**10. Freezing packages**

**8. The semen donors**

22 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

fertility of individual boars [55].

membrane [51].

**9. The composition of freezing extenders**

Variation between individuals in the extent to which their sperm are damaged by freezethawing has been reports in many species including pig [52-55]. For instance, some study assigned individual boars into good, average and poor freezability groups on the basis of their post-thaw sperm viability using a system of multivariate pattern analysis, and suggest‐ ed that cryosurvival of the sperm was not necessarily related to the observed quality of the semen sample. In addition to inter-animal variation, intra-animal variation such as differ‐ ence between ejaculate fractions has also been described as a source of difference in boar sperm freezability [56,57]. Some researcher found that sperm present in the first 10 ml of the sperm-rich fraction (portion I) better sustain cooling and freeze-thawing compared to those present in the rest of the ejaculate (portion II) [56]. These differences were manifested by motility patterns, the maintenance of membrane integrity and capacitation-like changes of sperm after thawing. However, variation between ejaculate fractions is dependent of indi‐ vidual boars, with some boars differing in the ability of the two ejaculate portions to sustain cryopreservation, while in other boars such differences were not detected [57]. The mecha‐ nisms underlying differences in cryosensitivity between different individuals and different ejaculate portions have yet to be elucidated, but there is some evidence for physiological dif‐ ferences between sperm from individual boars. Harrison and co-workers demonstrated that the stimulatory effects of bicarbonate on the process of capacitation differ among individual boars [58]. Also, the existence of differences in seminal plasma composition and sperm mor‐ phology has been hypothesized as a possible explanation for the distinct ability of different boars and different ejaculate portions to sustain cryopreservation [59,60]. In general, boar sperm heads present in portion I were significantly shorter and wider than those present in portion II, detected by using computer-assisted sperm head morphometry analysis (ASMA) [57]. It has been hypothesized that such differences could be genetic in origin. Thurston and co-workers using Amplified fragment length polymorphism (AFLP) technology to analyze genome of 22 Yorkshire (Y) boars indicated that 16 candidate genetic markers linked to genes controlling sperm freezability and these genomes varied among individual boars. Consequently, they may be useful for the prediction of both post-thaw semen quality and

A number of substances have been added to boar semen during cryopreservation in order to improve FT sperm quality. It has been investigated that egg yolk added to boar semen could protect sperm acrosomes during cold shock and hence reduce cryodamage of FT boar sperm [61]. Protection has been claimed to be due to both phospholipids and the low density lipo‐ protein fraction in egg yolk [62,63]. The mechanism of action is unclear but could be mediat‐ ed by either a less intense cellular dehydration or by stabilization of the sperm plasma Boar sperm have been frozen in many forms of packages. Pellet, a form of freezing bull se‐ men on dry ice, was adapted to freeze boar semen and first reported as in [47]. Boar sperm have also been frozen in 5-ml maxi-, 0.5-ml medium- and 0.25-ml mini-straws, as well as dif‐ ferent types of 5-ml flat plastic bags [67,75]. All package forms have their own advantages and drawbacks. The 5-ml maxi-straw contains one insemination dose but has a relatively small surface-to-volume ratio, which constrains optimal freezing and thawing throughout the sample. The plastic bags allow even more homogeneous freezing and thawing and also contain a whole insemination dose, but they are not suited for storage in standard liquid ni‐ trogen containers, and therefore are not in commercial use [71]. Pellets and the small straws (0.25- and 0.5-ml straws) have a cryobiologically suitable shape with a large surface-to-vol‐ ume ratio; thus theoretically, FT sperm in pellets and small straws are less damaged than those in maxi-straws [76,77]. However, with pellets, there are difficulty in the identification of the doses and a risk of cross-contamination during storage, and the thawing procedure is rather complicated as well [71]. Also, the small packages could contain relatively few sperm such as 250 to 500 x106 sperm per straw, which are not enough for a single dose of conven‐ tional AI in pigs. Eriksson and Rodriguez- Martinez developed a new flat plastic container (the FlatPack®) for freezing boar semen. This package could contain a complete insemination dose, allows a quick and uniform freezing and thawing due to its large surface-to-volume ratio, and fits into any conventional liquid nitrogen container. Nonetheless, insemination with large numbers of sperm, such as 5 to 6x109 sperm per dose, reduces the number of AI doses per ejaculate. Achieving successful AI with fewer sperm is more important if using boars of superior genetic merit [71].

**13. Transcervical deep AI**

spreading of AI with FT semen.

Intra-uterine insemination (IUI) (Figure 1a)

uterine horn [84,85].

rine insemination (DIUI)

Although few sperm are required for fertilization within the oviduct, this reduced number is the product of a sequential and very effective reduction along the process of sperm trans‐ port in the female reproductive tract (i.e., 25 to 40% of inseminated sperm are lost with the backflow and 50% of the rest of the sperm are ingested by leukocytes in the uterus; Matthijs et al., 2003). The problem to be overcome during AI is to get an adequate number of sperm to the uterotubal junction (UTJ) that could ensure the establishment of the functional sperm reservoir with enough viable, potentially-fertile sperm to ensure maximal fertilization. One strategy proposed to accomplish this is to decrease the number of sperm per AI-dose, by de‐ positing the semen directly in the uterus, and get sufficient sperm into the UTJ. Such deep AI with reduced sperm numbers is a relatively new reproductive practice that has attracted the attention of the swine industry. Such a method could also be advantageous for the

Improvement of Semen Quality by Feed Supplement and Semen Cryopreservation in Swine

http://dx.doi.org/10.5772/51737

25

There are basically two non-surgical procedures for depositing sperm into the pig ute‐ rus. These include semen deposition either in the uterine body [49,75,83] or into the

**Figure 1.** Sperm can be deposited in different procedures: (a) intra-uterine insemination (IUI) and (b) deep intra-ute‐

A non-traumatic transcervical catheter that allows an easy penetration of the cervix and dep‐ osition of semen in the uterine body of the sow has been designed. Briefly, a conventional catheter (outer catheter) is placed toward and locked into the cervix. An inner tube (around 4 mm outer diameter) is passed through the outer catheter, along the cervical lumen, to reach the uterine body or the posterior part of one of the uterine horns (about 200 mm be‐

**a b**

Fertility after transcervial deep AI of FT boar semen.
