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During the last decade, environmental toxicants have been considered a potential cause for declining sperm quality. Toxic metals are not easily degraded and may accumulate along the food chain, which may negatively impact the semen quality of animals. In this framework, we conducted a meta-analysis to determine whether exposure to Al, As, Cd, Cr, Co, Cu, Fe, Mg, Mn, Hg, Ni, and Pb affects sperm and andrological parameters of domestic ruminants. We extracted 217 independent comparisons from 39 published articles selected from PubMed, Web of Science, and Scopus. Our findings showed that metal exposure reduced sperm viability (d

This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20-min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00 hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (p > .05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males.

This study aimed to evaluate the correlation between testicular biometry and semen variables, as well as, to relate testicular variables to the probability of selecting Nellore bulls with desirable sperm morphology when conducting breeding soundness evaluations (BSE). A total of 2055 BSEs from 506 bulls comprised the dataset. Biometric variables evaluated were: scrotal circumference, testicular volume, width, length, ratio and eccentricity; and semen variables were sperm motility, major sperm defects, minor sperm defects and normal sperm. Data of testicular biometry were correlated with data for semen variables using the Pearson’s correlation assessment. Effects of testicular variables in selecting for sperm morphology of bulls in the BSE were evaluated by logistic regression. Scrotal circumference, testicular volume, length and width were positively correlated to sperm motility (0.18 to 0.19) and normal sperm (0.24 to 0.27) and negatively correlated with values for major defects (−0.24 to −0.27), but for testicular ratio and eccentricity there were coefficients near zero for all semen traits. Testicular ratio and eccentricity were not suitable for predicting the probability of selecting a bull based on semen variables using the BSE, but scrotal circumference, testicular volume, length and width were highly significant (P

This study aimed to assess characteristics of bovine cryopreserved sperm and evaluate its relation to field fertility in fixed-time artificial insemination (FTAI). Semen samples of 16 bulls were used to inseminate 811 Nellore cows, and four of these bulls were also used to inseminate 101 Nellore heifers. Samples of the same ejaculate used for FTAI from each bull were analysed in the laboratory after thawing. Sperm motility and vigour were subjectively assessed by light microscope, and integrity of the plasma and acrosome membranes, and H2 O2 production were evaluated by flow cytometer. Relation among sperm characteristics and pregnancy rate of cows and heifers were evaluated by univariate and multivariate logistic regression. Subjective sperm motility and vigour did not affect the probability of pregnancy in cows or heifers. In univariate analysis for pregnancy in cows, sperm traits related to acrosome injury positively affected probability of pregnancy mainly when associated with plasma membrane integrity; H2 O2 production seems to be less important than plasma membrane integrity in affecting probability of pregnancy. In multivariate analysis, sperm traits related to injured acrosome positively affected probability of cow and heifer pregnancies while intact acrosome was negatively related to cow pregnancy. Intact plasma membrane and high H2 O2 production were positively related to cow pregnancy but negatively related to heifer pregnancy. Results suggest that a capacitation-like status of the acrosome may benefit probability of pregnancy in cows.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Este trabalho foi realizado com o objetivo de comparar os efeitos de diferentes crioprotetores e aditivos na criopreservação do sêmen equino sobre a viabilidade espermática in vitro pós-descongelamento. Para tanto, foram designados dois experimentos (E). No E1 objetivou-se comparar o efeito do glicerol (GLIC) e da dimetilformamida (DMFA), associados ou não, sobre a viabilidade espermática in vitro pós-descongelamento, o que conferiu quatro grupos experimentais: glicerol a 5 % (GLIC), dimetilformamida a 5 % (DMFA), dimetilformamida a 3% associada ao glicerol a 2 % (DG) e o tratamento controle, composto pelo diluente comercial Botu-Crio® (BC). Já no E2 objetivou-se avaliar o efeito do congelamento de sêmen de garanhões em diluente contendo glicerol e/ou dimetilformamida, associados à antocianina (ATC) e/ou colesterol carreado por ciclodextrina (CCC). Para tanto, os ejaculados foram congelados em dez diferentes tratamentos, de acordo com as associações entre crioprotetores e aditivos. As amostras de ambos os experimentos foram avaliadas mediante teste de termo-resistência (TTR) e por meio de citometria de fluxo quanto à integridade de membrana plasmática e acrossomal, potencial mitocondrial, produção de peróxido de hidrogênio intracelular e peroxidação lipídica da membrana plasmática; a avaliação quanto à organização da bicamada lipídica só foi realizada no E1. Os melhores resultados obtidos no TTR do E1 foram referentes aos tratamentos DMFA e DG (p0,05). A maior proporção de células com integridade de membrana plasmática e acrossomal foi observada nos tratamentos DMFA e BC (p0,05). Em relação ao E2, não houveram interações entre crioprotetores e diluentes para maioria das características estudadas, sendo as comparações realizadas entre grupos de tratamentos. Entre os crioprotetores, o grupo DMFA apresentou os melhores resultados quanto à motilidade espermática durante o TTR, seguido do grupo DG (p0.05). The highest proportion of cells with plasma and acrosomal membrane integrity was observed in DMFA and BC treatments (p0.05). About E2 there were no interactions between cryoprotectants and diluents for most traits, with comparisons made between treatment groups. Among the cryoprotectants, DMFA group showed the best results on the TTR, followed by DG group (p