Effect of Somatic Cell Count on Milk Production, Composition, Colour, Coagulation Properties and Cheese-Making...

Somatic cell count (SCC) in milk is widely used as an indicator of intramammary infections in dairy sheep and is routinely monitored by the dairy industry as a marker of milk quality. This study aimed to evaluate the effect of SCC levels on milk production, composition, colour, coagulation properties, and cheese-making ability in Manchega dairy sheep. A total of 752 individual milk samples were analysed. To normalise SCC distribution, the somatic cell score (SCS) was calculated and samples were classified into SCS classes. Increasing SCS significantly reduced daily milk yield and lactose content, increased milk pH, and decreased lightness (L*). Higher SCS was also associated with impaired coagulation properties, including longer rennet clotting time (RCT) and curd firming rate (k₂₀), as well as reduced curd firmness (A₃₀, A₆₀). Similar effects were observed for modelled coagulation parameters, with delayed RCTeq and reduced kCF and CFp. Regarding cheese-making ability, SCS significantly affected curd humidity and protein recovery, whereas no significant effects were detected for dry curd yield or fat recovery. Overall, elevated somatic cell counts were associated with a reduction in the technological quality of Manchega sheep milk, particularly affecting coagulation behaviour and curd characteristics. These results underline the importance of controlling SCC levels in dairy sheep systems for both udder health monitoring and maintaining milk suitability for cheese-making.