ABSTRACT
Milk composition is a fundamental aspect of mammalian reproduction. Differences in milk composition between species may reflect phylogeny, dietary ecology, lactation strategy, and infant growth patterns, but may also vary within a species due to maternal body condition. This study presents the first published data on milk macronutrient composition of southern pig-tailed macaques (Macaca nemestrina) and compares the results with data on two other Cercopithecine species. Milk samples were obtained from five dams at 10- and 14-weeks postparturition. Macronutrient composition was determined at the Smithsonian's National Zoo and Conservation Biology Institute using proven methods developed over 30 years. On average (±SEM), the milk contained 83.9 ± 0.4% water, 6.7 ± 0.4% fat, 7.6 ± 0.1% sugar, 1.8 ± 0.1% protein, and 0.22 ± 0.01% mineral content. The Ca:P ratio was 1.8; concentrations of Ca and protein were correlated. Mean gross energy was 1.02 ± 0.03 kcal/g with most of the energy coming from fat (59.6 ± 1.5%), followed by sugar (29.9 ± 1.4%) and protein (10.5 ± 0.5%). The milks at 14 weeks of infant age were higher in energy than the milks at 10 weeks, with an increase in energy from fat (p = 0.005) and decrease in energy from sugar (p = 0.018). The energy from protein did not change (p = 0.272). Compared to captive rhesus macaque (Macaca mulatta) and olive baboon (Papio anubis) milk assayed by identical methods, captive pig-tailed macaque milk was higher in energy, but after accounting for the higher milk energy there was no difference in the proportions of milk energy from protein, fat, and sugar. The captive pig-tailed dams were significantly heavier than reported values for wild pig-tailed macaques, suggesting high body condition. High body condition in captive Cercopithecines appears to result in milk higher in energy, with more energy coming from fat and less from sugar. However, variation in the proportion of milk energy from protein in captive Cercopithecine milks appears relatively constrained.
Subject(s)
Milk , Nutrients , Animals , Female , Macaca mulatta , Macaca nemestrina , Milk/chemistry , SugarsABSTRACT
This study was designed to (1) characterize the macronutrient composition of olive baboon (Papio anubis) milk, (2) compare baboon milk composition to that of rhesus macaques (Macaca mulatta), and (3) evaluate the association between the proportion of milk energy derived from protein and relative growth rate within anthropoid primates. A single milk sample was collected from each of eight lactating olive baboons ranging between 47- and 129-days postparturition and six rhesus macaques from 15- to 92-days living at the same institution under identical management conditions. Macronutrient composition (water, fat, protein sugar, and ash) was determined using standard techniques developed at the Nutrition Laboratory at the Smithsonian National Zoological Park. Baboon milk on average contained 86.0% ± 0.6% water, 4.7% ± 0.5% fat, 1.6% ± 0.04% protein, 7.3% ± 0.07% sugar, and 0.165% ± 0.007% ash. Baboon milk gross energy (GE) averaged 0.81 ± 0.04 kcal/g with 51.9% ± 2.6% from fat, 11.8% ± 0.7% from protein, and 36.2% ± 2.0% from sugar. Baboon milk demonstrated strong similarity to milk composition of the closely phylogenetically related rhesus macaque (86.1% ± 0.3% water, 4.1% ± 0.4% fat, 1.69% ± 0.05% protein, 7.71% ± 0.08% sugar, 0.19% ± 0.01% ash, and 0.78 kcal/g). There was no statistical difference between baboon and macaque milk in the proportions of energy from fat, sugar, and protein. Baboon milk can be described as a high sugar, moderate fat, and low protein milk with moderate energy density, which is consistent with their lactation strategy characterized by frequent, on-demand nursing and relatively slow life history compared to nonprimate mammal taxa. The milk energy from protein of both baboon and macaque (12.8% ± 0.3%) milk was intermediate between the protein milk energy of platyrrhine (19.3%-23.2%) and hominoid (8.9%-12.6%) primates, consistent with their relative growth rates also being intermediate. Compared to these cercopithecid monkeys, platyrrhine primates have both higher relative growth rates and higher milk energy from protein, while apes tend to be lower in both.