Proximate composition of milk of the bongo ( Tragelaphus eurycerus ) in comparison to other African bovids and to hand‐rearing formulas

African bovids represent a highly diverse group with divergent neonatal care strategies. The extent to which their milks reflect this diversity is poorly understood. We analyzed milk of the bongo ( Tragelaphus eurycerus ) to compare its composition to milks of other African bovids and to evaluate bongo milk replacement formulas. Milk samples from three individuals (0 through 300 days postpartum, n  = 28) were assayed for dry matter (total solids), crude fat, crude protein, total sugar, ash, calcium, and phosphorus; gross energy was assayed on a subset of samples and compared to calculated values. Nutrient composition changed very little over the lactation period except for day 0 (colostrum) and the last sample (day 300). Bongo milk (days 6–286) contained (mean ± SEM): 28.1 ± 0.7% dry matter (71.9 ± 0.7% water), 12.3 ± 0.6% fat, 10.6 ± 0.3% crude protein, 3.6 ± 0.1% sugar, 1.05 ± 0.03% ash, 0.26 ± 0.01% calcium, 0.16 ± 0.01% phosphorus, and a GE of 1.88 ± 0.06 kcal/g. The protein content of bongo milk accounts for 33% of energy. High protein energy appears to be typical of Tragelaphines and of African bovids that utilize a “hider” system of postnatal care. The stability of milk composition until day 300 suggests complete weaning may not occur until 9 months rather than at 6 months of age, as commonly assumed. None of the milk replacement formulas previously used for bongos was well matched to bongo milk composition; therefore, a new milk replacement formula is proposed. Zoo Biol. 33:305–313, 2014. © 2014 Wiley Periodicals, Inc.