Evaluating the impact of heat stress on milk quality in South Korea

Abstract

Context The probability of heat stress in South Korea is gradually increasing as a consequence of climate change. Although it is known that heat stress drives persistent negative effects on the lactation of dairy cattle, there is a lack of research on the effects of heat stress on milk quality in South Korea. Aim The aim of this study was to measure the influence of the temperature–humidity index (THI) on milk quality. Methods A non-parametric regression model was used to measure the influence of the THI on milk fat and milk protein. The data used in the model were obtained from observations of farmers’ management practises. Key results The concentrations of fat and protein in milk decreased when the THI was >65. In comparison with milk fat, milk protein was more significantly affected by heat stress. Conclusions A comparison of the THI values from 2001–2009 and 2010–2020 indicated that heat stress has occurred more frequently over time in South Korea. The concentrations of fat and protein in milk decrease when the THI exceeds 65. Implications Korean dairy farmers should build facilities that provide the optimal low and relatively dry conditions needed for dairy cattle to cope with heat stress and mitigate its impact on milk quality.