1H nuclear magnetic resonance spectroscopy metabolomics of giraffe milk during mid- to late-lactation

Background: Dynamic changes in milk components during the end stages of lactation (involution) occur in all mammals. The time it takes to reach complete cessation may differ between taxa and species. The involution of cows, sheep, and goats (Bovidae) has been studied, but information on Giraffes is lacking. Objectives : Characterize the milk metabolome of giraffes at involution. Methods : Milk was obtained from five giraffes. Notably, all giraffes followed the same diet, a factor known to influence milk composition in domesticated mammals. Milk serum was prepared by filtration of the milk samples. A ¹ H-NMR metabolomics approach was followed, and statistical analysis of the data was done using MetaboAnalyst 6.0. Results : The changes in metabolites were characterized at 9.4, 12, and 15.1 months of lactation. Protein-type amino acids increased, while organic acids and lipid metabolites, as well as carbohydrates and their derivatives, decreased. This indicated that the synthesis of amino acids and proteins was upregulated, while that of lipids and carbohydrates was downregulated. Energy-producing amino acids and citric acid cycle intermediates decreased, indicating a decrease in the availability of energy metabolites. Conclusions : Involution, along with the associated changes in the milk metabolome, in the giraffe may commence at 12 months of lactation, but it is final at 15 months.