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.
Assessment | Est. milk yield loss (l/day) | THI Scores | DHLI Scores |
---|---|---|---|
None | 0 | under 62 | under 23 |
Moderate | 0 to 2 | 62 to 72 | 23 to 36 |
High | 2 to 4 | 73 to 79 | 37 to 46 |
Severe | over 4 | over 79 | over 46 |

Identity | Location | ||
---|---|---|---|
A | Hartpury, Glos | Turned off | |
B | Horsham, Sussex | Turned off | |
C | Dorchester, Dorset | Turned off | |
D | Reading, Berks | Turned off | |
E | Axminster, Devon | Turned off | |
F | Trowbridge, Wilts | Turned off | |
G | Fareham, Hants | Housed THI | Grazed DHLI |