Changes in donkey milk lipids in relation to season and lactation

• Donkey milk quality during lactation and production season was investigated.
• Fat percentage and the diameter of milk fat globules were stable during lactation.
• Short chain fatty acids decreased whereas monounsaturated increased during lactation.
• In winter milk, a larger diameter of the globules, and a lower number/mL were found.
• Lower short chains and saturated were found in winter.

In this study the fatty acid profile and morphometric characteristics of fat globules in Amiata donkey milk in relation to the lactation phase and production season have been evaluated. Individual donkey milk samplings were carried out monthly starting from day 30 of lactation until day 300. The amount of fat and the diameter of the milk fat globules were fairly stable during lactation, whereas the number of globules/mL of milk decreased significantly only in the last phase of lactation. The fatty acid composition showed only few changes during lactation, which consisted in a progressive decrease in the short chain fatty acids and an increasing trend in the monounsaturated fatty acids. Winter milk showed a significantly larger average diameter, a lower number of fat globules/mL, lower (P < 0.01) percentages of short-chain saturated fatty acids and more (P < 0.01) long-chain and monounsaturated fatty acids. In addition, significantly lower percentages of C18:0 and higher of palmitoleic, oleic and vaccenic acids were detected in the cooler season. In conclusion the lipid fraction of donkey milk did not show notable changes during lactation.