Heat stress and spermatogenesis in Bos indicus and Bos taurus cattle

Skinner, J. D.; Louw, G. N.

doi:10.1152/jappl.1966.21.6.1784

Cited by 111 publications

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“…Similar changes occurred at corresponding times in previous studies that involved increased testicular temperatures in bulls and rams (Howarth 1969;Meyerhoeffer et al 1985;Saab et al 2011;Rocha et al 2015;Hamilton et al 2016) with some apparent differences in the magnitude of changes and the interval from the thermal insult to recovery, attributed to the degree and duration of testicular heating and perhaps species-specific characteristics (Skinner and Louw 1966;Rathore 1970;Brito et al 2004;Nichi et al 2006). Furthermore, in this study, sperm damage occurred during the final stages of spermatogenic development in the testis (Howarth 1969;Cardoso and Queiroz 1988;Senger 2003).…”

Section: Discussionsupporting

confidence: 88%

“…In many mammals, including sheep, it is well established that testis must be 4-5 °C below core body temperature to sustain physiological production of sperm, and to ensure that it is produced in proper numbers, and with appropriate motility and morphology (Skinner and Louw 1966;Kastelic et al 1995;Saab et al 2011). Furthermore, the testis normally operates in a condition of near-hypoxia (Waites and Setchell 1964).…”

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confidence: 99%

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Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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ABSTRACT:The mammalian testis typically operates on the brink of hypoxia; the long-standing dogma is that increased testicular temperature increases metabolism, but blood flow is unaffected and the resulting hypoxia reduces sperm motility and morphology. In rats and mice, oxygen (O 2 ) content of inspired air affected O 2 content of testes, enabling the latter to range from approximately 50 to more than 200% of physiologic concentrations. A ram model was used to test the hypotheses that hypoxia would disrupt sperm motility and morphology and that hyperoxia would prevent hyperthermia-induced reductions in sperm motility and morphology. Eighteen Canadian Arcott rams (approximately 10 months old) were used in a 2 × 3 factorial, with factors being scrotal insulation (insulated or not insulated) and O 2 concentrations in inspired air (14, 21 or 85%). Six rams, three with and three without scrotal insulation, were placed in each of three enclosed areas for 30 h to expose them to their respective oxygen concentrations, with scrotal insulation removed at the end of the exposure. Semen was collected by electro-ejaculation twice before insulation, bi-weekly for four weeks starting one week after exposures, and then once weekly for two weeks. There were effects of insulation, time and an insulation × time interaction for motile sperm and sperm that had normal morphology or head or midpiece defects (P < 0.01 for each). Sperm motility and morphology exhibited alterations between approximately two and five weeks after insulation, with mean progressively motile and morphologically normal sperm decreasing from approximately 55 to 35% and from 80 to 30%, respectively, and with head and midpiece defects increasing from approximately 3 to 50% and from 10 to 20% (P < 0.05 for each). The hypotheses that hypoxia would disrupt sperm quality and production, whereas hyperoxia would prevent hyperthermia-induced reductions in sperm quality and production, were not supported. This is apparently the first report that heat-stress induced damage to sperm was due to increased temperature per se and not testicular hypoxia, calling into question a long-standing paradigm.

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Section: Discussionsupporting

confidence: 88%

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confidence: 99%

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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“…However, continuous exposure to temperatures higher than 30ºC can determine a marked negative effect on sperm production (SKINNER;LOUW, 1966). This situation occurred during the experiment, as temperatures reached 34.2ºC.…”

Section: Discussionmentioning

confidence: 99%

Efeitos da disponibilidade de sombra a campo sobre características reprodutivas de touros da raça Nelore (Bos indicus) criados na região Sudeste do Brasil

Tarragó

Rodrigues

Zaffalon

et al. 2013

Braz. J. Vet. Res. Anim. Sci.

