Does the milk of callitrichid monkeys differ from that of larger anthropoids?

Abstract

The generalization that anthropoid primates produce dilute milks that are low in protein and energy is based primarily on data from large monkeys of the families Cebidae and Cercopithecidae, as well as humans. The marmosets and tamarins (Callitrichidae) are not only much smaller in body size, but also typically raise multiple offspring during a relatively brief lactation. We hypothesized that selection for small body size and high reproductive rate might favor secretion of milk of higher energy and protein concentrations. To test this hypothesis, 46 milk samples collected from 10 common marmosets (Callithrix jacchus, ca. 350 g) were assayed for dry matter (DM), crude protein (CP), fat, and sugar; and gross energy (GE) was calculated from these constituents. We also assayed five samples collected from three golden lion tamarins (Leontopithecus rosalia, ca. 700 g) and six samples collected from a single pygmy marmoset (Cebuella pygmaea, ca. 150 g) over two lactation periods. All samples were collected between days 10 and 57 post partum, representing mid lactation for these species. The milks of these three species were similar, containing 14.0%, 16.1%, and 13.7% DM; 2.7%, 2.6%, and 2.9% CP; 3.6%, 5.2%, and 3.7% fat; 7.4%, 7.2%, and 7.8% sugar; and 0.76, 0.90, and 0.82 kcal/g for common marmosets, golden lion tamarins, and the pygmy marmoset, respectively. These species produced milks with energy values that were within the range reported for large anthropoids, albeit with slightly higher protein concentration. However, milk composition did vary substantially among individual common marmoset females, especially in the proportion of milk energy derived from fat. In contrast, CP as expressed as a percent of GE was remarkably constant among common marmoset females. Callitrichid milk appeared to be similar to that of larger anthropoid primates in GE, but was higher in CP and in the proportion of GE from CP. However, the small sample sizes for the golden lion tamarin and the pygmy marmoset, and the wide variation in milk composition found among common marmoset females cautions against definitively characterizing the milks of callitrichids from these data. Am.

The composition of milk from free‐living common marmosets (Callithrix jacchus) in Brazil

“…Contrary to what might be predicted based on their small body size, abbreviated lactation period and increased litter size, the average composition of callitrichid milk does not seem to differ substantially from that of other anthropoids [Power et al, 2002]. The composition of milk from captive common marmosets (Callithrix jacchus) is the best characterized, with 41 milk samples from ten individuals over 23 lactation periods.…”

“…Milk samples were collected between infant ages of 2-10 weeks, similar to the times of samples from Power et al [2002]. Captive marmoset milk samples do not systematically vary in composition over this time period [Power et al, 2002]. The ages of the infants were estimated two ways: observers followed the marmoset groups 2 days per week, and recorded the first sighting of infants.…”

“…However, there is significant variation in composition of milks not only among females, but also among litters for the same female. Milk fat is the most variable constituent, ranging from 0.7 to 12.9% among individual samples [Power et al, 2002]. Mean values of milk constituents, however, are within anthropoid norms.…”

“…Many, if not most species are capable of a fertile postpartum estrus, often resulting in multiple births per year. Lactation is relatively abbreviated, lasting only 2 or 3 months [Power et al, 2002]. A social structure that includes reproduction generally restricted to a single adult female per group, and a cooperative infant care system, which includes food provisioning of young by other group members, supports the rapid reduction in the infants' reliance on milk, enabling the abbreviated lactation period and shortened interbirth interval [Garber & Leigh, 1999].…”

“…To examine this issue, milk samples were obtained from feral, free-living common marmosets on a farm in the state of Rio de Janeiro, Brazil [Ruiz-Miranda et al, 2000]. These milk samples were assayed by methods identical to those employed to assay the milk samples from captive common marmosets reported in Power et al [2002].…”