Sperm subpopulations influence the pregnancy rates in cattle |
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| Authors: | Myrian Megumy Tsunokawa Hidalgo Ana Beatriz Marques de Almeida Fábio Lucas Zito de Moraes Rodrigo Yudi Palhaci Marubayashi Fabiana Ferreira de Souza Thales Ricardo Rigo Barreiros Maria Isabel Mello Martins |
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| Institution: | 1. Laboratório de Andrologia e Reprodução Animal Assistida (LARAA), Universidade Estadual de Londrina (UEL), Londrina, Brazil;2. Médico Veterinário Autônomo, Londrina, Brazil;3. Departamento de Pós-graduação em Agronomia, Universidade Estadual de Londrina (UEL), Londrina, Brazil;4. Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, Brazil;5. Laboratório de Biotecnologia da Reprodução Animal, Universidade Estadual do Norte do Paraná (UENP), Bandeirantes, Brazil |
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| Abstract: | This study aimed to study the characteristics and subpopulations of spermatozoa from bulls with low and high reproductive performance based on pregnancy rates. Based on historical records of pregnancy rate from four farms, 24 bulls were selected. Two groups were established, with low pregnancy rates (n = 12; LOW), including bulls that presented pregnancy rates <52.27% (33.33% to 51.81%); and a group with high pregnancy rates (n = 12; HIGH), with pregnancy rates >52.27% (52.27% to 69.64%), after fixed-time artificial insemination (FTAI). The thawed sperm straws were analysed to sperm kinetics, morphology, plasma membrane integrity and sperm subpopulations. The LOW group exhibited a higher proportion of static cells (p < .05). In contrast, the HIGH group showed greater percentages for membrane integrity and total and progressive motility, and cells with fast and medium velocity (p < .05). In the cluster procedures, four sperm subpopulations were established. The low-fertility bulls presented the highest percentage of subpopulation 2 (41.46%), characterized by slow and progressive spermatozoa. The high-fertility bulls exhibited the highest percentage of subpopulation 3 (37.17%), characterized by fast and nonlinear spermatozoa. Results from this study indicated that bulls with greater percentages of fast and nonlinear spermatozoa seem to have greater fertilization capacity and the subpopulations analysis can be considered a tool to identify ejaculates with high fertility. |
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| Keywords: | fertility bull semen CASA system FTAI |
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