Quality of frozen semen of Brahman bulls used for routine artificial insemination in Bangladesh

Background: Semen must be of good quality to achieve satisfactory conception rate in any artificial insemination (AI) programme. The objectives of the present study were to evaluate the quality of frozen semen of Brahman bulls and compare the same semen derived from different sources. Methods: Fifteen frozen semen straws of Brahman bulls derived from 3 different sources (5 straws from each source) were evaluated with respect to volume, motility, concentration of spermatozoa and morphology of spermatozoa. Volume of semen was determined by micropipette, concentration was evaluated by haemocytometer technique, motility and progressive motility were evaluated by computer assisted sperm analyser (CASA), spermatozoa with normal acrosome, midpiece and tail were evaluated in formol-saline fixed semen and spermatozoa with normal head morphology were evaluated by Farley staining technique. Moreover, presence or absence of bacteria in semen was evaluated by Gram’s staining technique. Results: The overall semen volume, concentration, motile percentage, progressive motile percentage, percentage of spermatozoa with normal acrosome, midpiece and tail, and percentage of normal head morphology were 0.19±0.01 ml, 30.87±3.4x106/ml, 56.47±24.2 (%), 16.23±9.8 (%), 88.23±2.1 (%) and 95.1±1.6 (%), respectively. When compared, similar volume of semen (0.19 ml) was found in all frozen semen derived from different sources. The difference in percentage of motile spermatozoa between source B and C was significant (P<0.05). The difference in spermatozoa with normal acrosome, midpiece and tail in semen between source A and B was significant (P<0.05). The difference in the percentage of progressive motile spermatozoa, the concentration of spermatozoa and normal head morphology in semen among different sources of semen was not significant (P>0.05). The difference in percentage of motile spermatozoa, the percentage of progressive motile spermatozoa, the concentration of spermatozoa, normal acrosome, midpiece and tail, normal head morphology in semen between locally produced and foreign semen was not significant (P>0.05). All examined 15 semen samples were negative for presence of bacteria. Conclusions: Although the quality of frozen semen derived from Brahman bulls seems to be within normal limit, the post-AI conception rate should be determined to evaluate the fertilizing capacity of the used semen.