Enhance ERCR classification scores of fertility in cryoconserved bull sperm using proteomic data

Introduction: The major problem of herd is represented by reproductive management and breeding of dairy cattle to obtain high production. This factors account for large parts on costs of food production. Otherwise is important to assess the fertility of a bull breeder. Estimated relative conception rate (ERCR) is a method of evaluating relative bull fertility (1). Several proteins have been described in stallion sperm but at the moment not in sperm bull with ERCR scores(2). Aim of this study is to evaluate, through differential proteome analysis, changes in protein expression profiles of spermatozoa from bulls with high fertility (high ERCR score) and low fertility (low ERCR score) in order to identify possible protein markers to be used as indices of fertility Methods: Bulls were classified with ERCR score and four groups were created (from very low to very high fertility) for proteomic analysis. Sperm proteins were separated by 2-DE and digitized maps from each class analyzed with image analysis (Progenesis SameSpot). Statistically different spots (Mann- Whitney p<0.05) were analyzed by MALDI-TOF/TOF. Results: lmage analysis high lighted three significantly up and down regulated proteins in ERCR groups Alpha-enolase was found to be strongly up-regulated in very high fertility (ERCR++; group. lsocitrate dehydrogenase subunit alpha( lDH-a) and triosephosphate omerase (TPl) showed highest expression in ERCR-/- group which is associated with a very low score of fertility. Conclusion: Present study provides the first evidence for protein variations linked to ERCR values in bull sperm proteome and results will be useful for the identification of biomarkers and evaluation the level of fertility. The present data have indicated several possible candidate protein biomarkers for high and low ERCR. Further investigations will be necessary to evaluate possible use of these markers in fast screening of bull semen (by flow cytometry).