PDF《Plenary Article》

Plenary Article New Aspects of Boar Sperm Encapsulation M Faustini Department of Veterinary Sciences and Technologies for Food Safety, University of Milan, Milan, Italy Contents The study takes into account the main steps and techniques for boar semen encapsulation, to optimize the instrumental insemination interventions.

The use of cheap, biocompatible polymers as alginate can assure a regular, constant release of spermatozoa in the sow reproductive system, avoiding the double ? triple intervention of insemination and reducing the employ of disposable materials. The encapsulation ? microen- capsulation of semen can therefore be the starting point of new, innovative systems of pig reproduction management. Introduction In the last decades, the domestic swine reached high levels of proli?city and fertility deriving from the non- algebraic sum of several innovative aspects and tech- nologies reached during time. Arti?cial insemination techniques undoubtedly gave a boost to these features. In pig reproduction, some di?culties arise from a double front, e.g. the reproductive characteristics of sow and boar;

it is well known that the sow shows much variable oestrus and oestrus to ovulation time, also under seasonality (Belstra et al. 2004) and variably dilated ovulation time span: as a consequence, a single insemination intervention per heat rarely can yield acceptable performances. On the other side, boar semen has a number of characteristics that limit the e?ective- ness of the standard procedures of semen dilution and cooling. Boar spermatozoa show a weak resistance of membranes to cooling below 15°C because of phase transition, and the standard dilution procedures lead to the so-called '

dilution shock'

, because of the medium- induced dispersion of protective proteins and seminal plasma antioxidant molecules and?or because of the loss of intracellular molecules (Johnson et al. 2000). An innovative reproductive technology should move to- wards a better spermatozoa preservation and assure a long-lasting delivery of viable sperms. This could be a money-saving solution, because a single insemination intervention could limit the costs owing to disposable material and work. A cheap, feasible alternative proce- dure to the widely di?used 2C3 inseminations per heat in the sow is a single fecundation by encapsulated, controlled release semen. This technique is not new in the controlled release ?eld: brie?y, the sperm as a whole is reduced into droplets surrounded by a soft, smooth and degradable polymeric wall;

the capsules'

softness and diameter allow the ?ow along the common sponge catheters, avoiding the need to produce alternative insemination disposable material. Capsule membrane can limit the sperm damage, allowing the in?ow of nutrients, the out?ow of metabolites and blocking the immunocompetent molecules on the outer surface;

on the other side, a suitable polymer membrane must avoid uterine mucosa side e?ects, must adhere to uterine mucosa to prevent semen re?ux and erode in a tunable, predictable fashion with targeted spermatozoa release. The Encapsulation Process and the Results in Swine The ?rst attempts in encapsulating spermatozoa date back to

1985 when the Nebel'

s research group realized by a 3-step technique poly-l-lysine capsules containing bull spermatozoa (Nebel et al. 1985), and the results were satisfactory in terms of sperm motility and intact acrosomes. The application of such technique on boar sperm evidenced an acceptable normal acrosome per- centage, but only 7% of spermatozoa were motile after