Articles
EFFECTS OF RADIATION SHIELDS AND CONDUCTIVE COOLING TO REDUCE HEAT STRESS IN DAIRY CATTLE
Article number
1008_37
Pages
279 – 285
Language
English
Abstract
Because dairy cows normally spend from 10 to 12 hours a day reclining, their physical comfort, and consequently the design of the stalls in which they recline, becomes important to the cows overall health.
In hot seasons, then, temperature becomes the key factor affecting milk production and disease among dairy cows.
At present, to reduce heat exposure and cool overly heated cows, dairy farmers rely mainly on shade roof/screens (i.e., radiation shields) of several types, and they also employ various forms of forced convection and evaporative cooling systems.
The effects that radiation-caused heat stress can have on a cow sheltering during the day under an un-insulated roof/screen can be significant in hot regions; however, only a few studies have attempted to find ways to reduce radiation levels even though it may be a large component of the heat load during hot-weather conditions.
For example, on a sunny day in Arizona, USA, an un-insulated roof can be as much as 20°C hotter than the ambient temperature, and the influence of the extra heat radiating from this roof can be significant.
As an alternative to existing types of cooling systems used to augment the effects of shade, we propose a potentially better solution to the problem, we propose a conductive cooling method that employs heat exchangers to reduce the temperature of the bedding material commonly used in dairy barns.
The heat exchangers would be placed under the bedding material on which the animal lies, and chilled water would circulate through the exchangers.
The purpose of this study, therefore, is to evaluate (i) the potential decrease in heat load to be achieved by insulating the barn roof and shade screens and (ii) the effectiveness of the proposed conductive cooling method.
In hot seasons, then, temperature becomes the key factor affecting milk production and disease among dairy cows.
At present, to reduce heat exposure and cool overly heated cows, dairy farmers rely mainly on shade roof/screens (i.e., radiation shields) of several types, and they also employ various forms of forced convection and evaporative cooling systems.
The effects that radiation-caused heat stress can have on a cow sheltering during the day under an un-insulated roof/screen can be significant in hot regions; however, only a few studies have attempted to find ways to reduce radiation levels even though it may be a large component of the heat load during hot-weather conditions.
For example, on a sunny day in Arizona, USA, an un-insulated roof can be as much as 20°C hotter than the ambient temperature, and the influence of the extra heat radiating from this roof can be significant.
As an alternative to existing types of cooling systems used to augment the effects of shade, we propose a potentially better solution to the problem, we propose a conductive cooling method that employs heat exchangers to reduce the temperature of the bedding material commonly used in dairy barns.
The heat exchangers would be placed under the bedding material on which the animal lies, and chilled water would circulate through the exchangers.
The purpose of this study, therefore, is to evaluate (i) the potential decrease in heat load to be achieved by insulating the barn roof and shade screens and (ii) the effectiveness of the proposed conductive cooling method.
Authors
C.Y. Choi , M. Mondaca
Keywords
conductive cooling, dairy cow, heat stress, radiation shield
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