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Study on the effect of heat stress in milk production traits of Korean Holstein cows
Journal of the Korean Data & Information Science Society 2018;29:241-9
Published online January 31, 2018
© 2018 Korean Data and Information Science Society.

SeokHyun Lee1 · Yunho Choy2 · Chang-Gwon Dang3 · Alarn Mahboob4 · Kwanghyun Cho5

1234National Institute of Animal Science, RDA
5Korea national College of Agriculture and Fisheries
Correspondence to: Professor, Korea national College of Agriculture and Fisheries, Jeollabuk-do 54874, Korea. E-mail:
Received November 8, 2017; Revised December 19, 2017; Accepted January 2, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The study was conducted to investigate the effect of heat stress on milk production traits. The temperature-humidity index (THI) was used to estimate the degree of heat stress and as an indicator of heat load. The meteorological data corresponding to test-day records were collected from 29 and 10 regional weather stations with automated surface observing system (ASOS) and automatic weather system (AWS) installed, respectively. A total of 156,989 test-day records on 23,947 dairy cows, between 2000 and 2016, was collected by two agencies (dairy cattle genetic improvement center and Korea animal improvement association). The analysis of variance estimates among 3 models showed significant differences between all environments and traits (p < 0.001). Results showed that milk fat and milk protein productions were decreasing with both increasing of THI and highest temperatures. However, the milk yield decreased only after a threshold of THI or highest temperature was exceeded. Our results suggested that the use of THI or highest temperature in dairy genetic evaluation could improve heat tolerance ability in Korean Holsteins.
Keywords : Heat load, heat stress, Korean Holstein, temperature-humidity index.