African Elephant Milk Short Saccharide and Metabolite Composition and Their Changes over Lactation

SIMPLE SUMMARY: Elephant milk composition differs from all other mammals. The changes of elephant milk composition throughout lactation are also unique. The milk components are synthesized by metabolic processes and leave traces of molecules that provide clues of how these processes are aligned or which of these processes become preferred. Previous research showed that, in elephant milk, a variety of milk sugars are produced during lactation, and the fat content increases over lactation. This was evidenced in the current research by high contents of metabolites of the relevant metabolic pathways. The metabolites also show that some of the pathways may become less or more active with the progression of lactation. ABSTRACT: Elephant milk composition is unique, as are its changes over lactation. Presented here is the milk non-dedicated metabolite composition of three African elephants. Their lactation times are overlapping and span day one to thirty months. Metabolites were identified and quantified by (1)H nuclear magnetic resonance spectroscopy. Lactose and short oligosaccharides are a large component of the metabolites, with lacto-N-difucohexaose I as the major oligosaccharide. These were followed by metabolites of lipids, amino acids, and the citric acid cycle. The content of lactose, lacto-N-difucohexaose I, 2′-fucosyllactose, and some unidentified oligosaccharides decrease over lactation, while that of difucosyllactose and other unidentified ones increase. The high content of glutamate, as a glucogenic amino acid, supported the uprated synthesis of saccharides by the milk gland cells. The content of succinate and choline increase over lactation, indicating higher energy expenditure and phospholipid synthesis during later lactation.