Abstract
BackgroundThere is speculation that beef bull semen quality is inferior to that of dairy bulls although few scientific studies are available in the literature. The aim of this study was to evaluate sperm quality in beef bull semen and to determine which parameters could be indicative of fertility after insemination. Sperm quality, assessed by computer assisted sperm motility analysis and flow cytometric evaluation of membrane integrity, levels of reactive oxygen species, mitochondrial membrane potential, acrosome status and DNA fragmentation index, was evaluated in beef and dairy bull semen.ResultsFor beef bulls, normal morphology (r = 0.62, P < 0.05) and WOBBLE (r = 0.57, P < 0.05) were significantly correlated with 56-day non-return rate, whereas sperm quality was not significantly correlated with the fertility index score for dairy bulls. Membrane integrity (46 ± 8.0% versus 40 ± 11%, P < 0.05), normal morphology (87 ± 6% versus 76 ± 8%; P < 0.05), and high respiratory activity (52 ± 13 versus 12 ± 4%; P < 0.001) were higher for dairy bulls than for beef bulls. The DNA fragmentation index was lower for dairy bull spermatozoa than beef (3.8 ± 1.1% versus 6.1 ± 2.9%; P < 0.01), whereas some sperm kinematics were higher. Multivariate analysis indicated that type of bull (beef versus dairy) had an impact on sperm quality.ConclusionsDifferent assays of sperm quality may be needed for appropriate analysis of beef and dairy bull semen. These finding could be important for cattle breeding stations when evaluating semen quality.
Highlights
There is speculation that beef bull semen quality is inferior to that of dairy bulls few scientific studies are available in the literature
Computer assisted semen analysis (CASA) kinematics Except for total motility, progressive motility and BCF, the sperm kinematics were significantly different for the two types of semen (Table 1)
There were significant differences between sperm motility patterns in semen from beef and dairy bulls; the semen was frozen in different extenders on the two commercial cattle stations, which could have affected the assessment of kinematics
Summary
There is speculation that beef bull semen quality is inferior to that of dairy bulls few scientific studies are available in the literature. The aim of this study was to evaluate sperm quality in beef bull semen and to determine which parameters could be indicative of fertility after insemination. Seasonal differences in fertility may occur and oestrus signs may not be as the market for beef bull semen for inseminating beef cows is generally stable, it is increasing in countries such as Brazil, where sales of beef semen have risen from approximately 3 million to nearly 12 million in less than 20 years [6]. The aim of the present study was to make a retrospective analysis of sperm quality in commercial doses of frozen beef bull semen and to identify some parameters of sperm quality that could be used as indicators of potential fertility. A further aim was to identify where potential differences in sperm quality occur between beef and dairy bull semen
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