla gorilla gorilla) population

The aims of this study were to determine the current prevalence of regurgitation and reingestion (R/R) and gain an insight on the occurrence of coprophagy in the Association of Zoos & Aquariums (AZA) gorilla (Gorilla gorilla gorilla) population. To do this, an online survey was sent to all AZA accredited gorilla institutions in 2018. This survey collected information on the severity of R/R at the individual level and the occurrence of coprophagy at the zoo level. Previous research suggests more than half of zoo-housed gorillas in the North American population engaged in R/R and coprophagy to some extent. The current study had a 100% response and completion rate; data were collected on all 296 noninfant gorillas in the population. Responses indicated that 60% of the AZA gorilla population engages in R/R to some degree and 24% of the population are observed exhibiting coprophagy on a weekly basis. With this preliminary information on coprophagy, and the realization that the Zoo community has been unsuccessful at eliminating R/R over the past 30 years, the next steps should be aimed at empirically assessing the potential drivers of these behaviors. Continuing efforts to further understand and eliminate R/R and coprophagy in zoo-housed primates is important not only because these behaviors are unsightly to visitors, but more importantly, R/R and coprophagy may signal deficiencies in current practices surrounding animal care.

Effects of two dietary fiber levels on nutrient digestibility and intestinal fermentation products in captive brown howler monkeys (Alouatta guariba)

Herbivorous primates present a selective consumption profile and morphological adaptations to use the fibrous fraction of their diets. Brown howler monkeys (Alouatta guariba) are generalist herbivores; however, when kept under human care, they usually receive diets rich in fruits and with insufficient amounts of fiber. Thus, the objective of this study was to evaluate the effects of two levels of neutral detergent fiber (NDF) in howlers on apparent total tract digestibility coefficients (ATTDC), fecal consistency, and intestinal fermentation products. A group of 26 adult howler monkeys, 13 males and 13 females, were fed two diets formulated to have 33% or 40% NDF for 11 days, according to a randomized block design (N = 26). The block factor was the enclosures with one, two, or three individuals (each enclosure corresponded to an experimental unit), totaling in eight replicates per treatment. There were no differences in dry matter and nutrients intake between treatments (p > 0.05). The diet with 33% NDF resulted in higher (p < 0.05) ATTDC of crude protein and crude energy. However, lower fecal concentrations of short-chain fatty acids (SCFA) and dry matter were observed in the treatment with 33% NDF in contrast to the 40% NDF group (p < 0.05). We recommend the inclusion of higher fiber levels (40% NDF) in the diet of howler monkeys since there is evidence of greater production of SCFA and improvement in fecal consistency.

Assessment of Yangtze Finless Porpoises (Neophocaena asiaorientalis) through Biochemical and Hematological Parameters

Ghulam Nabi, Yujiang Hao, Xianyuan Zeng, and Ding Wang (2017) For the management of endangered species, a periodic health assessment is important, as diet in captivity is restricted due to cost and some nutrients are lost during the processing, storage and thawing of sh. The objective of this study was to compare and assess the nutritional, as well as the physiological health of both the captive and free-ranging Yangtze Finless Porpoises (YFPs) through biochemical markers, selected electrolytes, enzymes and hematological parameters. Our results showed statistically significantly (P < 0.05) higher levels of some biochemical markers (HDL-c/LDL-c, globulin, TP, Urea, Creatinine and BUN), enzymes (GGT), electrolytes (K⁺, Na⁺, PO₄ ^3- and Mg²⁺) and hematological (WBCs, lymphocytes, eosinophil) parameters in wild compared to the captive populations. However, the captive population also showed significantly (P < 0.05) higher levels of some biochemical markers (LDL-c, albumin and albumin/globulin), enzymes (AMS), electrolytes (Cl^-) and complete blood count (neutrophil, monocytes and basophil) parameters versus wild populations. Differences in the parameters of captive YFPs could be due to their limited diet of only three fish species as well as their environment (captivity). Whereas, wild YFPs, continuously feed on a large variety of live fish species and shrimp as they travel long distances. Our results suggest that mineral supplements be added to their diet. As well, improved physical fitness training and hygienic conditions are required for the effective management of captive finless porpoises.