Impact of heat stress on health and performance of dairy animals: A review

Abstract

Sustainability in livestock production system is largely affected by climate change. An imbalance between metabolic heat production inside the animal body and its dissipation to the surroundings results to heat stress (HS) under high air temperature and humid climates. The foremost reaction of animals under thermal weather is increases in respiration rate, rectal temperature and heart rate. It directly affect feed intake thereby, reduces growth rate, milk yield, reproductive performance, and even death in extreme cases. Dairy breeds are typically more sensitive to HS than meat breeds, and higher producing animals are, furthermore, susceptible since they generates more metabolic heat. HS suppresses the immune and endocrine system thereby enhances susceptibility of an animal to various diseases. Hence, sustainable dairy farming remains a vast challenge in these changing climatic conditions globally.

Impact of the Egyptian summer season on oxidative stress biomarkers and some physiological parameters in crossbred cows and Egyptian buffaloes

“…Regarding the respiratory rate (Table-3), there was no significant difference between species and both species attended the highest respiratory rates in the last week prepartum which is compatible with the results of THI and RT. HS significantly affected respiratory rate (breaths/min) when compared to normal values (76.8 and 77.8 vs. 40-50) for cow and buffalo, respectively, as presented by Das et al [26]. According to Dalcin et al, respiratory rate can be a relevant physiological indicator for HS [27].…”

“…There is a very high positive correlation between the respiratory rate and ambient temperature. The increase in breathing rate (panting) sharply increases the loss of CO 2 through pulmonary ventilation with upsetting the critical balance of carbonic acid to bicarbonate excretion causing respiratory alkalosis [26]. In cattle under heat load, about 15% of the endogenous heat is lost directly from the body core through the respiratory tract [28].…”

“…In cattle under heat load, about 15% of the endogenous heat is lost directly from the body core through the respiratory tract [28]. HS that is characterized by elevated respiratory rates and RTs has been implicated in impaired metabolism and in poor reproductive performance in dairy cattle as well as in dairy buffaloes [26,29] independent of any effects on feed intake. The results of regression analysis between cows and buffaloes RTs and DMIs are presented in Figures-2 and 3, respectively.…”

Impact of heat stress and hypercapnia on physiological, hematological, and behavioral profile of Tharparkar and Karan Fries heifers

“…Similar results were reported by Indu [12] in Tharparkar and KF calves when the calves were exposed at 44°C for 4 h in a climatic chamber. Das et al [13] reported that air temperatures above 20-25°C in temperate climate and 25-37°C in a tropical climate such as in India, enhance heat gain beyond that lost from the body and induce HS which results into increased body surface temperature, RR, heart rate, and RT which leads to decrease in feed intake, production, and reproductive efficiency of animals. Similar findings were reported in Holstein Friesian and Brown Swiss cattle when cows were exposed to 0.45% of CO 2 level [6].…”

Climate Change Impacts and Adaptation in Florida’s Agriculture

“…Rising temperature can increase heat stresses, illness, diseases, and mortality, which subsequently reduce the productivity of livestock (Na rdone et al 2010; R ojas-Downing et al 2017; Das et al 2016). Increased temperatures will promote the growth of some forage crops but decrease nutrient availability (Rojas-Downing et al 2017;IPCC 2007).…”