Thesis Title

Effect of Processing Method and Extender on Motility and Fertility of Chilled Stored Stallion Spermatozoa

Date of Graduation

Spring 2004


Master of Natural and Applied Science in Agriculture


College of Agriculture

Committee Chair

Gary Webb


An experiment was designed to determine if pregnancy rates could be increased with the use of differential processing methods and the addition of the antioxidant pyruvate to storage media. Semen was collected from a mature stallion on an every other day basis. At least one aliquot from each ejaculate was diluted in a commercially available 2.4% skim-milk, 5% glucose extender (SKMG) at a ratio of 3:1 (extender:semen). Additional aliquots were centrifuged at 400 x g for 10 minutes to remove the majority of seminal plasma. The sperm pellet was re-suspended with the same extender used in the other treatment and supplemented at a ratio of 2:1 with a Tyrode's media (TLP) which contained 20 mM lactate and 6 mM pyruvate. Following processing, aliquots were stored for 48 hours in an Equine Express® container. Motility was analyzed post-storage (CASA® system) and treatments were used to inseminate mares. Thirteen mares were assigned to an extender treatment and bred every 48 hours after a follicle of 30mm was visualized by trans-rectal ultrasonography. Mares were checked for pregnancy 14 days post-ovulation. After the exam all mares were infected with Lutalyse® and assigned to the alternative extender treatment on the resulting estrous cycle. No sigificant difference (P>0.05) in pregnancy rates between SKMG, TLP, and fresh were realized although total and progressive motilities of spermatozoa stored in TLP were significantly higher (P<0.05) than those measured in SKMG. Findings of this study indicate that the addition of the antioxidant pyruvate to storage media had a significant effect on motility but not fertility.


antioxidant, pregnancy rate, storage, stallion, pyruvate

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© Carlina L. Dekat