Avoid. Heat. Stress.

Rising outdoor temperatures also mean a higher risk of heat stress for herds on dairy farms. Due to climate change, heat stress is a growing problem even in moderate climate regions. Heat stress is an enormous burden for the animals, which can have dire consequences for productivity and animal health on your farm. With smaXtec, you can accurately detect heat stress and take immediate action to relieve the cows. The result: a healthier herd with stable milk yield and better fertility, resulting in less work and costs for your farm.

From the USA or Europe to Africa and Asia, weather authorities across the globe are expecting a significant increase in heat waves in the coming years, which may also be longer and hotter than before. While a day is commonly called a heat day when outside temperature exceed 30°C/90°F, the critical upper limit for cattle is already reached at around 25-26°C/78°F, which means that heat stress can quickly develop in dairy cows on hot summer days. ⁽¹⁾
Whether or not a dairy cow is experiencing heat stress depends greatly on weather conditions at the respective lovation, of course: While research suggests that in the US, the average dairy cow is exposed to 96 heat stress days per year, Florida has more than 250 heat stress days per year on average, scientists found. ⁽⁷⁾
Heat can become a real problem for dairy farms, as heat stress causes a reduction in milk quantity and milk quality in dairy cows, which can directly impact your bottom line. Animal health also suffers, as the significant circulatory stress caused by the heat can, in the worst-case scenario, lead to the death of the animal. ⁽¹⁾ Additionally, hot outside temperatures make oestrus detection more difficult and can cause increased calving problems, making it harder to manage herd fertility efficiently. smaXtec helps you intervene early in heat stress by measuring inside and outside to accurately detect signs of heat stress.

Detect heat stress earliest possible – with smaXtec.

All measurement data of the smaXtec Bolus are of great importance for the early detection of heat stress. Heat stress symptoms are recorded by the smaXtec Bolus individually for each animal and with the highest precision (±0,01°C/±0.018°F relative measurement accuracy):

• Increased temperature
• Decreased rumination
• Reduced activity
• Insufficient water intake

smaXtec calculates the group temperature based on individual temperature notifications to also detect changes at the group level and automatically notifies you of heat stress.

The group metric temperature is available in the smaXtec App as well as in the smaXtec Messenger and makes it even easier for you to detect slight changes in temperature as the curve diagram is shown in a narrower temperature scale (36-44°C/96-111°F) and without drinking cycles.

The smaXtec Climate Sensor measures outdoor temperature and humidity and, based on this, automatically calculates the THI (Temperature Humidity Index), which maps the probability of heat stress. If the THI is elevated, you are notified and can take immediate action to improve the climate inside the barn.

Heat stress can be measured using the temperature humidity index (THI). The THI is calculated with a formula that is composed of air temperature and relative humidity. Depending on the field of application, there are different ways to calculate the THI. At smaXtec we use the following formula:

THI=(1.8×T+32)−[(0.55−0.0055×RH) ×(1.8×T−26)]⁽²⁾

T = dry-bulb temperature (°C) und RH = relative humidity (%)

• THI ≥ 72: mild heat stress
• THI ≥ 78: moderate heat stress
• THI ≥ 82: severe heat stress

How does heat stress affect milk yield?

While some breeds of cattle are less susceptible to heat stress than others, the general rule is that the higher the milk yield, the more heat the cows produce. Therefore, high-yielding cows are more susceptible to heat stress than cows with lower milk production. Studies show that milk yield can decrease by about 16% to 30% in the current lactation due to heat stress. ⁽³⁾ Heat stress and insufficient cooling can have a negative effect on dry cows as well, as studies found that in the following lactation, heat stress can reduce milk yield by as much as 5kg/11 lbs per day on average. ^{(4) (7)}
Milk quality suffers, too: While the milk fat content decreases due to lower rumination activity and shorter lying times, the cell count in the milk increases because concentrated feed is preferred and too little basic feed is eaten. ⁽⁵⁾

How does heat stress affect animal health?

Dairy cows have difficulty coping with heat stress, which has a tremendous impact on productivity and animal health. Body temperature and respiratory rate often increase, and animals are less active and stand up more. ⁽³⁾ Such stress can cause the following problems, among others:

• Lower feed intake, increasing the risk of ketosis in high-performance animals.
• water shortage, as cows do not drink enough water even when there is sufficient supply
• prolonged heat leads to increased mastitis, foot problems and ruminal acidosis
• migration of pathogenic germs from the digestive tract (E. coli)

If the heat stress is very severe, much more serious problems can occur, leading to death in the worst case. ⁽³⁾

Water supply plays a special role in hot weather, because the higher the ambient temperature and milk yield, the greater the demand for water. While dry cows take in approximately between 43 liters/11.3 gallons (5°C/41°F) and78 liters/20.6 gallons (28°C/82°F) of water, depending on the outside temperature, dairy cows with a milk yield of 45 liters/11.8 gallons require approximately between 96 liters/25.3 gallons (5°C/41°F) and 132 liters/34.8 gallons (28°C/82°F) of water per day. (6)
These values can vary depending on the weight, milk yield and lactation day of each individual animal, but they make the importance of a good water supply very clear. With smaXtec, you have a full overview of the drinking behavior of all animals and can improve the water supply if necessary.

How does heat stress affect fertility?

In high heat, cows show less obvious and shorter signs of oestrus, which in some cases may be absent altogether. ⁽³⁾ Poorer oocyte quality caused by heat can also reduce the fertility performance of animals. ⁽⁵⁾
During the important transit phase, cows should receive special attention during heat stress, as symptoms such as decreased feed intake and the resulting energy deficit during the period near parturition can have a particularly negative impact on cow health. ⁽⁵⁾
With smaXtec health monitoring, you can detect both calving and typical subsequent diseases such as milk fever, displaced abomasum or retained placenta at an early stage, thus ensuring a good start to lactation.

Avoid consequences of heat stress

In addition to the immediate consequences of heat stress such as reduced milk yield, reduced oestrus and poorer health as a result of overheating, there may also be secondary diseases such as ketosis, rumen acidosis, mastitis or hoof problems after the disease has been overcome. ⁽³⁾ With smaXtec, farmers can take timely action against these consecutive symptoms and avoid negative consequences for herd health and farm success.

Sources:
(1) STÖBER, M., 2002: Hitzschlag/exogene Hyperthermie, in: Dirksen, G., Gründer H.D und Stöber M. (Hrsg.): Innere Chirurgie und Medizin des Rindes, Parey Verlag Berlin, Wien, 1163-1165
(2) https://www.journalofdairyscience.org/article/S0022-0302(08)71054-3/fulltext
(3) https://raumberg-gumpenstein.at/jdownloads/Tagungen/Nutztierschutztagung/Nutztierschutztagung_2014/3n_2014_gasteiner.pdf
(4) https://www.journalofdairyscience.org/article/S0022-0302(19)30357-1/fulltext
(5) https://raumberg-gumpenstein.at/forschung/forschung-aktuelles/hitzestress-in-der-rinderhaltung.html
(6) https://www.lfl.bayern.de/mam/cms07/ite/dateien/27910_wasser.pdf
(7) https://edis.ifas.ufl.edu/publication/AN342