Evaluation of bacteriospermia after the cryopreservation process of boar semen samples= avaluació de la bacteriospèrmia després del procés de criopreservació de semen de porc

Abstract

Cryopreserved semen is very useful for artificitial inemination (AI) since it enables the semen to be stored for unlimited period of time ranging from months to years until it needs to be used. However, in the swine industry only 1% of the AIs are conducted with cryopreserved semen due to the low fertility rate of thawed semen samples. One of the factors that affect directly the quality and storage of sperm is, among others, bacterial contamination, referred as bacteriospermia. Bacteria can have detrimental effects upon the sperm cell causing, among others: sperm agglutination, damaged acrosomes, premature acrosome reaction and low motility and viability rates. Moreover, if the bacteria are pathogenic there is a risk of passing a disease to the sow. Bacteriospermia, is an issue that has been studied among mammals with fresh and cryopreserved semen. Nonetheless, with boar up to this date no articles have been found addressing bacterial contamination in cryopreserved (or frozen-thawed) semen samples. In this study an evaluation of bacteriospermia after sperm thawing. The semen samples belonged to four different boars and they had been cryopreserved in liquid nitrogen (LN2) for three years inside sealed plastic straws. Four straws, each from a boar were assessed for bacterial contamination. A total of sixteen colonies were isolated, which a total of thirteen out of sixteen (81.25%) could be identified by using the Polymerase chain reaction (PCR) and the BBL™ Crystal™ Enteric/Nonfermenter kit. The results showed that contamination occurred in all samples, being Gram-negative bacteria (68.75%) more prevalent. The contaminants isolated were Staphylococcus spp. (18.75%), Streptococcus spp. (12.5%), Burkholderia cepacia (25%), Yersinia pseudotuberculosis (6.25%), Yersinia enterocolitica (6.25%), Pasturella aerogenes (6.25%) and yeast (6.25%). Thus seems to show that bacteria present in semen samples are able to withstand the cryopreservation process. However, it cannot be determined which source of contamination might be, and it can only be hypothesised by literary review