Thermoregulation of Girolando cows during summertime, in Pernambuco State, Brazil

Ivalda De Albuquerque Lima,Adriana Guim,Gledson Luiz Pontes De Almeida,Christhiano Raphael De Albuquerque Borges,Marcelo De Andrade Ferreira,Marcilio De Azevedo

doi:10.4025/actascianimsci.v35i2.16591

Ivalda De Albuquerque Lima, Adriana Guim + Show 4 more

Open Access

https://doi.org/10.4025/actascianimsci.v35i2.16591

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Abstract

This work was carried out to evaluate the physiological thermoregulation responses of Girolando-breed dairy cows kept in feedlot during summertime. A total of 15 animals were used, belonging to three genetic groups: 1/2, 5/8 and 3/4 Holstein-Gir (HG), with five cows from each genetic group, distributed in a completely randomized design, in subplots. The physiological parameters were sweat rate (SR), respiratory rate (RR), epidermis temperature (ET) and coat surface temperature (CST), and were evaluated once a week, during nine weeks, from December 2009 to February 2010, totaling 135 observations. Throughout the experimental period, climatic data were recorded using an automated weather station, and later used to calculate the different thermal comfort indexes: THI (temperature-humidity index), BGHI (black globe temperature and humidity index) and RTL (radiant thermal load). 1/2 HG animals showed the highest SR and lowest RR, ET and CST of all three genetic groups, while 3/4 HG cows had the lowest mean SR and highest ET and CST. 5/8 HG cows had intermediate values for SR, ET and CST. Mean RR values did not differ between 5/8 and 3/4 HG cows. It was concluded that animals from genetic groups 3/4 and 5/8 HG showed greater sensibility to heat stress than 1/2 HG cows.

Highlights

Milk production in Brazil has undergone significant transformations as a result of the current worldwide economic reality, which aims to increase productivity by employing modern technologies, while abiding by principles of sustainability and animal wellbeing during production
The values of air temperature (Table 1) - average temperature (28.2°C) and mean high temperature (31.9°C) - were above the upper limit of the thermoneutral zone for lactating cows, which according to Yousef (1985) are between 5 and 25°C
It was observed that the black globe temperature (Bgt), with mean value of 32.1°C and maximum of 34.3°C was higher than the value of 29°C cited by Beede et al (1983) as the critical Bgt capable of interfering with performance of dairy cows

Summary

Introduction

Milk production in Brazil has undergone significant transformations as a result of the current worldwide economic reality, which aims to increase productivity by employing modern technologies, while abiding by principles of sustainability and animal wellbeing during production This new production model aims to minimize animal stress. The capacity of animals to withstand the thermal environments to which they are exposed is proportional to their ability to dissipate heat, especially by sweating, reducing respiratory evaporation. This is more adequate for tropical climate environments (HANSEN, 2004), given the intense radiation to which these animals are subjected most of the time (SILVA et al, 2007). This work was carried out to evaluate the physiological responses to heat stress of 1/2, 5/8 and 3/4 Holstein-Gir Girolando cows in feedlot, in summertime, and compare these genetic groups with regard to their adaptability to environmental conditions

Material and methods

Results and discussion

Conclusion