The dynamic changes of African elephant milk composition over lactation
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Date
2018-12
Authors
Kobeni, Sibusiso
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
Taxonomically the Eutheria clade is split into mainly two groups: the Euarchontoglires, the well-known mammals, and the Atlantogenata, with the Elephantidae family. Like all mammals, the Atlantogenata produce milk with nutrients for growth and development of their neonate. However, the milk of elephants is hardly comparable with the milks of the Euarchontoglires, and it is unknown whether this is typical of Atlantogenata. Elephant milk has been studied for the past half-century, and unique properties are still being discovered. Some elephant milk nutrients are unique, and changes over lactationmmakes it impossible to define a typical elephant milk composition. The current research has shown that African elephant lactation may be divided into
three stages: the colostrums of two or three day’s post-partum, a twelve-month period of constant milk composition change, and mature milk thereafter until the end of lactation. The specific changes in milk composition of the individual elements of African elephant milk over lactation were observed to follow a particular trend. The milk density was almost constant over lactation. The milk ash and content of the major minerals, Na, K, Mg, P and Ca, increased over lactation. Vitamins were present in low concentrations, and increases over lactation might be dependent on the milk fat content. Vitamin E occurred in quantifiable amounts, with traces of vitamins A, D3 and K. The total protein content of African elephant milk increased with progressing lactation, with caseins as the predominant protein fraction. The milk carbohydrates of African elephant consisted of high amounts of lactose, isoglobotriose and oligosaccharides. The total carbohydrates steadily decreased over lactation, with the oligosaccharides becoming the major fraction, due to the decrease of lactose, which reached an equal level as isoglobotriose. The milk fat of African elephant increased with advancing lactation. The total content of saturated fatty acids changed from 72 % in colostrums up to 96 % after 19 months of lactation. The fatty acids of 10 carbons in length and shorter, increased during lactation, while those of 14 carbons and longer decreased, while lauric acid (12:0) expressed little change. These changes occurred in two phases; drastic changes from day zero to 9 months, and slow changes thereafter. The fatty acid composition of the phospholipids fluctuated throughout lactation. The phospholipids of medium-chain fatty acids were present in low concentrations, compared to the triacylglycerides, while long-chain fatty acids were present in high concentrations. The sterols also showed a fluctuating trend, perhaps following the fluctuation of the phospholipid fatty acids. Because milk secretion of the elephant is stimulated by suckling, it is possible that these fluctuations might be linked to the restoration of the milk secretion cell membrane after secretion. The energy levels of African elephant did not change much in the first ten months of lactation but increased thereafter due to the increase in protein, fat, and saccharides. Theoretical energy calculations were twice that of the experimental ones. The calculation formula, which was designed for milk with a nutrient content within the same order of magnitude as domesticated mammals and humans, seemed not suitable for the unique nutrient properties of the African elephant.
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Keywords
Dissertation (M.Sc. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2018, Milk, Elephants, Properties, Nutrients, Elephant milk composition