Single Layer Centrifugation with 20% or 30% Porcicoll separates the majority of spermatozoa from a sample without adversely affecting sperm quality.

Centrifugation of boar semen through one layer of 40% colloid (Porcicoll) was previously shown to separate spermatozoa from bacteria without having a detrimental effect on sperm quality. However, some spermatozoa were lost. The purpose of the present study was to determine whether 20% or 30% Porcicoll could be used to recover most of the spermatozoa without impacting on sperm quality. Insemination doses (n=10) from a commercial boar station were sent to the laboratory at the Swedish University of Agricultural Sciences and processed by Single Layer Centrifugation with 20% and 30% Porcicoll approximately 7 h after semen collection. The resulting sperm samples and controls were evaluated for sperm quality immediately and again after storage at 16-18 °C for 4 and 7 days. Sperm recovery was 94 ± 18% and 87 ± 15% for 20% and 30% Porcicoll, respectively (p>0.05). Sperm mitochondrial membrane potential and chromatin integrity were unaffected (p>0.05). The proportion of live spermatozoa producing superoxide (9±8%, 7±6% and 3±1%; p<0.05), and the proportion of spermatozoa with high stainability DNA (0.68±19%, 0.61±0.22% and 0.96±0.23%; p<0.05- <0.01), were marginally increased whereas membrane integrity, although high, was lower in the centrifuged samples than in the controls (82±8%, 83±5% vs.92±4%; p<0.05). In conclusion, centrifugation through 20% or 30% Porcicoll enables most spermatozoa to be recovered, without having a major effect on sperm quality. These results are encouraging for further studies involving microbiological investigation of the processed samples, and scaling-up to process larger volumes of boar ejaculates.