Relationship between In Vitro spermatological parameters and male fertility in holstein bulls

The aim of this study was to determine the fertility ability and spermatological parameters of frozen-thawed bull semen routinely used in artificial insemination applications in the field by analyzing them under laboratory conditions. Frozen-thawed ejaculates (straws) produced from 5 different imported Holstein bulls, each containing 5 different collection dates, were used in the study. Artificial insemination was performed with bull semens in a total of 175 head of cows, 35 from each bull, in Burdur / Yeşilova Center and villages. Bull semens used in artificial insemination was analyzed for motility, plasma membrane integrity (PMAI), viability, lipid peroxidation level and mitochondrial oxidative stress. Pregnancy status of the animals was evaluated by determining the ultrasound examination at 60 days after insemination. No significant correlations founded between in vitro spermatologic parameters and pregnancy rate (p>0.05). However, a positive correlation was detected between motile results and pregnancy rate results in one bull (p<0.05). While no statistical difference was detected between bulls in terms of motility, viability, and lipid peroxidation level (p>0.05), statistical differences were detected between bulls in terms of PMAI and mitochondrial oxidative stress parameters (p˂0.05). There was no statistical difference between bulls in terms of pregnancy rates (p>0.05). When spermatologic parameters were evaluated among themselves, positive correlations were found between motility with PMAI and viability; positive correlations were found between PMAI with viability and lipid peroxidation level; negative correlations were found between mitochondrial oxidative stress with viability and lipid peroxidation level; and positive correlations were found between viability and lipid peroxidation level (p˂0.05). As a result, it is seen that the organelles and structures that make up the cell maintain metabolic activities in close relation with each other. In addition to correlating single spermatological parameters, it is thought that more than one combination should be created for multiple regression analyses to predict and correlate fertility, associations and correlations should be made in bulls with high and low fertility, and studies should be carried out on how and through which pathways these relationships and differences between bulls are formed.