Cholesterol values in free-ranging gorillas (Gorilla gorilla gorilla and gorilla beringei) and bornean orangutans (Pongo pygmaeus)

Cholesterol concentrations in captive gorillas and orangutans vary widely within species and average approximately 244 mg/dl for gorillas and 169 mg/dl for orangutans as published previously. The International Species Inventory System reports higher concentrations of 275 and 199 mg/dl for gorillas and orangutans, respectively. It is unknown whether these values were typical, influenced by captive management, or both. To answer this question, banked serum samples from free-ranging mountain gorillas (Gorilla beringei), western lowland gorillas (Gorilla gorilla gorilla), and Bornean orangutans (Pongo pygmaeus) were analyzed for total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol concentrations. Mountain gorillas did not differ significantly from free-ranging western lowland gorillas in cholesterol, triglyceride, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol concentrations, indicating mountain gorilla values could be a model for western lowland gorillas. Captive gorilla total cholesterol and low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than in free-ranging groups. Triglyceride concentrations for captive gorillas were significantly higher (P < 0.05) than the male mountain and western lowland gorillas, but they were not significantly different from the female mountain gorillas. Captive orangutan total cholesterol concentrations were only higher (P < 0.05) than the free-ranging female orangutans, whereas captive orangutan low-density lipoprotein cholesterol concentrations were significantly higher (P < 0.05) than both free-ranging male and female orangutans. Calculated and measured low-density lipoprotein cholesterol concentrations were compared for all free-ranging animals and were significantly different (P < 0.05) for all groups, indicating Friedewald's equation for calculating low-density lipoprotein cholesterol is not appropriate for use with nonfasted apes. The higher total cholesterol and low-density lipoprotein cholesterol concentrations in captive apes may predispose them to cardiovascular disease and might be attributed to diets, limited energy expenditure, and genetics.