Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Chronic stress in the dairy cattle industry has negative impacts on animal health, productivity, and welfare. It has been confirmed that cortisol transfers to milk and resists the high temperature during milk processing. This study evaluated the relationship between the milk cortisol concentration (MCC) in commercial milk products and the temperature-humidity index (THI) at the time of milk production. Eleven commercially produced pasteurized and sterilized milk products, purchased in Chuncheon, Korea, with production dates ranging from July to October 2021 were analyzed. The MCC was extracted using diethyl ether and analyzed using an enzyme immunoassay. The average THI values based on microclimate data provided by the Korea Meteorological Administration were 77 ± 0.8, 75 ± 1.4, 69 ± 1.4, and 58 ± 1.8, in July, August, September, and October, respectively. The average MCC levels were 211.9 ± 95.1, 173.5 ± 63.8, 109.6 ± 53.2, and 106.7 ± 33.7 pg/mL in July, August, September, and October, respectively. The MCC in July was higher than in August, September, and October (p < 0.05), while it was lower in September and October than in August (p < 0.05). Significant variations in the MCC were observed in commercial milk products across the four production months (p < 0.05), except for two milk products. Overall, monitoring the cortisol residue in commercial dairy milk products can be an alternative indicator of stress in dairy cattle of farms.

Relative humidity (RH%) data are inaccessible in the majority of cattle farms; however, such data often are available at local meteorological stations. Thus, this study purposed use of dry bulb temperature (DBT℃) data from a cattle barn and RH% data of Korea Meteorological Administration (KMA) for calculation of temperature-humidity index (THI). The scope of research was analysis of three cattle barns, categorized as barn 1 (sidewalls-closed and adjustable with windows, 1,071 ㎡), barn 2 (sidewalls-opened and adjustable with winch curtain, 1,067 ㎡), and barn 3 (sidewalls half opened, 544 ㎡) located at a livestock research farm at Kangwon National University. The microclimate data of the barns were recorded by Hobo loggers and compared with KMA data from June to September 2019. Comparison of maximum DBTºC between KMA and the barns showed no difference in the study period. On the other hand, minimum RH% at KMA was lower than those of barn1 and barn3 in June and September, and minimum RH% at KMA was lower than that of barn1 in August (p 0.05). The maximum THI based on KMA data was not different from that based on barns data. Moreover, the maximum THI based on KMA data was not different from that of modified THI (combination of maximum DBT℃ of barns and minimum RH% of KMA). Furthermore, maximum THI based on barns data was not different from modified THI of barns. The THI calculation in barns was correlated with KMA data. Overall, microclimate information from KMA can be used as effective barn microclimate data for THI calculation. We recommend using RH% data provided by KMA in the absence of microclimatic RH% data from a cattle barn as an effective way of regulating THI inside the cattle farm.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Chronic stress in dairy cattle industry has negative impacts on animal health, productivity, and welfare. It has been confirmed that cortisol transfers to milk and resists the high temperature during milk processing. This study evaluated the relationship between milk cortisol concentration (MCC) in commercial milk products and the temperature-humidity index (THI) at time of milk production. Eleven commercially produced pasteurized and sterilized milk products, purchased in Chuncheon, Korea, with production dates ranging from July to October 2021 were analyzed. The MCC was extracted using diethyl ether and analyzed using enzyme immunoassay. Average THI values based on microclimate data provided by the Korea Meteorological Administration were 77±0.8, 75±1.4, 69±1.4, and 58±1.8, in July, August, September, and October, respectively. The average MCC levels were 211.9±95.1, 173.5±63.8, 109.6±53.2, and 106.7±33.7 pg/mL in July, August, September, and October, respectively. MCC in July was higher than in August, September and October (p<0.05), while it was lower in September and October than in August (p<0.05). Significant variations in MCC were observed in commercial milk products across the four production months (p<0.05), except for two milk products. Overall, monitoring cortisol residue in commercial dairy milk products can be an alternative indicator of stress in dairy cattle of farms.