Heat Stress in Dairy Cattle: Major Effects and Practical Management Measures for Prevention and Control

Abstract

SOJ Veterinary SciencesOpen Access Review Article ways by which animals can get rid of their thermal body load: conduction, convection, radiation ( Figure 1). In the zone I-III the animal can maintain a constant body temperature; in zone I-II and zone II-III heat production and heat loss is regulated. In zone I-II, heat production increases in order to maintain homeostasis. Zone II-III is the thermo-neutral zone, where heat loss is kept constant. Factors other than climate (e.g. ration, milk yield level, activity) determine the heat production in that zone [2]. The temperature points II and III are the lower and upper critical temperatures respectively, beyond which cold stress and heat stress respectively occur.When temperature increases beyond a given critical limit, the non-evaporative ways of heat loss appear to be far less efficient. And if temperature rises even more, the cow changes from a non-evaporative to an evaporative way. However, the latter is strongly dependant on the level of air humidity.The thermo-neutral zone of dairy cows in full lactation is, roughly speaking, between -5°C and +20°C for adult dairy cows AbstractOver the past years we have experienced several periods of heat waves, sometimes of short, other times of longer duration. This phenomenon will, most probably, be more frequent in the years to come. Heat waves may have detrimental effects on cattle production, health, welfare and reproduction. The question is whether cattle farmers and even veterinarians are sufficiently prepared and instructed to counteract or, even better, prevent the negative effects of heat stress in their cattle. This paper reviews the most relevant issues associated with the occurrence of heat stress, and provides practical measures to counteract and prevent the negative effects of heat stress in cattle.

Temperature-Humidity Indices as Indicators to Heat Stress of Climatic Conditions with Relation to Production and Reproduction of Farm Animals

“…The decreased milk production during heat stress can be due to dwindled nutrient uptake by portal drained viscera of the cattle and decreased nutrient uptake [44]. It has been observed that milk yield starts declining by 0.2 kg for every unit rise in THI value above 72 [76]. There are further reports establishing the negative correlation between THI values and milk yield [65].…”

The Effects of Evaporative Cooling on Heat Stressed Dairy Holstein Cows Under a Semi-Arid Environment in Riyadh Area, Saudi Arabia

“…The summer months in the Riyadh region, Saudi Arabia, are characterized by high temperatures and low humidity. Lactating dairy cows prefer ATs of between 10 and 25°C, known as the thermoneutral zone [23]). Whenever AT is beyond these limits, cows are considered to be under heat stress, thus, milk production declines [24].…”

Study on Knowledge Level of Livestock Owners Related to Breeding Aspect of Organic Animal Husbandry Practices in Arid Region of Rajasthan

“…they follow in their farms. The results presented in Table 3, showed that majority (53.61) of livestock owners used natural service for animals [7]. Easy availability, no fees, no monitoring and high conception rate could be the reasons for adoption of natural service as compared to A.I.…”