Sazonalidade Na Congelabilidade De Sêmen Bovino

Abstract

Eliane Vianna da Costa-e-Silva 1 QUEIROZ, V. L. D.; COSTA FILHO, L. C. C. da; ROSA, L. da S.; ZÚCCARI, C. E. S. N.; COSTA e SILVA, E. V. Sazonalidade na congelabilidade de sêmen bovino. Arq. Ciênc. Vet. Zool. UNIPAR, Umuarama, v.18, n.1, p. 39-47, jan./mar. 2015. RESUMO:O objetivo desta revisão foi apresentar e discutir os efeitos da sazonalidade nas características seminais de touros Bos taurus e Bos indicus antes e após o congelação, a fim de possibilitar maior rentabilidade econômica. Apesar da reprodução da espécie bovina não se caracterizar pela sazonalidade, estudos mostram a interferência das estações do ano na qualidade do sêmen de touros. O aumento da temperatura ambiente pode levar a elevação da temperatura testicular, das taxas metabó-licas e das exigências de oxigênio, ocasionando alterações na espermatogênese e, por consequência, a um impacto negativo na reprodução. Touros Bos indicus obtêm melhor desempenho na estação mais quente do ano apresentando uma qualidade de sêmen satisfatória em relação a touros Bos taurus. Isso se deve à maior resistência dos zebuínos às altas temperaturas e a peroxidação lipídica causada pelo calor resultando em menor produção de espécies reativas ao oxigênio e menor aumento nos defeitos nas células espermáticas. Desse modo, touros de origem europeia não apresentam um bom desempenho durante alguns períodos mais quentes do ano o que leva a questionar se a relação custo-benefício de aproveitamento do sêmen para criopreservação justifica o processamento do mesmo pelas Centrais de Coleta e Processamento de Sêmen nesta época. Esse fato tem levado algumas empresas a suspender atividades em determinados meses do ano. PALAVRAS CHAVE: Ambiente. Criopreservação. Espermatozoide. Estresseoxidativo. SEASONALITY IN THE FREEZABILITY OF BOVINE SEMENABSTRACT: The objective of this review was to present and discuss the effects of seasonality in the semen characteristics of Bos taurus and Bos indicus bulls before and after freezing in order to enable greater economic profitability. Even though the bovine reproduction is not characterized by seasonality, studies have shown the interference of the season on semen quality in bulls. The increase of temperature may lead to increase in testicular temperature, metabolic rates and oxygen requirements. Both thermal and oxidative stress will cause changes in the normal development of spermatogenesis, changing volume, sperm concentration, progressive motility, vigor and morphology of sperm cells, resulting in an economically negative impact on reproduction. Bos indicus bulls presented better performance in the hottest season of the year, showing a satisfactory quality of semen when compared to Bos taurus bulls. This is due to the greater resistance to high temperatures of zebu bulls and lipid peroxidation caused by the heat resulting in lower production of species reactive to oxygen and smaller increases in defects in sperm cells. Thus, European bulls, such as Bos Taurus, do not present a good performance in some of the hottest periods of the year, w...

Climatic adaptation of bovine subspecies monitored by seminal characteristics during winter months in tropical region

“…During the evolution of the bovine species, zebu animals developed better tolerance to tropical climates (Hansen, 2004;Queiroz et al, 2015 The ejaculate volume did not differ during the monitored months, nor did it present differences between the subspecies. Similarly, influences of temperature and seasons were not identified in the seminal volume from crossbred Jersey bulls, however, it was identified that the management of the animals and the intervals between semen collections generated differences in the ejaculate volume (Gopinathan, Sivaselvam, Kanniappan Karthickeyan, & Venkataramanan, 2018), factors that were minimized in the present study, since all the animals had the same management and the same semen collection routine.…”

“…In this context, it is essential to select breeding bulls capable of producing spermatozoa resistant to cryopreservation and maintaining high sperm viability and fertilizing capacity after thawing. However, not all bulls are considered suitable for frozen semen production, since there are innumerable intrinsic (age, bull's health, libido) and extrinsic variables (season, feeding, management) involved in this process (Queiroz, Filho, Rosa, Zúccari, & Costa e Silva, 2015;Ram et al, 2017).…”

Comparison of seminal characteristics of Aberdeen Angus, Holstein and Nelore bulls before and after cryopreservation

“…In order to obtain good results in the use of artificial insemination, rigorous quality processes are necessary, from the management of breeding bulls to the stages of collection and cryopreservation of the semen, taking into account that the process of the semen cryopreservation causes a drop in sperm quality (Abud et al, 2014;García-Álvarez et al, 2014). Furthermore, it is essential to select breeding bulls capable of producing cryopreservation-resistant ejaculates and maintaining high sperm viability and fertilizing capacity after thawing (Ntenka et al, 2016;Queiroz et al, 2015;Ram et al, 2017).…”

“…However, not all bulls are able to produce frozen semen, since numerous intrinsic variables (age, bull's health, libido) and extrinsic (season, diet, management) are involved in this process. (El-Harairy et al, 2011;Queiroz et al, 2015). Another important factor to be considered is the difference in semen quality between the bovine breeds and the respective aptitudes of the animals, which even lacking scientific studies, it is speculated that dairy bulls produce ejaculates with higher quality compared to beef bulls (Morrell et al, 2018).…”