Physiological parameters, hair coat morphological characteristics and temperature gradients in holstein-gyr crossbred cows

Patrícia Ferreira Fernandes Da Cruz,Camylla Pedrosa Monteiro,Mara Regina Bueno De Mattos Nascimento,Robson Carlos Antunes,Ednaldo Carvalho Guimarães

doi:10.14393/bj-v32n2a2016-29827

Patrícia Ferreira Fernandes Da Cruz, Camylla Pedrosa Monteiro + Show 3 more

Open Access

https://doi.org/10.14393/bj-v32n2a2016-29827

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Journal: Bioscience Journal	Publication Date: Jan 1, 2016
Citations: 6	License type: cc-by

Abstract

The aim of this study was to assess physiological parameters, hair coat morphological characteristics and temperature gradients in crossbred Holstein-Gyr cows in the municipality of Tapira, Minas Gerais (MG), Brazil. Forty-nine lactating cows from six Holstein (H) and Gyr (G) genetic groups (1/4H 3/4G, 3/8H 5/8G, 1/2H 1/2G, 5/8H 3/8G, 3/4H 1/4G and 7/8H 1/8G) were distributed in a completely randomized design. The dry-bulb temperature and relative humidity were recorded, and the temperature and humidity index (THI) was calculated. The rectal temperature, respiratory rate and body surface temperature were measured, as were hair thickness, numbers, length and angle. Cows with a greater than 50% Holstein breed ratio (5/8H 3/8G, 3/4H 1/4G and 7/8H 1/8G) showed a higher respiratory rate and greater hair length than animals with genetic composition equal to or greater than 50% Zebu (1/2H 1/2G, 3/8H 5/8G and 1/4H 3/4G). Animals from the 1/2 and 1/4 HG genetic groups showed the greatest hair angle (P<0.05). With respect to climatic characteristics, the examined locality was within the thermoneutral zone and therefore did not impose conditions of thermal stress. The animals exhibited thermoregulation and hair coat characteristics that were within physiological parameters.

Highlights

The selection of animals showing higher survivability, production and reproduction and knowledge related to the adaptability of breeds exploited under tropical environments is crucial to increase milk productivity in Brazil (FAÇANHA et al, 2013)
The effects of heat stress are more pronounced in animals with high metabolic rates, including lactating dairy cows (MARTELLO et al, 2004), whose genetics mostly derive from temperate regions
According to Brasil (2006), the best Minas cheese is produced in Minas Gerais state because this state has different geographical regions with specific characteristics conditioned by physical and natural factors that result in characteristic natural pastures and lead to the development of specific bacteria that multiply in each of these microclimates and give each cheese a specific appearance and taste

Summary

Introduction

The selection of animals showing higher survivability, production and reproduction and knowledge related to the adaptability of breeds exploited under tropical environments is crucial to increase milk productivity in Brazil (FAÇANHA et al, 2013). Changes in the respiratory rate and rectal temperature are related to the physiological response to stress (COSTA; SILVA et al, 2009). The effects of heat stress are more pronounced in animals with high metabolic rates, including lactating dairy cows (MARTELLO et al, 2004), whose genetics mostly derive from temperate regions. These animals are sensitive to temperature variations, leading to behavioral and physiological changes that cause reduced milk production (TOSETTO et al, 2014). It is important to provide thermal comfort to dairy cows to ensure their welfare and optimal production performance (PEREIRA, 2005)

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