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Solar radiation is responsible for bull body temperature elevation. An alternative to minimize heat stress is to use artificial shade. Thus, this study aimed to evaluate the effect of thermal stress reduction, through shade availability, on reproductive characteristics of Nellore bulls (Bos indicus). For this, ten bulls were divided in: Available artificial shade (AS, n = 5) and Unavailable shade (US, n = 5). Each group was kept in two hectare paddocks, in which shade availability for group AS was artificially created. Animals were submitted to a clinical-reproductive evaluation and seminal analyses. No interaction was observed between treatments (AS and US) and time (8 collections) for all analyzed variables (P>0.05). No significant effect (P > 0.05) of treatment was observed for all parameters analyzed. So, it can be concluded that the absence of shaded areas during summer does not negatively affect reproductive characteristics such as: scrotal circumference, testicular consistency, progressive motility, percentage of rapidly moving cells (Computer Assisted Semen Analysis -CASA), morphology or sperm viability in Nellore bulls raised in southeastern Brazil, considering that results could be different in other regions of the country where average temperature is higher. Keywords:Semen. Artificial shade. Nellore. Bull. ResumoA radiação solar é responsável pelo aumento da temperatura corpórea em touros. Uma alternativa para minimizar o estresse térmico é usar sombreamento artificial. Assim, este estudo teve como objetivo avaliar o efeito da redução do estresse térmico através da disponibilização de sombra artificial, sobre características reprodutivas de touros da raça Nelore (Bos indicus). Para isso, dez touros foram divididos em: Disponibilidade de sombra artificial (AS, n = 5) e Não-disponibilidade de sombra artificial (US, n=5). Cada grupo foi mantido em piquete de dois hectares cada, no qual a sombra para o grupo AS foi criada artificialmente. Os animais foram submetidos a avaliações clínicas-reprodutivas e análise seminal. Nenhuma interação foi observada entre os tratamentos (AS e US) e o tempo (8 coletas), para todas as variáveis analisadas (P > 0.05). Nenhum efeito significativo (P>0.05) de tratamento foi observado para os parâmetros analisados. Dessa forma, concluiu-se que a ausência de áreas sombreadas, durante o verão, não afetou negativamente as características reprodutivas como: circunferência escrotal, consistência testicular, motilidade progressiva, percentagem de células com movimentos rápidos (Computer Assisted Semen Analisys -CASA), morfologia e viabilidade espermática em touros da raça Nelore criados na região sudeste do Brasil, considerando que esse resultado pode ser diferente em outras regiões do país, onde as temperaturas ambientais são mais elevadas.Palavras-chave: Sêmen. Sombreamento artificial. Nelore. Touro.

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“…A decrease in TC is commonly found in connection with acute or sub-acute testicular pathologies, such as testicular degeneration. Attempts to establish a relation between TC and seminal or fertility parameters of Bos indicus bulls have been inconclusive thus far [1,4], although morphological alterations of the seminiferous epithelium were more frequent in Zebu breeding bulls with low TC than in control bulls [5] and were often associated with temperature-induced testicular pathologies [6]. For Bos indicus, Bos taurus and crossbred breeding bulls extensively reared in Costa Rica, a negative relationship was found between decreased B mating.…”

mentioning

confidence: 99%

Morphological Features of the Seminiferous and Cauda Epididymides Epithelia of Breeding Zebu Bulls with Normal and Decreased Testicular Consistency.

Chacón

Müler

Íuez-Martínez

1999

Journal of Reproduction and Development

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Abstract. The fine morphology of the testes and epididymes collected from breeding Zebu (Bos indicus) bulls with normal or decreased testicular consistency (TC) at clinical palpation was studied. The ultrastructure of testicles with a slight to moderate reduction in consistency showed more obvious, albeit slight, degenerative changes in the seminiferous epithelium, with cellular debris present in Sertoli cells, compared with control animals. Abnormalities in the condensation of the chromatin and acrosomes during spermiogenesis were also common findings in cases of decreased TC. The cauda epididymides of these bulls did not show clear morphological deviations compared with controls, although the macrophagic activity of the epithelium was more pronounced, and cell debris as well as foreign cells were apparent in the lumen. The morphological findings confirm the relationship between a decreased TC at clinical palpation and the lowered normality of the testicular parenchyma, thus supporting the value of palpating scrotal contents as part of the field andrological clinical evaluation of breeding Zebu bulls in the tropics. Key words: Testicular consistency, Bos indicus, Ultrastructure, Testis, Epididymis.(J. Reprod. Dev. 45: [119][120][121][122][123][124][125][126][127][128] 1999) eef production in the tropics is based mainly on extensive production systems and natural ity [3] in European breeds under temperate conditions. A decrease in TC is commonly found in connection with acute or sub-acute testicular pathologies, such as testicular degeneration. Attempts to establish a relation between TC and seminal or fertility parameters of Bos indicus bulls have been inconclusive thus far [1,4], although morphological alterations of the seminiferous epithelium were more frequent in Zebu breeding bulls with low TC than in control bulls [5] and were often associated with temperature-induced testicular pathologies [6]. For Bos indicus, Bos taurus and crossbred breeding bulls extensively reared in Costa Rica, a negative relationship was found between decreased B mating. Under these conditions, it is essential that a complete clinical examination of the breeding bulls be made [1] and that clinical parameters related to the fertility of the bull be used as selection criteria for breeding purposes. One of these clinical parameters is testicular consistency (TC), which is normally evaluated while palpating the scrotal contents. Testicular consistency has been shown to be related to conception rate [2] and semen qual-

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Heat stress and spermatogenesis in Bos indicus and Bos taurus cattle

Cited by 111 publications

References 0 publications

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Efeitos da disponibilidade de sombra a campo sobre características reprodutivas de touros da raça Nelore (Bos indicus) criados na região Sudeste do Brasil

Morphological Features of the Seminiferous and Cauda Epididymides Epithelia of Breeding Zebu Bulls with Normal and Decreased Testicular Consistency.

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