Minimize consequences of heat stress on dairy cows with natural complementation

  • 0

Minimize consequences of heat stress on dairy cows with natural complementation

Tags :

Category : Uncategorized

Heat stress is a major concern in the management of dairy herds which adversely impacts welfare, performances and farm profitability. Moreover, considering the global climate change – with an estimated average rise of temperature on earth, between 0.5 to 4.8°C by 2100 – the heat stress episodes should become more common in farms.

To measure heat stress, the best indicator remains the Temperature and Humidity Index (THI). Dairy cows struggle with heat stress when THI rises above 72 units. This level is reached, for example, from a temperature of 24°C and a humidity of 68% (see graph1).

Low heat stress

THI 68-71


Mild heat stress

THI 72-79


Mild to severe heat stress

THI 80-89


Extreme heat stress

THI 90-99



>THI 99


Graph1: Heat stress diagram for dairy cows, Burgos Zimbelman and Collier, 2011

Above a 72-THI, each unit of supplementary THI will cause a fall of 0.2kg of milk/cow.

In Northern Europe, heat stress situations may even occur below this gradient. For example, a recent study in Scotland following the performance levels of a dairy herd during several years shows a decrease in milk production from a 60-THI (Hill and Wall, 2014).


Multiple consequences of heat stress

Heat stress has different consequences on dairy cows:

  • Above 71 °F (22°C), voluntary feed intake decreases, deteriorated by high humidity (table 1). To compensate this feed intake fall, there is an increase in body reserve mobilization.
Feed Intake (%) Relative Humidity (%)
50 60 70 80
Temperature (°F) 68 100 100 99 99
71.6 98 97 97 96
75.2 96 95 94 93
78.8 94 92 91 89
82.4 91 90 82 86
86 89 87 85 83

Table 1: Voluntary feed intake decreases with raising temperatures and humidity (Garcia and Diaz-Royon, South Dakota University, 2014).

  • There is also a redistribution of blood to the periphery to maximize radiant heat dissipation, while vasoconstriction occurs in the gastrointestinal tract. As a result, the exchanges at intestinal level are impaired in both ways: there is less nutrient assimilation in blood and there are potential risks of damage of the intestinal barrier.
  • Besides, panting increases heart rate and the excretion of carbonic gas. To maintain blood pH animal eliminates bicarbonates through kidney, leading to a metabolic acidosis. Moreover, the reduction of salivation increases the risk of acidosis.
  • Another consequence is an important loss of electrolytes, through sweating.
  • Several studies show an increase of the anoestrus period after calving, for dairy cows suffering from heat stress, largely due to a lack of energy intake.
  • Heat stress during the dry period of dairy cows decreases calf birth weight and compromises the passive IgG transfer from colostrum and cell-mediated immune function of the calves during the pre-weaning period (Tao, 2012).

All these impacts are even amplified with high-potential animals, which are particularly sensitive to temperature and hygrometry variations.


Nutrition to fight heat stress impacts

Due to the wide variety of heat stress impacts, it is very difficult to solve it with a unique and single mode of action. Among the possible options, nutrition can play an important role.

The nutritional solution Axion®Thermoplus incorporated to feed was developed to act at the different levels impaired by hot weather in order to maintain animal performance, through three several ways:

  • To prevent the feed intake drop, Axion®Thermoplus, as a specific blend of feed ingredients (with selected plant extracts and aroma), supports dry matter intake. In fact, its active components stimulate the activity of the key enzymes which contribute to feed digestibility (amylase, lipase, trypsine, and chymotrypsin).
  • The management of the mineral fraction via the use of Axion®Thermoplus (DCAD, buffers) also contributes to boost the feed intake with a better balance of electrolytes needs. Plant extracts increase salivary production which gives supplementary help for buffering the diet.
  • Plant extracts are also active in the general metabolism regulation, with a reduction of the heart rate and body temperature of the animals.


Field trial results

Dairy farms:

CCPA Group made several trials testing several diets and nutritional solutions, in different countries. In each country, an increase in milk production during hot period was seen for the batches of animals supplemented with Axion® Thermoplus: from 0.5 to 3 litres more, depending on different parameters. Even in farm with existing cooling system (for example in Viet Nam), a gain was seen with Axion® Thermoplus. In the following table are summarized several field trials led with two batches of animals, in different countries worldwide.

Location Number of animals Cattle breed THI Milk –Control group Milk – Axion® Thermoplus group Difference P-value
France 54 Prim Holstein 72 31.2 32.4 +1.2 p<0.05
Viet Nam 178 Prim Holstein 82 24.2 25 +0.8 p<0.05
Viet Nam 39 Prim Holstein 82 24 25.05 +1.05 p<0.05
Mexique 44 Prim Holstein 72 37 39.05 +2.05
Turquie 20 Prim Holstein 80 28.4 30.19 +1.76
Hongrie 632 Prim Holstein 79 29.46 31.73 +2.27
Brazil 175 Zebu Cross 75 30.6 31.6 +1 p<0.05
Brazil 36 Zebu Cross 79 18 19.3 +1.3 p<0.01

Table 2: Improving milk yield during heat stress, CCPA Group, 2016

It is also possible to reduce the impact of heat stress for small ruminant production. Indeed, another test with goats leads to the same kind of results.


Fattening units:

For fattening bulls, trials were also led in Brazil. These experiments have shown better performance levels and feed conversion rates with Axion® Thermoplus.

Location Number of animals Weight at start (kg) ADG –Control group ADG Axion® Thermoplus group FCR – Control group FCR -Axion® Thermoplus group
Brazil 1600 470 1020 1236 9.86 8.17
Brazil 700 400 1775 1845 6.11 5.96

Table 3: Increasing growth during heat stress, CCPA Group, 2012

Of course, beside nutrition, it is strongly recommended to control and adapt housing conditions and cooling systems and to select the time of feed distribution.

In order to evaluate the risk level of heat stress in farms, CCPA GROUP has also developed for the producers a heat stress application for smartphones (Iphone and Android) entitled: ThermoTool™, which can be downloaded for free on Apple Store:  and Google Play: Thanks to this application, breeders can anticipate heat stress over 5 days and quickly adapt, if necessary, the management of their farm and the animal nutrition.



Ruminant Product Manager

CCPA Group

  • 1


The weapon to fight against heat stress for



Lactating sows are particularly Heat Sensitive. At more than 20-22°C, each degree reduces feed intake by 190 g/d, resulting in a reduction in milk production and piglet weight gain. In addition, body reserve mobilization will increase with a decrease in fertility, decreasing the subsequent litter size and increasing in the weaning to estrus interval ratio.

In Grower Pigs, especially during the Finisher Period, Heat Stress will reduce  Feed Intake and a reorientation of the metabolism which enhance Fatter Carcasses.

AXION THERMOCONTROL contains the plant extract Scutellaria baicalensis, reducing inflammation against heat stress


  • Improves FEED INTAKE of pigs during HEAT STRESS
  • Improves the DIGESTIBILITY of the feed via the action of specific plant extracts on ENZYMATIC ACTIVITY
  • Reduces RESPIRATORY RATE, resulting in less METABOLIC HEAT

TRIALS:  Lactating sows

  • Feed intake was 10% higher
  • Body weight loss was 9% less
  • More than 250 g improvement in piglet weight at weaning.

TRIALS:  fattening period

  • Increased feed intake
  • Fewer days necessary to reach market weights (4 days).
  • At the same time, carcass weight was increased by 2 kg and the meat quality was improved (leaner carcasses).

For More Information:

Contact Herman Mynhardt at 0744129640 or


Translate »