Semen was collected from four adult miniature Caspian horse with Missouri artificial vagina equipped with an in- line nylon filter to exclude gel.Houshang Nouri 1 , Armin Towhidi 1 , Raheleh Sadeghi 1
1. Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Abstract
The use of glycerol as a cryoprotectant for freezing stallion semen could be a factor involved in poor post-thaw motility and fertility rates.
In this study we evaluated combinations of two commercial semen extenders and three concentrations of Dimethyl-formamide to determine the combination that yielded the highest post-thaw sperm motility. A randomised 2 ×3 block design was used.
Semen was collected from four adult miniature Caspian horse with Missouri artificial vagina equipped with an in- line nylon filter to exclude gel from the semen sample housed in animal breeding center of Iran, Karaj(5 collections per stallion).
The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% Dimethyl-formamide (DMF) in standard commercial freezing extender.
Sperm motility was assessed by computer aided semen analyses (CASA) in fresh and post-thaw semen. There was a significant difference between the two extenders in the motility of spermatozoa after cryopreservation (43.76% for INRA 96; 32.70% for EZ Mixin OF;( p< 0.0001). Dimethyl-formamide at 4% in freezing medium yielded the highest postthaw motility, significantly better than 2% (P< 0.05).
Three of four stallions had significantly higher post-thaw motility using INRA 96 relative to EZ Mixin OF (P< 0.01), and two of four stallions had significantly higher post-thaw motility using 4% Dimethyl-formamide (P < 0.05).
The combination of INRA 96 and 4% Dimethyl-formamide in freezing medium gave the highest average post-thaw motility of 46.5%. In this study, INRA 96 combined with 4% Dimethyl-formamide yielded an average recovery of progressively motile sperm consistently above the 30% target.
Keywords: Miniature Caspian horse , cryopreservation , extender , Dimethyl formamide , semen