Effect of initial freezing temperature on the semen characteristics of frozen-thawed ram spermatozoa in a semi-arid tropical environment |
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| Institution: | 1. Department of Animal Wealth Development, Faculty of Veterinary Medicine, Zagazig University, Sharkia, Egypt;2. Biological Applications Department, Radioisotopes Applications Division, NRC, Atomic Energy Authority, Cairo, Egypt;1. Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;2. Jiangsu Provincial Academy of Environmental Science, Nanjing 210036, Jiangsu, China;3. School of Public Health, Peking University, Beijing 100191, China;4. Department of Civil and Environmental Engineering, University of Nevada, Reno, NV 89523, USA;1. Bako Agricultural Research Center, P.O. Box 03, West Shoa, Ethiopia;2. International Centre for Agricultural Research in the Dry Areas, Addis Ababa, Ethiopia;3. International Livestock Research Institute, Animal Science for Sustainable Productivity Program, Addis Ababa, Ethiopia;4. Schools of Animal and Range Sciences, Haramaya University, Haramaya, Ethiopia;5. International Livestock Research Institute, Animal Science for Sustainable Productivity Program, Nairobi, Kenya;6. School of Animal and Range Sciences, College of Agriculture, Hawassa University, Ethiopia;1. Department of Animal Wealth Development, Faculty of Veterinary Medicine, Zagazig University, Sharkia, Egypt;2. Biological Applications Department, Radioisotopes Applications Division, NRC, Atomic Energy Authority, Inshas, Cairo, Egypt |
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| Abstract: | Ram spermatozoa are sensitive to extreme changes in temperature during the freeze-thaw process. The degree of damage depends on a combined effect of various factors including initial freezing temperature. The present study was conducted to observe the effect of initial freezing temperature on post-thawing motility of ram spermatozoa of native and crossbred rams maintained in a semi-arid tropical environment. Good quality semen obtained from native Malpura and crossbred Bharat Merino rams were pooled within breed and diluted at a rate of 1000 million spermatozoa per milliliter in TEST—yolk–glycerol extender. Diluted semen samples were loaded in 0.25 ml straws and cooled to ?25, ?75 or ?125 °C freezing temperature at the rate of ?25 °C/min under controlled conditions before plunging into liquid nitrogen for storage. The thawing of straws was performed at 50 °C in a water bath for 10 s and motility characteristics of the frozen-thawed spermatozoa were assessed by a computer-assisted spermatozoa analysis technique. Initial freezing temperature significantly affected the post-thawing motility of sperm in both the breeds. The post-thawing % motility and rapid motile spermatozoa were significantly higher at initial freezing temperature of ?125 °C and lower at ?25 or ?75 °C. The percentage medium motile sperm were similar at all three initial freezing temperatures. The percentage of slow motile and linearity of sperm varied (P<0.01) between the different freezing temperatures. The curvilinear velocity, average path velocity and straight line velocity of spermatozoa were higher (P<0.01) at ?125 °C than ?25 or ?75 °C. Although the lateral head displacement of spermatozoa did not vary significantly between the different initial freezing temperatures, the stroke frequency was significantly lower at ?25 °C than ?75 or ?125 °C. Except for % linearity, the average path velocity and straight line velocity, other spermatozoa characteristics were not significantly different between breeds. The interaction between freezing temperature and breed was significant only for the % motility and linearity of the spermatozoa. The study indicates that initial freezing temperature has a significant effect on spermatozoa motility and velocity following post-thawing. The best motile spermatozoa following thawing were achieved at ?125 °C freezing temperature. |
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