Metabolic and Microbial Characterizations for the Gastrointestinal Digesta of the Zoo Colobus guereza

Abyssinian black-and-white colobus (Colobus guereza) inhabits west, central, and east Africa and lives in social groups in the rain forests. Colobus guereza has a unique foregut digestive system similar to that of ruminants and absorbs organic acids, including Short-Chain Fatty Acids (SCFAs), as energy sources derived from microbial fermentation of plant materials in the gastrointestinal tract. In this study, the gastrointestinal metabolic and microbial features of a male Colobus guereza singly housed in a zoo were characterized, and each digesta from each segment of the digestive tract was collected and subjected to biochemical, microbiome, and metagenome analyses. In this case report, high levels of acetate and propionate were observed in the foregut, while a relatively high level of lactate was detected in the small intestine. Moreover, in the hindgut and the feces, acetate was dominant compared to the other SCFAs. SCFAs analysis indicated that Colobus guereza obtains energy via SCFAs, especially acetate, fermentation in the foregut and hindgut. A metagenome analysis revealed that each part of the digestive tract of Colobus guereza has a unique microbiota. Similar to ruminants, Prevotella and Selenomonas were the dominant genera in the foregut, which may indicate microbial fermentation of plant materials in the foregut of Colobus guereza.

Quantifying Mineral Intake and the Role of Minerals on Food Selection in Angola Black and White Colobus Monkeys (Colobus angolensis palliatus)

Minerals are vital for many metabolic processes, and mineral deficiencies can adversely impact health and fitness. Mineral concentrations of food items are commonly reported in primate nutritional ecology studies and have been identified as important factors in primate food selection; however, very few studies have quantified daily mineral intake of free-ranging primates. We examined the concentration of 9 minerals (Ca, P, Mg, K, Na, Fe, Zn, Cu, and Mn) in foods consumed by <i>Colobus angolensis palliatus</i> inhabiting the Diani Forest of Kenya, and test whether individuals preferentially selected leaves in accordance with their mineral concentrations. We also examined the effects of sex, group, and season on daily mineral intake, quantifying both percentage-based and mass-based intakes. We then compared daily mineral intake values to published recommendations. Behavioral data and plant samples were collected from July 2014 to December 2015. We found that individuals preferred leaves with greater P content and lower Ca content. Daily mineral intake differed significantly between sexes and among groups and seasons. These results are interpretable via differences in time spent feeding and total energy intake. Intakes fell below percentage-based recommendations for P, Na, Fe, Cu, and Mn but met or exceeded mass-based recommendations for all minerals except Na. This discrepancy is likely explained by the conservative nature of percentage-based mineral recommendations and the difficulty of comparing and scaling mass-based mineral recommendations among primate species. Studies that quantify daily mineral intake are needed to better understand the role of minerals on dietary selection, more accurately identify potential mineral deficiencies, and provide more informed recommendations for captive primates.

Feeding competition inferred from patch depletion in a supergroup of Rwenzori black-and-white colobus monkeys (Colobus angolensis ruwenzorii) in Rwanda

Competition for food is often a cost associated with living in a group, and can occur in an indirect (scramble) or direct (contest) form. We investigated feeding competition in a supergroup of Rwenzori black-and-white colobus monkeys (Colobus angolensis ruwenzorii) in Rwanda, with the aim of establishing whether freedom from scramble competition allows these monkeys to form supergroups. We used the patch depletion method, measuring intake rate coupled with movement rate, to assess if food patches become depleted over the occupancy period. Resource depletion was evident when the colobus fed on young leaves, but not when feeding on mature leaves. Scramble competition was inferred from a negative correlation between group size and change in intake rate over patch occupancy. Between-group contest competition was inferred from displacement from patches. Although feeding competition exists for select resources, limited competition for mature leaves may enable Rwenzori colobus to live in a supergroup of hundreds of individuals in this montane forest.