Seasonal Variation in Milk Quality and Somatic Cell Count of Friesian Crossbred Cows in Southern Highlands, Tanzania

Seasonal variations in environmental conditions and forage availability can substantially influence milk composition and udder health, yet information from dairy production systems in the Southern Highlands of Tanzania remains limited. This study evaluated the effects of season on physicochemical milk quality parameters and somatic cell count (SCC) in Friesian crossbred cows managed under a semi-intensive production system at the Tanzania Livestock Research Institute (TALIRI) Uyole Dairy Farm. A total of 640 milk samples were collected from 20 cows during the rainy and dry seasons of 2024 and analyzed using an ultrasonic Lactoscan milk analyzer. Linear mixed-effects models were used to assess the effect of season while accounting for repeated measurements on individual cows. Milk fat content and freezing point were significantly higher during the dry season, whereas electrical conductivity and log-transformed SCC were significantly higher during the rainy season, indicating poorer udder health and reduced milk hygiene during periods of increased moisture. Protein, lactose, and solids-not-fat contents did not differ significantly between seasons. These findings demonstrate that seasonal environmental conditions substantially influence milk quality and udder health in semi-intensive dairy systems and highlight the importance of season-specific management strategies to improve milk quality and reduce the risk of subclinical mastitis in tropical dairy production.