EFFECT OF HOTLY SUMMER IN ASSIUT ON HEALTH STATUS, PRODUCTIVITY AND BEHAVIOR OF FRIESIAN DAIRY CATTLE AND THE EVALUATION OF TRADITIONAL

S.A Kotb;,Madeha Darwish*,M.A Abdel-Rahman

doi:10.21608/avmj.2008.166868

Abstract

Thirty mid-lactation Friesian cows, 178 day post-partum were randomlyassigned to three equal groups (N= 10 per group). All animals wereblocked for age (6 year old), stage of milk yield and average bodyweight. The experiment was carried out during the months of July andAugust, 2007 in which the first group of the experimented- animal wasleft in loose box without shade and expressed to heat stress while thesecond group was left in shaded box (white galvanized metal roof, 4meters above the ground and covered about 70% of the yard area).However the later group left in a box supported with shade plus fans(fans were installed regularly at height of 2.4 meters above the groundand spaced 1.5 meters along the manger shed). Our study revealed thatprovision of shade had no significant effect on temperature-humidityindex (THI) while providing shade and fans had significantly loweredTHI. At the same time the shade and fans had a significant effect ondaily milk production but shade alone had no significant effect on milkyield. Milk yield was slightly increased with shade (insignificant) andtended to be greater for shaded and cooled cows (significant) as compareto non shaded animals. Also, this study indicated that, forage intake wassignificantly lower for the experimented cows that housed without shadethan for those housed with shade and fans. Providing dairy cows withaccess to shade or to shade and fans during summer season was effectivein reducing mean rectal temperature and respiratory rate. Moreover, thisstudy revealed some statistically significant differences in certainbehavioral patterns of cows that housed without shade under theprevalent hot weather and those housed either under shade only or undershade and fans (p < 0.01). Moreover, leucocytic series of theexperimented cows was not significantly affected by any of the studiedhousing conditions however cortisol and glucose levels weresignificantly higher (p < 0.01) in the serum of the experimented cows thathoused without shade than in those housed either with shade only orwith shade and fans.

Highlights

When European breeds of farm animals are introduced to tropical and subtropical countries, they are forced with many problems relating to the hot climate, that induced conditions of heat stress which caused by combination of environmental factors such as air temperature, relative humidity, solar radiation and wind speed
The previously mentioned data, showed that temperature-humidity index was higher than temperature -humidity index above critical thresholds accounted for heat stress (72) as stated by Armstrong et al (1988) during different housing condition, a finding which indicating the exposure of cows to heat stress during the summer season
Housing of dairy cows without shade was found to have an adverse effect on health, productivity and behavior

Summary

Introduction

When European breeds of farm animals are introduced to tropical and subtropical countries, they are forced with many problems relating to the hot climate, that induced conditions of heat stress which caused by combination of environmental factors such as air temperature, relative humidity, solar radiation and wind speed. When cow exposed to hot ambient temperatures, their respiration rate and body temperature will increase (Spiers et al, 2004) so, they adjust their behavior in an attempt to maintain thermal balance (Bennett et al, 1985 and Blackshaw and Blackshaw 1994). Fisher et al (2002) reported that the use of shade was necessary for dairy cows when ambient temperature exceeded 25oC and was effective in reducing animal temperature. Several studies have shown that cooled cows had lower rectal temperature and respiratory rates than non-cooled ones (Armstrong et al, 1985; Armstrong et al, 1988; Armstrong et al, 1993 and Chen et al, 1993)

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