Effect of Heat Stress on Production and Reproduction Potential of Dairy Animals Vis-À-Vis Buffaloes

Abstract

Production and fertility of animals are greatly influenced by management of environment or climate.
Buffaloes, due to morphological, anatomical and behavioural characteristics express the signs of great
distress when exposed to work in hot weather. Thermo neutral zone is range of temperature and other
climate parameter within which healthy animal can maintain its normal body temperature with minimal
change in metabolic activity. There are many environmental factors which influence effective surface
temperature, air temperature, relative humidity, air movement and radiation from the sun or other sources.
The effect of heat stress is aggravated when it is accompanied by high ambient humidity. Temperature
humidity index is a simple index, which indicates the degree of heat stress on dairy animals which
incorporates the effect of climate parameters like, temperature and relative humidity. Heat stress is
negatively correlated with production and fertility parameter. Harmful effect of the heat stress is observed
by decline in the milk production, change in composition of the milk, change in growth rate etc. Increase
in THI simultaneously increases age at first calving, service period, dry period, calving interval, incidence
of silent heat and decreases conception rate, pregnancy rate, lactation length in females. Male reproductive
performances are also influenced by temperature. Increase in temperature, decreases sexual desire,
ejaculate volume, live sperm concentration, viability, motility, conception rate and fertility rate.
Environmental modification is a short-term strategy but can be applied very efficiently for mitigation of
heat stress on animals. Long term strategy may include the requirement of genetic tolerant animals by
selection of animals in heat stressed conditions and through introgression of heat adaptation genes from
local adaptive breed in to non-adaptive or less tolerant herd.