Macronutrient composition of longitudinal milk samples from captive aardvarks (Orycteropus afer)

Abstract

Hand‐rearing and assisted‐rearing aardvarks in captivity has become commonplace and has led to success in breeding the species. However, the macronutrient content of aardvark milk past 1 month of age is unknown. A better understanding of aardvark milk composition would enhance captive management efforts. Here, we assayed milk samples from two captive individuals from 2 to 114 days postpartum (N = 21) for dry matter, fat, crude protein, total sugar, ash (total minerals), calcium (Ca), phosphorus (P), and gross energy. The body weight of one calf was measured from birth to weaning. Milk macronutrient composition was compared to that of other Afrotherian species and Xenarthra species with similar diets. Average protein, fat, and sugar concentrations of aardvark milk across lactation were 12.3%, 13.6%, and 2.5%, respectively. Ash averaged 1.9%, with Ca (0.50%) and P (0.35%) accounting for about 45% of total minerals. All measured nutrients increased over lactation except sugar, which decreased. Aardvark milk is high in energy (2.12 kcal/g) mostly derived from fat and protein and little energy from sugar. Calf growth was linear (r2 = 0.995) with a mean gain of 159 g/day, achieving almost 30% of adult weight at weaning. Within Afrotheria, aardvark milk is higher in fat and protein and lower in sugar than elephant milk and more closely resembles the milk of its fellow insectivore, the elephant shrew. Aardvark milk is also similar in composition to milk of insectivorous Xenarthra species (nine‐banded armadillo and giant anteater). Aardvark milk composition is consistent with the species’ high‐protein diet, fast growth, and nursing pattern.

Macronutrient composition of olive baboon (Papio anubis) milk: A comparison to rhesus macaque (Macaca mulatta) milk

“…This method of GE calculation may be a slight overestimate because it does not account for nonprotein nitrogen. However, this calculated GE value has been shown to closely correlate with experimentally measured gross energy using adiabatic bomb calorimetry for milk from species as diverse as aardvarks ( Orycteropus afer , Wenker et al, 2019), bongos ( Tragelaphus eurycerus , Petzinger et al, 2014), and rhesus macaques ( Macaca mulatta , Hinde et al, 2009).…”

Macronutrient composition of milk from two captive African elephant (Loxodonta africana) cows

“…The closest relatives to the African elephant are the Asian elephant, also part of the order Probosidea, followed by dugongs and manatees (Wenker et al, 2019). For both these species, high fat and protein milk is consistent with the insectivorous maternal diet.…”

“…Variations in diet, lactation strategy, and infant growth rates may be responsible for some of the variation in milk composition of Afrotherians, although more data are needed on the different species to support this claim. Milk from aardvarks and elephant shrews have a much higher proportion of protein (12.3% and 10.8% respectfully) and fat (13.6% and 19.7% respectfully) in their milk with considerably lower sugar content (2.5% and 1.4% respectfully) than is found in African and Asian elephant milk (Wenker et al, 2019). For both these species, high fat and protein milk is consistent with the insectivorous maternal diet.…”

“…Since elephants travel with the mother and do not restrict nursing to a few bouts per day, they do not need such an energy dense milk. The high fat and high protein content of aardvark milk contribute to the high growth rate that allow offspring to reach 30% of adult weight within the first 3 months of lactation (Wenker et al, 2019). The African elephant calves in this study only reached 5.3% and 6.4% of adult weight in the first 3 months and had not reached 25% of adult weight by 970 days.…”

Macronutrient composition of milk from captive southern pig‐tailed macaques (Macaca nemestrina)

“…Milk composition for an individual can show variation over time and this may be reflective of the changing energetic requirements of the nursing infant as it grows ( M. mulatta , Hinde et al, 2009; Elephas maximus , Abbondanza et al, 2013; Dasypus novemcinctus , Power et al, 2018; Orycteropus afer , Wenker et al, 2019). In this investigation, with only two time points, we cannot draw concrete conclusions regarding specific changes; however, the trends we observe highlight that milk composition is not constant.…”