How to tackle heat stress?

It is well known that heat stress in dairy cattle has direct negative consequences for the health and well-being of the cow. However, there are also long-term consequences that are less obvious, but which do lead to health problems and economic damage. All the more reason to quickly recognize heat stress symptoms and act immediately. Sensors play a crucial role in this today.

?

When does heat stress occur?

A commonly used measure to indicate heat stress in cows is the temperature-humidity index (THI). The THI is based on a combination of the air temperature and the relative humidity. In cows, a mild form of heat stress occurs above a THI value of 68, see Figure 1. In practice, heat stress can occur as little as 20°C/68°F . With increasing heat stress, the animals show short-term signs such as an increased respiratory rate, reduced appetite, lower activity and lower milk production.

Damage to health and production

A reduced appetite with the risk of rumen acidification[1] and a decrease in milk production is often immediately visible. Less well known are the long-term consequences of heat stress. A period of heat stress in a pregnant cow also has an effect on the unborn calf. Calves from dry cows exposed to heat stress have a 0.5 to 5.7 kg (1,1 to 12,5 lbs) lower birth weight[2], see Figure 2. These calves also eat and drink less, which means that the animals grow and develop less well after birth.

It is not only the birth weight of these calves that is lower. In their productive lives, milk production in the first, second and third lactation is also at a lower level than daughters of cows that have not experienced heat stress during pregnancy, see Figure 3.

It is estimated that in the United States alone, environmental heat stress costs the dairy industry more than $1.5 billion in annual losses due to decreased productive and reproductive performance and increased morbidity and mortality of lactating cows[3].

?

Sensors detect heat stress levels

Preventing or reducing heat stress therefore pays off in both the short and long term. Timely detection and immediate action is crucial. Sensors play an indispensable role in this. For example, Nedap's cow monitoring system detects four levels of heat stress at group level: no heat stress, mild heat stress, severe heat stress and very severe heat stress. The heat stress calculation is updated in real time every 15 minutes. The dairy farmer can then immediately take preventive measures in the barn, such as turning on fans or a sprinkler system to cool the environment. Or make adjustments in, for example, rations, milking and grazing times. Even before the cows start expressing a reaction. A validation study on test farms has shown that such measures directly lead to a reduction in the heat stress level by at least one level. Early detection therefore has the advantage of being able to act quickly.

?

More info about heat stress detection with Nedap CowControl?

Would you like more information about heat stress detection with Nedap CowControl, Nedap's cow monitoring system? Or do you want to stay up to date with the latest technological developments in dairy farming? Go to the website or sign up for this newsletter.

[1] Source: Dutch Animal Health Service.

[2] Research by Laporta et al shows that calves from cows that have experienced heat stress are lighter at birth than calves from cows without heat stress.

[3] Source: Laporta et al Late-gestation heat stress impairs daughter and granddaughter lifetime performance