Abstract
Aim: The present study was carried out to examine the relationships among frozen-thawed semen fertility, physical parameters, seminal quality, and testosterone concentration in Murrah buffalo bulls. Materials and Methods: A total of 30 breeding Murrah buffalo bulls (either progeny tested or under progeny testing program) were randomly selected from two government bull farms in Punjab. None of the bulls selected for this study had any preceding physical abnormality. A field fertility trial was conducted to determine the first service conception rate (FSCR). The number of females inseminated per bull semen was 10. All the bulls were inspected for structural soundness, measurement of scrotal circumference, testicular biometry, and internal pelvic area (IPA). Frozen-thawed semen was evaluated for total motility, progressive motility, viability, concentration, abnormality, and hypo-osmotic swelling test (HOST). Testosterone was estimated in blood plasma, seminal plasma as well as frozen-thawed semen extracts for establishing relationship. Results: The FSCR was 48% in the bulls having a scrotal circumference of ≥44 cm, although, there was no significant correlation between FSCR and scrotal circumference. Similarly, no consistent relationship existed between sperm concentration and scrotal circumference. A positive correlation was observed between IPA and FSCR (r=0.294). Of the six post-thaw seminal components (total motility, progressive motility, viability, HOST (%), total abnormality and concentration) only total motility had a high significant (p<0.01) correlation with FSCR (r=0.694). Varied correlations existed between other seminal parameters and fertility. Using a simple regression analysis, the post-thaw motility, IPA, prepuce length and testosterone (independent variables) combined to explain approximately 62% of the variation in the FSCR (dependent variable). Conclusion: The present study indicated that despite low to high correlations between seminal characteristics, physical parameters, fertility, and testosterone; the observations support the importance of these components and their function in maintaining semen quality and subsequent fertility.
Highlights
Artificial insemination (AI) has made possible the effective use of best breeding males, greatly improving the genetic quality of breeding herds [1]
The first service conception rate (FSCR) was 48% in the bulls having a scrotal circumference of ≥44 cm, there was no significant correlation between FSCR and scrotal circumference
A positive correlation was observed between internal pelvic area (IPA) and FSCR (r=0.294)
Summary
Artificial insemination (AI) has made possible the effective use of best breeding males, greatly improving the genetic quality of breeding herds [1]. The ability to consistently select the bulls with high semen freezability is essential to obtain viable pregnancies following AI. Differences in post-thaw semen fertility between bulls have been reported [2]. A number of semen manipulation techniques are available to improve freezability of spermatozoa [3]. The knowledge of basic biometric characteristics of the reproductive organs has been found to provide valuable information for the evaluation of breeding and fertility potential of the animals [4]. The determination of scrotal circumference is a good indicator of semen production
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