Heat Stress

This summer we are working with Lallemand Animal Nutrition and Trouw Nutrition to monitor the risk of heat stress on several dairy farms in Southern England. Unlike previous work we will be assessing the risk of heat stress for both housed and grazing animals. This will also be the first time that the heat stress results are being reported in ‘real time’ to show the current risks.

A summary of the stress results are on the Lallemand website. We are tracking heat stress on a network of farms across the south of England as shown in the map. Use the links below the map to see the full set of results for each farm. The detailed dashboards start with coloured dials showing the current short term (3h average) and long term (24h average) heat stress index. If the short term index is high then there will be changes in cow behaviour, such as shade seeking, reduced appetite, increased standing, panting etc. If the longer term, 24h Index is high then the animals are not able to ‘recover’ overnight and the stress will accumulate with bigger impacts on milk yields and fertility. The temperature and humidity (over 5 days) is shown next and then the long term trends in heat stress index.

AssessmentEst. milk yield loss (l/day)THI ScoresDHLI Scores
None0under 62under 23
Moderate0 to 262 to 7223 to 36
High2 to 473 to 7937 to 46
Severeover 4over 79over 46
Lallemand Animal Nutrition
Trouw Nutrition
Farm Locations
AHartpury, GlosHoused THIGrazed DHLI
BHorsham, SussexHoused THIGrazed DHLI
CDorchester, DorsetHoused THIGrazed DHLI
DReading, BerksHoused THIGrazed DHLI
EAxminster, DevonHoused THIGrazed DHLI
FTrowbridge, WiltsHoused THIGrazed DHLI
GFareham, HantsHoused THIGrazed DHLI