Production and Evaluation of Frozen Semen of Sahiwal Bull Using Two Different Diluters and Protocols

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The experiment was designed to evaluate the effects of diluters and freezing protocols on frozen semen production of Sahiwal breeding bulls. Imported 100% Sahiwal breeding bulls were then reared in the American dairy limited (ADL). Semen samples are processed and frozen once a week in the ADL. Spermatozoa with various motility patterns were collected; these included post-thawing, progressive, fast, slow, circular, and local. Computer Assisted Semen Analyzer (CASA) was used to measure the straight-line velocity (VSL), curvilinear velocity (VCL) and linearity (LIN) parameters. Two diluters (tris egg-yolk and tris egg-yolk aqua) and freezing protocols (slow freezing and fast freezing) were used for frozen semen production of these bulls. The significantly highest (P<0.05) number of post-thawing total, progressive and progressive fast motility (78.42±1.88, 73.50±1.90 and 59.68±2.10%), VCL (115.31±3.82µm/s) and lowest slow, circular and local motility (13.44±1.40, 0.57±0.08 and 4.92±0.41%), LIN (0.39±0.01%) was found in diluter 1 and freezing protocol 2. On the other hand, highest number of circular motility (0.77±0.18%) and VSL (44.83±1.17µm/s) was found in diluter 1 and freezing protocol 1 whereas highest number of slow and local motility (18.84±1.23 and 7.46±0.57%) and LIN (0.61±0.20%) and lowest progressive fast motility (48.73±2.28%), VCL (98.90±3.42µm/s), VSL (39.76±1.33µm/s) was found in diluter 2 freezing protocol 2 and also lowest post-thawing and progressive motility (73.44±1.94 and 66.51±2.02%) was observed in diluter 2 freezing protocol 1. The study reveals that diluter 1(one step egg yolk based) and freezing protocol 1 (5 steps) and 2 (2 steps) seems to be an efficient method for frozen semen production.