18 SEMENRATE: THE USE OF COMPUTER-ASSISTED SEMEN ANALYSIS AND FLOW CYTOMETRY FOR OBJECTIVE BOVINE SEMEN ANALYSIS IN THE UNITED KINGDOM

Abstract

Routine assessment of bovine semen consists of a subjective assessment of morphology, motility and concentration. This subjective approach used during quality control at semen production centres (SPC) or investigations of poor reproductive performance in veterinary practice has been shown to be relatively inaccurate, imprecise, and operator dependent (Vincent, et al. 2012 Anim. Reprod. 9, 153–165). Assessment of frozen semen samples in a dedicated laboratory aimed to establish variations in multiple parameters associated with fertility using computer-assisted semen analysis and flow cytometry and evaluate their relationship to semen performance in the field. This has developed into a commercial service that is available to veterinarians and farmers across the United Kingdom. AI semen from 50 farms across Yorkshire, UK, that had been stored on farm was assessed for factors associated with fertility (motility, progressive motility, intact acrosome, viability, and polarised mitochondria). Data ranges and mean values for each parameter have been analysed. This analysis is ongoing as the dataset continues to expand and significance will be assessed. For frozen semen (n = 79), % viable sperm (max = 67.64, min = 0.00, mean = 43.44), % sperm with polarised mitochondria (max = 72.50, min = 0.26, mean = 38.56), % sperm with acrosome intact (max = 68.82, min = 0.06, mean = 35.29), % motile sperm (max = 66.90, min = 0.00, mean = 37.44) and % progressively motile sperm (max = 59.00, min = 0.00, mean = 26.11). 25% of the samples fell below the cut off for release of 30% motile sperm set by SPCs. For sexed AI semen (n = 9), % viable sperm (max = 66.31, min = 17.08, mean = 43.57), % polarised mitochondria (max = 26.74, min = 13.40, mean = 19.96), % intact acrosome (max = 52.62, min = 15.34, mean = 37.00), % motile (max = 38.00, min = 9.40, mean = 24.88) and % progressively motile (max = 22.80, min = 3.90, mean = 13.15). Objective semen analysis before beginning an embryo collection programme allows informed decisions to be made regarding semen choice and dosage depending on compensable v. non-compensable defects detected (Hudson et al. 2012 Dairy Herd Health 73–111; CABI Publishing). Use of semen that falls below the 30% cut off for SPCs is unlikely to perform as expected in the field (Phillips et al. 2004 Anim. Reprod. Sci. 80, 47–61). A European collaboration aims to establish correlations between semen quality parameters and fertility outcomes for UK cattle herds, providing unique data for the industry (Sellem et al. 2015 Theriogenology 84, 1447–1454.e5). These data should highlight to stakeholders in the industry how imperative optimal semen quality is and highlight the benefits to herd fertility and financial performance.