Prof. Alemayehu LemmaKefelegn Seyoum2023-12-172023-12-172022http://etd.aau.edu.et/handle/123456789/1054Various factors are believed to influence the quality of semen in breeding bulls. Among them breed, bull selection and management, diseases and evaluation methods are believed to be the most important one. Poor semen evaluation, such as used in the conventional methods that do not address aspects of the complex spermatozoon structure and subsequent fertilization process implies the production of semen with low conception rate compromising success of artificial insemination. Reports confirm that the Ethiopian Livestock Development Institute (LDI) uses the conventional method and produces semen characterized by low conception rate. A multiparametric semen evaluation using advanced technology and functional tests that sets a higher standard for approval would improve the quality of semen. Accordingly, a computer based integrated semen analysis system, and acrosomal and plasma membrane integrity tests were applied on semen collected from 14 breeding bulls (Boran = 4, Boran* Holstein Frisian Crosses = 4 and Holstein Frisian = 6). Bulls were additionally investigated for incipient general and reproductive diseases. After the initial conventional assessment, semen was evaluated using advanced multiparametric method at fresh, chilled and frozen stages for various semen quality parameters. There were significant (P < 0.05) breed differences between Boran and Holstein Frisian breeds in scrotal circumference (33.20 Vs 38.40cm), testes volume (254.40 Vs 367.50cm3), testes weight (264.10 Vs 381.40g), semen volume (9.81 Vs 11.39ml), pH (6.31 Vs 6.58), spermatozoa head abnormality (5.02 Vs 3.42%), Hypo osmotic swelling reactivity (39.55 and 49.46%) and acrosome intact live spermatozoa (43.29 and 49.67%), respectively. Total sperm morphological abnormality (18.10%) were significantly (P < 0.05) higher in the Crosses. Motility was significantly higher (82.5%, P < 0.05) in fresh Boran semen while the same parameter was higher in chilled (70.2%) and frozen (42.9%) semen from HF bulls. All kinematic parameters (VCL, VAP, VSL, ALH, BCF, LIN, STR, and WOB) were significantly different (P<0.05) at all stages of semen production among the three breeds, being lower for Cross breed bulls. The ISAS method and the functional tests applied in this study invalidated some of the values of sperm parameters from the conventional method. Moreover, results of HOST, acrosome integrity and sperm morphological defects were associated with one or more of sperm motion characteristics which were not revealed if only conventional method was used. With minimum cut-off values (total motility=40% and progressive motility=15%) in frozen semen, nearly 56% of semen produced at LDI failed to fulfill the minimum approval requirements by ISAS. This was very apparent in semen of Cross bulls for both parameters (total motility 33.1 Vs 12.9% progressive motility) and to that of total motility (33.9%) in Boran semen. All bulls investigated were found to have no general and/or reproductive health problems that influenced the quality of semen. It is therefore plausible to assume that poor semen quality resulting from absence of a more rigorous evaluation method could be one of the factors contributing to the low conception rate at the field level. The significance of introducing advanced methods of semen evaluation is incontrovertible; however, this finding has to be complemented with more field studies and investigation of risk factors in the female individual to get a complete picture. As LDI is bearing a huge national responsibility in advancing the cross breeding program based on AI, it becomes invariably mandatory to start using state of the art methods of breeding soundness examination and semen evaluation.enAcrosomal integrityBoranconventional methodCrossesHolstein-FrisianHOSTISASsemen qualitysperm kinematicsThesis