Proximate composition of milk from free-ranging mountain gorillas (Gorilla beringei beringei)

Published data on milk composition for nonhuman primates, especially great apes, are lacking. Milk composition data are important for understanding the physiology and evolution of mammalian milk production, as well as the nutritional requirements of infants. For many primate species these data have added relevance because of the need to hand raise infants orphaned by poaching or separated from their mothers in captivity. The proximate composition (dry matter (DM), protein, fat, sugar) of free-ranging mountain gorilla (MG) (Gorilla beringei beringei) milk was characterized from samples (N = 10) collected opportunistically during field procedures. The mean values for mid-lactation (1-50 months) milk samples from healthy MGs (N = 7) were: 10.7% DM, 1.9% fat, 1.4% crude protein, 6.8% sugar, and 0.53 kcal/g. These results are lower in fat and total energy than most other Hominidae, including humans. One early-lactation sample was high in protein content while the composition of two samples from gorillas with poor health and suspected poor milk quality both deviated from the normal, mid-lactation pattern. This survey adds to the data available for primate milk composition and suggests that wild MG infants normally consume milk that is lower in fat and total energy than human milk.