Hagiya Koichi, Bamba Ikumi, Osawa Takefumi, Atagi Yamato, Takusari Naozumi, Itoh Fumiaki, Yamazaki Takeshi
Department of Life and Food Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
Data Analysis Division, National Livestock Breeding Center, Nishigo, Fukushima, Japan.
Anim Sci J. 2019 May;90(5):613-618. doi: 10.1111/asj.13186. Epub 2019 Feb 27.
We used daily records from provincial Japanese weather stations and monthly test-day records of milk production to investigate the length of the lags in the responses of cows' milk yield and somatic cell score (SCS) to heat stress (HS). We also investigated the HS thresholds in milk yield and SCS. Data were a total of 17,245,709 test-day records for milk and SCS in Holstein cows that had calved for the first time between 2000 and 2015, along with weather records from 60 weather stations. Temperature-humidity index (THI) values were estimated by using average daily temperature and average daily relative humidity. Adjusted THI values were calculated by using temperature, relative humidity, wind speed, and solar radiation. The model contained herd, calving year, month of test day, age group, days in milk, and THI as a fixed effect. THIs for each day from 14 days before the test day until the test day were used to represent the HS effects. The HS occurring 3 days, and between 8 and 10 days, before the test day had the greatest effect on the milk yield and SCS, respectively. The threshold THI values for the HS effect were about 60-65 for both traits.
我们利用日本省级气象站的每日记录以及牛奶产量的月度测定日记录，来研究奶牛产奶量和体细胞评分（SCS）对热应激（HS）反应的滞后时长。我们还研究了产奶量和SCS中的热应激阈值。数据包括2000年至2015年间首次产犊的荷斯坦奶牛的17,245,709条牛奶和SCS测定日记录，以及60个气象站的气象记录。利用日平均温度和日平均相对湿度估算温度湿度指数（THI）值。通过使用温度、相对湿度、风速和太阳辐射来计算调整后的THI值。该模型包含牛群、产犊年份、测定日月份、年龄组、泌乳天数和THI作为固定效应。从测定日前14天到测定日的每一天的THI值用于表示热应激效应。测定日前3天以及8至10天出现的热应激分别对产奶量和SCS影响最大。两种性状的热应激效应阈值THI值约为60 - 65。
