Scrotal thermographic profile and seminal characteristics of Mangalarga Marchador stallions bred in the Atlantic Rainforest biome

S.V Matarazzo,P.P.N Snoeck,C.H.S.C Barros,W.M Machado

doi:10.1590/1678-4162-12165

Abstract

ABSTRACT The objective of this study was to determine the scrotal thermographic profile and to verify the influence of temperature and humidity of the humid tropical climate on testicular temperature and seminal quality of Mangalarga Marchador stallions. The thermal profiles of the proximal, middle, and distal zones of the testicles and total surface temperature (TSTT) were recorded using an FLIR E60bx thermal imager. The average air temperature (°C) and relative humidity (%) were obtained 1, 5, 9, 33, and 66 days before semen collection and showed a mean value of 26.5±2.4 and 80.4±6.0 respectively. The scrotal surface temperature was close to 34°C and there was no variation with the age of the stallion, reproductive activity, and characteristics of the ejaculate (P>0.05). The only significant correlations obtained were between TSTT and minor defects (R = 0.41; P<0.05), between TSTT and total defects (R = 0.46; P<0.01), and between TSTT and percentage of morphologically normal sperm (R = -0.46; P<0.05). It was concluded that the Mangalarga Marchador stallions maintained the testicular temperature within favorable conditions for spermatogenesis, demonstrating the efficiency of testicular thermoregulation mechanisms in the Atlantic Forest biome.

Highlights

Climate change and global warming trigger changes in air temperature, relative humidity, and precipitation, providing thermal stress that implies serious consequences for animal health and welfare (Lacetera, 2019)
It was concluded that the Mangalarga Marchador stallions maintained the testicular temperature within favorable conditions for spermatogenesis, demonstrating the efficiency of testicular thermoregulation mechanisms in the Atlantic Forest biome
Forty-three Mangalarga Marchador stallions were divided into different categories: 1) age, subdivided into males up to six years old, seven to years old, and over years old; 2) sexual condition, subdivided into males in reproductive activity or sexual rest during the breeding season; 3) characteristics of sperm subdivided when presenting progressive motility greater or less than 60% and with a percentage of morphologically normal sperm greater or less than 70%, to determine whether the scrotal thermographic profile could influence or be modified in any of these animal categories

Summary

Introduction

Climate change and global warming trigger changes in air temperature, relative humidity, and precipitation, providing thermal stress that implies serious consequences for animal health and welfare (Lacetera, 2019). Thermal insults on the scrotum result mainly from heat waves, which directly affect the spermatogenesis cycle, because the mechanisms involved in maintaining scrotal temperature begin to fail under conditions of thermal stress for several consecutive days (Lees et al, 2019). Most testicular problems are related to individual’s incapacity to maintain testicular temperature within physiological parameters. The increase in testicular temperature may induce testicular degeneration and loss of germline cells via apoptosis or necrosis, with impaired male fertility (Vieira et al, 2018). Digital infrared thermography stands out for being a non-invasive, non- stressful, and painless diagnostic technique to monitor animal scrotal surface temperature. It is described as complementary to andrological examination in horses and various other species (Kastelic et al, 1996; Ramires-Neto et al, 2013; Lloyd-Jones et al, 2015; Menegassi et al, 2017; Ahirwar et al, 2018)

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