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 required to reach complete cessation may differ among 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 1H-NMR metabolomics approach was followed, and statistical analysis of the data was done using MetaboAnalyst 6.0.

RESULTS

The changes in metabolites were characterised 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, suggesting reduced availability of energy metabolites.

CONCLUSIONS

Involution, along with the associated changes in the giraffe's milk metabolome may commence at 12 months of lactation but is complete by 15 months.