76 the effect of glycerol concentrations in egg-yolk citrate extender on the quality of cryopreserved nguni bull semen.
Agricultural Research Council, Animal Production Institute, Germplasm Conservation and Reproductive Biotechnologies, Irene, Republic of South AfricaReproduction Fertility and Development (Impact Factor: 2.4). 12/2012; 25(1):185. DOI: 10.1071/RDv25n1Ab76
There are bull shortages in South African poor rural areas. Artificial-insemination technology could play a significant role on breeding emerging farmer's cattle. The objective of this study was to compare glycerol concentrations (0, 4, 8, or 12%) during freezing of Nguni bull semen to conduct AI in different villages. Semen was collected by electro ejaculator from 2 Nguni bulls of known and proven fertility. Collected semen samples were kept in a thermo flask (37°C) and transported to the laboratories within 10min after collections. Semen samples were pooled and evaluated by Sperm Class Analyser(®) and allocated randomly per treatment. Semen was then diluted (1:2 v:v) with egg-yolk citrate extender supplemented with either 0% (negative control), 4, 8, and 12% of glycerol concentration or AndroMed(®) (positive control). Semen samples were equilibrated for 4h at 5°C. After equilibration period, samples were loaded into 0.5-mL straws and placed horizontally into the controlled rate (-5, -8, -10, -12, -15, -25, -35°Cmin(-1)) from 5°C until target temperature of -80°C is reached. The frozen semen straws were stored in a liquid nitrogen tank (-196°C) until thawing. Treatment means were separated using Fisher's protected t-test least, and data are presented as mean ± SD. There was a significant differences (P<0.05) between raw total sperm motility (83.3±19.3) and frozen-thawed sperm with either 0% (0.0±0.0), 4% (30.2±13.4), 8% (47.9±12.5), or 12% (61.5±4.7) of glycerol and on AndroMed(®) (27.7±17.8) group. Regardless of the glycerol concentrations used, the freezing-thawing process reduced (P<0.05) the Nguni total sperm motility rate compared to uncryopreserved sperm (83.3±19.3). In conclusion, egg-yolk citrate extender supplemented with 12% glycerol yielded a better (P<0.05) total sperm motility rate (61.5±4.7) as compared with the 0% (0.0±0.0), 4% (30.2±13.4), 8% (47.9±12.5), and AndroMed(®) (27.7±17.8) group. Further studies are required to test other levels of glycerol concentrations (>12%) on freezing Nguni semen and conducting AI.
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