ARTIFICIAL INSEMINATION IN FARM ANIMALS - Phenix-Vet

Artificial Insemination in Pigs 85and different algorithms are needed for each species. A previous version of the SQA namelythe SQA-IIC was consistent and suitable for the estimation of boar semen quality. There wasa good correlation between the sperm motility index (SMI) obtained by SQA-IIC and severalCASA parameters, especially with the percentage of motile sperm and with straight linevelocity (VSL). However, the SQA-IIC is based on an old technology meant for humansperm analysis and the SMI values are based on overall information of the quality of thesperm, and do not discriminate between concentration, morphology and motilityparameters. Recently, the SQA-Vp was introduced as an SQA device specifically designedfor boars in which the sperm movement can be visualized on a screen and motility is givenas percentage of motile sperm (López et al., 2011).In pigs, a motility score of 60% motile cells, independent of the method of assessment, isrequired to be considered as a fertile ejaculate (Donadeu, 2004). Above 60% motilespermatozoa, no differences in farrowing rate and litter size were recorded (Donadeu, 2004).Apart from morphology, several attempts were made to correlate motility with fertilityoutcome. When using adequate numbers of spermatozoa per insemination dose (3*10 9 ),correlation with fertility outcome was hard to establish (Gadea al., 2004). At lower semendose, motility was well-correlated with fertility parameters. In most studies involving pigs,the predictive effect of motility was evaluated using visual motility assessment. To increasethe discriminating power of the motility estimation, objective motility assessment by CASAmeasurements(Holt et al., 1997; Vyt et al., 2008) or motility of spermatozoa subjected to apercoll gradient (Popwell and Flowers, 2004) were used. These studies found motility to bepositively correlated with fertility, especially with litter size.3.3.4 Other sperm examination techniquesSperm examination techniques requiring specialized knowledge and expensive equipmentare not frequently used in commercial AI-centres. They are however used for research onporcine sperm. DNA fragmentation tests can be used to identify subfertile boars, but thestudy results are contradictory (Waberski et al., 2011; Boe Hansen et al., 2008). Somemetabolic responses of sperm like resistance to oxidative stress (López et al., 2010) and invitro fertilisation assays are also used for research purposes. The practical relevance of thesetechniques is limited due to the fact that most of the research on porcine semen is based onthe semen from good performing boars (López et al., 2010). Subfertile or nonfertile boars arerapidly culled because of economic considerations, and therefore, there is a lack ofinformation regarding sperm quality of infertile boars.4. Storage of liquid semenFrozen storage of boar semen still yields inferior fertility due to the loss of membraneintegrity during freezing and thawing. Consequently, freshly diluted semen (liquid semen)is widely used for AI on the day of collection or in the following days. For storage of liquidboar semen, two factors are very important: the temperature of collection and storage, andthe composition of the storage medium (Johnson et al., 2000).4.1 Temperature of collection, transport and storageA different composition of the phospholipids in the membrane of boar spermatozoacompared to bull spermatozoa, a low cholesterol/phospholipid ratio and an asymmetrical