Stallion Semen Cooling Using Native Phosphocaseinate-based Extender and Sodium Caseinate Cholesterol-loaded Cyclodextrin-based Extender.

The research explores how stallion semen cooling varies when different extenders—BotuSemen Gold and INRA 96—are used. Comparisons were made on factors like sperm motility, sperm velocity, plasma membrane integrity, and successful embryo recovery. The results suggested that BotuSemen Gold may offer a suitable alternative to INRA 96 in semen cooling procedures.

Objective and Approach of the Research

• The overall aim of the research was to determine the effectiveness of two extenders—INRA 96 and BotuSemen Gold—in preserving stallion semen during cooling. The criteria used to measure effectiveness included sperm motility, sperm velocity, plasma membrane integrity, and embryo recovery rates.
• The study was structured in three experimental sections, each with distinctive procedures and evaluations at different time intervals.

Experiment 1: Collection, Assessment, and Cooling of Semen

• 45 ejaculates from nine mature stallions were collected and assessed, then divided equally and extended with INRA 96 or BotuSemen Gold to yield 50 million sperm/mL. The extended semen was stored in three cooling containers for 48 hours.
• Sperm motility parameters, plasma membrane integrity, and high mitochondrial membrane potential were then checked at 0, 24, and 48 hours after cooling. The result was that BotuSemen Gold showed superior total and progressive motility compared to INRA 96.

Experiment 2: Cushion-centrifugation of Extended Semen

• The semen was treated through cushion-centrifugation, with the top layer (supernatant) discarded and the concentrated semen below (pellets) remixed at 100 million sperm/mL with the respective extender.
• Semen was then cooled and stored likewise, and the same parameters were evaluated at the same time intervals. The outcome was that INRA 96 and BotuSemen Gold extenders had similar total and progressive motility, but BotuSemen Gold had superior sperm velocity parameters at all timepoints.

Experiment 3: Breeding and Embryo Flushing

• Twelve mares were bred with 48 hour-cooled semen from one stallion and then had embryo flushing carried out 8 days post-ovulation.
• The embryo recovery rate was found to be the same for both extenders (50%).
• The conclusion drawn from this study was that BotuSemen Gold is a viable alternative to INRA 96 in clinical practice, on the basis of its consistently superior sperm velocity characteristics and equally effective embryo recovery rate.