Viability of equine semen stored in a polyethylene system for transport for eight hours / Viabilidade do sêmen equino armazenado em sistema de polietileno para transporte por oito horas

ABSTRACT

Background: Equine semen storage and shipment, being it colled or frozen, allows the veterinarian to direct matings, providing the use of genetically superior stallions, which are mostly located in breeding stations or training centers. Achieving good pregnancy rates depends, beyond the moment of artificial insemination (AI), on factors related to the semen cooling, such as system used for transport, cooling rate, final storage temperature, storage time and individual variation among stallions, such as age and resistance to cooling. Based on these aspects, this experiment was conducted in order to test a polyethylene system to ship equine semen. Materials, Methods & Results: A total of 87 ejaculates from five stallions with known fertility were used. The stallions aged between 6 to 14 years old, being three Thoroughbred and two Miniature Pony horse. The ejaculates were collected twice a week using a Hannover artificial vagina. After each collection, the semen sample was macroscopically evaluated for appearance, color and smell. A semen sample was used to evaluate the parameters of total motility, vigor and concentration, being these last three parameters assessed by counting 100 sperm cells for analysis. These analysis were performed using an optical microscope, being the concentration taken with a Neubauer chamber after dilution of 120 (semen citrate formol). Subsequently to this, the semen was diluted 1+1 (diluent+semen) with skim UHT milk, and divided into four aliquots of equal volume, yielding a total of four groups. In the control group (GC) the semen was analyzed immediately after dilution (zero h - 0-h). Samples from other groups were stored for eight h (8-h) in three different devices Equitainer® (GE), BotuFLEX® (GB) or Polyethylene System - Cooled (SP) and non-Cooled (SPN). [...]