Stallion semen cooling using native phosphocaseinate based extender and sodium caseinate cholesterol loaded cyclodextrin based extender
The objective of this study was to compare semen parameters and embryo recovery rates of cooled stallion semen extended with INRA96 or BotuSemen Gold. In experiment 1, 45 ejaculates from nine mature stallions were collected, assessed, and equally split between both extenders and then extended to 50 million sperm/mL. Then, the extended semen was stored in three, passive cooling containers (Equitainer, Equine Express II and BotuFlex) for 48h. In experiment 2, the same ejaculates used in experiment 1 were cushion-centrifuged, the supernatant was discarded, and the pellets were resuspended at 100 million sperm/mL with their respective extender. Semen was then cooled and stored as in experiment 1. In both experiments, sperm motility parameters, plasma membrane integrity and high mitochondrial membrane potential were assessed at 0, 24, and 48h post-cooling.. For experiment 3, 12 mares (n=24 cycles) were bred with 48h-cooled semen from one stallion. Semen was processed as described in experiment 1. Mares had embryo flushing performed by 8d post-ovulation. In experiment 1, BotuSemen Gold displayed superior total and progressive motility relative to INRA 96 (p<0.05). There were no significant differences between the type of containers in any experiment. In experiment 2, INRA 96 and BotuSemen Gold extenders had similar total and progressive motility, but BotuSemen Gold had superior sperm velocity parameters at all timepoints. Embryo recovery was identical for both extenders (50%). Finally, the results obtained herein suggest that BotuSemen Gold is a suitable alternative to be included in semen cooling tests against INRA 96 in clinical practice.
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