Heat stress affects ruminants, what about your production losses?

Heatstress impact

Heat stress can cause reduced rumen function and lower feed intake, which leads to a reduced energy supply and impacts dairy performance. Milk yield and milk components are reduced. Milk loss is linked to both heat stress levels and duration of exposure. Lallemand Animal Nutrition developed a more precise categorization of losses thanks to several scientific publications that represent different situations all around the world. For dairy cows, the common threshold used by the scientific community was 68 (Burgos and Collier. 2013). However, practical field studies show that heat stress can impact dairy cattle starting at a temperature-humidity index (THI) of 62. Hammani (et al., 2013), studied heat stress in northern Europe and defined that heat stress can impact cows at 62. Bourraoui (et al., 2002) found higher losses in milk, fat and protein yields in Mediterranean regions.

Check out the map

Temperature (째C 째F)
& Humidity (%)

FROM

17.2°C (63°F)

TO

21.7°C (70°F)

50%

FROM

22.7°C(72°F)

TO

25°C (77°F)

50%

FROM

25.6°C(78°F)

TO

30.6°C(87°F)

50%

ABOVE

31.1°C (88°F)

50%

THI
Tresholds

< 62

No stress

62-67

Low Stress

68-72

Mid-moderate Stress

73-79

Mild Stress

> 80

Severe stress

62

72

79

80

Range of performance losses due to heat stress

Milk yield

-1.0 ; -2.1 kg/day

Milk
fat (%)

-

Milk
protein (%)

-

Milk yield

-3.0 ; -5.5 kg/day

Milk
fat (%)

-0.1

Milk
protein (%)

-

Milk yield

-4.9 ; -7.8 kg/day

Milk
fat (%)

-0.3

Milk
protein (%)

-0.2

Milk yield

-6.6 ; -9.8 kg/day

Milk
fat (%)

-0.5

Milk
protein (%)

-0.4

Temperature (째C 째F)
& Humidity (%)

Below

25°C (77°F)

50%

FROM

25.6°C(78°F)

TO

28.9°C(84°F)

50%

FROM

29.4°C(85°F)

TO

32.8°C (91°F)

50%

ABOVE

32.8°C (91°F)

50%

THI
Tresholds

< 72

No stress

73-77

Mid-moderate stress

78-82

Mild stress

> 82

Severe stress

62

77

82

100

Range of performances losses due to Heat Stress

Daily gain

-60 ; -90 g/day

Daily gain

-120 ; -160 g/day

Daily gain

-130 ; -170 g/day

Daily gain

- 220 ; -250 g/day

Temperature (째C 째F)
& Humidity (%)

Below

23.3°C(74°F)

50%

FROM

24.4°C(76°F)

TO

25.6°C(78°F)

50%

FROM

26.1°C(80°F)

TO

28.9°C(84°F)

50%

ABOVE

28.9°C (84°F)

50%

THI
Tresholds

< 70

No stress

71-73

Mid-moderate stress

74-77

Mild stress

> 77

Severe stress

62

74

77

100

Range of performance losses due to heat stress

Milk yield

-0,22 kg/day

Dairy sheep

-0,13 kg/day

Dairy goat

Milk yield

-0,57 kg/day

Dairy sheep

-0,32 kg/day

Dairy goat

Milk yield

-0,87 kg/day

Dairy sheep

-0,59 kg/day

Dairy goat

Milk yield

-1.19 kg/day

Dairy sheep

-0,92 kg/day

Dairy goat

Look at the productionlosses due to heat stress in your region

As temperatures are rising, heat stress is a common and growing concern in ruminant production and experts are now fully aware that it is not limited to two summer months or tropical regions. Heat stress could be an issue for long periods. Cattle naturally change their behavior to help alleviate stress, which can disrupt digestion, increase inflammation, reduce performance, and impact their health.

To look at the THI values and impact on performance, select the location and species

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Look for visible signs to use strategies to help alleviate heat stress Strategies can include barn management or nutritional changes.

Specific nutritional strategies allow you to help mitigate the impact of heat stress.

Discover how to help reduce the impact of heath stress thanks to Lallemand Animal Nutrition's multi-solutions approach.

Learn More

The following signs can indicate poor rumen function

  • Decreased lying and rumination time.
  • Increased respiration rate and loss of saliva through panting.
  • Reduction in meal frequency and a larger meal size also known as "slug feeding".
  • Manure color and consistency can be affected: Undigested grain or cotton seeds, for example, are signs of sub-optimal rumen function, where precious (and expensive) nutrients are not being fully digested by the animal.
  • Lameness can be a sign of poor rumen function and Sub Acute Ruminal Acidosis (SARA) events. Heat stress can exacerbate poor rumen fermentation and function and negatively affect animal behavior, resulting in even worse locomotion scores and higher incidence of lameness.

These can also have longer-term impacts due to poor rumen function or increased oxidative stress

  • Negative effects on animal health, immune defenses and reproductive performance.
  • Impact on meat quality.