Relationships between temperature-humidity index and the cheese-making potential of dairy milk in temperate environments

Abstract

Abstract In response to climate change, indoor stalling challenges, and the sensitivity of dairy cows to elevated temperatures (often initiated at THI > 68), previous research has primarily targeted the effects of elevated THI, creating a gap in knowledge regarding low THI. Yet, freezing winters still reduce milk quality and productivity of high-yielding cows. This study investigates the association between different THI classes (< 40, 40–70, and > 80) on the yield, composition, and technological properties of milk from temperate-climate dairy cattle by analyzing 867 records across two years from 338 healthy cows in three herds. THI classes were associated with milk yield and its adjusted yields ( p < 0.01, p < 0.05). Milk production was highest within THI 40–70. Fat-corrected milk (FCM) yield peaked under high thermal conditions (THI > 80, p < 0.01), whereas value-corrected milk (VCM) and laboratory curd yield significantly decreased as THI rose ( p < 0.01). THI did not affect coagulation time or visual quality scores. Somatic cell count (lnSCC) and free fatty acids remained stable across all groups. Therefore, temperate-climate breeding programs and immediate herd management strategies must mitigate these challenges. This should enhance cow resilience to THI extremes, which is crucial for high-yielding breeds like Holstein-Friesian.