Factors affecting the size, distribution, and number of fat globules in sheep milk

This study presents a detailed characterization of the native fat globule size, distribution, and number in 275 raw ovine milk samples, utilizing advanced laser diffraction particle size analysis. Milk samples were collected from two indigenous Italian sheep breeds (Comisana and Massese) originating from three farms in the Tuscany region. Statistical analysis was conducted using a linear mixed-effects model, followed by a parametric bootstrap approach. Parity was significant on all globule size traits, with a non-linear reduction in diameter as parity increased. Days in milk had a marginally negative effect on globule diameter and significant negative effect on number of globules normalized per unit mass of fat. Breed x Fat interaction was significant, with Comisana ewes exhibiting a sharp increase in globule number and a decrease in size with higher fat content. Increasing Mg levels correlated with smaller, more diverse globules. Elevated Cl levels were associated with larger globules, decreased specific surface area, and reduced globule number.