General Knowledge About Heat Stress
The effects of heat stress on livestock health and production.
Thermocomfort Zone
Every animal species has its own thermoneutral zone within which the body can maintain normal body temperature with minimal energy expenditure. When the environmental temperature rises above this zone, the animal experiences heat stress.
The heat stress threshold varies by species and individual. High genetic potential, intensively producing animals are particularly sensitive, as their metabolism generates significant heat.
Observable Effects
Behavioral Changes
Animals eat less, drink more, seek shade, and reduce their physical activity. In cattle, increased panting and salivation are typical.
Increased Respiratory Rate
Elevated respiratory rate is one of the earliest signs of heat stress. Animals try to reduce their body temperature through respiratory evaporation.
Immune System Impact
Heat stress weakens the immune system, increases the risk of infections and reduces vaccine efficacy. Deterioration of intestinal mucosal integrity poses additional health risks.
Reproductive Consequences
Heat stress significantly impairs fertility: it reduces embryo viability, sperm quality, follicular development and implantation success. Signs of estrus become weaker or remain hidden.
Long-term Effects
Chronic heat stress causes lasting production losses: reduced milk yield, daily weight gain and egg production. Feed efficiency deteriorates, mortality rates increase, and animal lifespan may be shortened.
Impact on Offspring
Heat stress during gestation adversely affects offspring development: lower birth weight, weaker immune system and reduced future production potential characterize affected populations.
Climate Change and Future Risks
According to climate change projections, the number of heat stress days may increase by up to 25% in temperate regions over the coming decades. This means that heat stress management is not just a summer problem, but a strategic issue that every livestock farmer must prepare for.