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

Abstract

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.

Keywords: Bovidae; calf; energy; hand-rearing; lactation; protein.