Negative Effects of Heat Stress on Growth and Milk Production of Farm Animals

Optimal climatic conditions for cattle, buffaloes, sheep goats, rabbits and poultry would be something like an air temperature of 13 to 20 ºC, a wind velocity of 5 to 18 km/hr, relative humidity of 55 to 65% and a moderate level of sunshine and these factors are interrelated. In tropical and subtrobical countries, climatic characteristic is the major constraint on animal productivity. Growth, milk production and reproduction are impaired as a result of the drastic changes in biological functions caused by heat stress
The summer in Egypt is characterized by high ambient temperature, intense solar radiation and high relative humidity. Therefore, farm animals raised to such a sever climatic stress for almost 6 months of the year. Exposure of animals to heat stress evokes a series of drastic changes in the biological functions, which include a decrease in feed intake, feed efficiency and utilization, disturbances in water, protein, energy and mineral balances, enzymatic activities, hormonal secretions and blood metabolites ending to impairment the productive and reproductive performance.

Keywords: Farm animals, heat stress, growth, milk yield.