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Aim:The present study compared the testicular cytology and histology between crossbred (Holstein–Friesian [HF] × Tharparkar) and purebred (HF and Tharparkar) bulls to find out differences if any.Materials and Methods:Four peripubertal bulls from each breed were utilized for the study. Through percutaneous needle aspiration biopsy, Sertoli and spermatogenic cells were extracted, and morphometry was studied. For histological studies, testicular tissues obtained through unilateral castration were utilized. Sertoli cells specific GATA4 antibody was used to study the population of Sertoli cells in the seminiferous tubule through immunofluorescence.Results:The testicular weight, volume, and scrotal circumference differed significantly among the breeds. The diameter and area of the seminiferous tubule was high in HF, followed by Karan Fries (KF), and Tharparkar bulls. However, the degree of compactness, based on qualitative evaluation, was high in Tharparkar followed by KF and HF bulls. The intensity of Leydig cells was higher in Tharparkar bulls followed by KF and HF. The proportion of Sertoli cells was higher (p<0.05) in HF and Tharparkar bulls compared to KF bulls.Conclusion:It may be concluded that variations exist in testicular components of the breeds studied and the proportion of Sertoli cells in relation to spermatogenic cells was significantly lower in crossbred bulls compared to purebred bulls.

Sub-fertility is one of the most common problems observed in crossbred males, but the etiology remains unknown in most of the cases. Although proteomic differences in the spermatozoa and seminal plasma between breeds have been investigated, the possible differences at the sperm precursor cells and supporting/nourishing cells have not been studied. The present study reports the differential proteomic profile of spermatogenic and Sertoli cells in crossbred and purebred bulls. Testis was removed by unilateral castration of 12 peri-pubertal bulls (10 months age), four each from crossbred (Holstein Friesian × Tharparkar), exotic purebred [Holstein Friesian (HF)] and indigenous purebred [Tharparkar (TP)] bulls. Spermatogenic and Sertoli cells were isolated and subjected to proteomic analysis. Protein extracts from the Sertoli and spermatogenic cells of each breed were analyzed with 2-dimensional difference gel electrophoresis (2D-DIGE) and analyzed with Decyder™ software. Compared to HF, 26 protein spots were over expressed and 14 protein spots were under expressed in spermatogenic cells of crossbred bulls. Similarly, 7 protein spots were over expressed and 15 protein spots were under expressed in the spermatogenic cells of TP bulls compared to that of crossbred bulls. Out of 12 selected protein spots identified through mass spectrometry, Phosphatidyl ethanolamine binding protein was found to be over expressed in the spermatogenic cells of crossbred bulls compared to TP bulls. The protein, gamma actin was found to be over expressed in the Sertoli cells of HF bulls, whereas Speedy Protein-A was found to be over expressed in Sertoli cells of crossbred bulls. It may be concluded that certain proteomic level differences exist in sperm precursor cells and nourishing cells between breeds, which might be associated with differences in the fertility among these breeds.

Present study analyzed the changes in peripheral blood testosterone concentrations and testicular cytogram in relation to age and semen quality in crossbred males. Three different age groups of crossbred males viz. bull calves (6 months, n = 5), young bulls (15 months, n = 5) and adult bulls (4 to 6 years, n = 8) were utilized for the study. Testicular fine needle aspiration cytology technique was used to quantify testicular cytology and their indices. Peripheral blood testosterone concentrations were measured using enzyme-linked immunosorbent assay method. Semen samples collected from adult bulls were microscopically evaluated for quality parameters. Mean peripheral blood testosterone concentrations in bull calves, young bulls and adult bulls were 2.28±0.09 ng/mL, 1.42±0.22 ng/mL and 5.66±1.08 ng/mL respectively, and that in adult bulls were significantly different (p<0.01) from young bulls and bull calves. There was no significant difference between the proportion of different testicular cells in bull calves and young bulls. Between young and adult bulls, significant differences (p<0.01) were observed in the proportion of spermatocytes, spermatozoa, and sperm: Sertoli cell ratio. The proportions of Sertoli cells showed a significant difference (p<0.01) between the three age groups. The number of primary spermatocytes had a positive correlation with peripheral blood testosterone concentrations in bull calves (r = 0.719, p<0.01). Number of Sertoli cells per 100 germ cells was negatively correlated with blood testosterone concentration in young bulls (r = −0.713, p<0.01). Among different semen parameters in adult bulls, ejaculate volume (r = 0.790, p<0.05) had positive relationship, and sperm motility had significant negative correlation (r = −0.711, p<0.05) with testosterone concentrations. The number of Sertoli cells and Sertoli cell index had a positive correlation with various semen quality parameters (p<0.001). Results of the present study conclude that number of Sertoli cells and Sertoli cell index are good indicators of semen quality, but peripheral blood testosterone concentrations may not have a direct relationship with various seminal attributes in crossbred bulls.

The present study was undertaken to identify the differences in sperm kinematics between buffalo bulls with different fertility ratings. Murrah buffalo bulls (n=9) that were routinely used for breeding purpose under progeny testing programme were utilized for the study. Bull fertility was determined based on in vivo fertility trials and the conception rates (CR) were adjusted for different non-genetic parameters. Based on the adjusted CR, bulls were classified into high, medium and low fertile group. Frozen semen samples of these bulls were obtained and sperm kinematic parameters were assessed using a computer assisted sperm analyzer. The kinematic parameters analyzed included the curvilinear velocity (VCL), the linear velocity (VSL), the average path velocity (VAP), the amplitude of lateral head displacement (ALH), the linearity (LIN), the straightness coefficient (STR) and the beat cross frequency (BCF). In high fertile bulls, the proportion of motile spermatozoa was higher (p<0.001) than the medium and low fertile bulls. The VAP and VCL of sperm motion were significantly higher (P<0.05) in high fertile bulls compared to either medium or low fertile bulls. The VSL was significantly lower in low fertile bulls (P<0.005) compared to either high or medium fertile bulls. Spermatozoa from high fertile bulls had significantly higher (P<0.05) BCF, STR, ALH and LIN compared to either medium or low fertile bulls. Buffalo bull fertility was significantly and positively correlated with sperm motility, VAP, VSL, VCL and ALH.