**2. Feed supplement to increase boar semen quality**

The semen quality depends on individual, breed, season, confinement and boar health. It was found that the dietary supplements of antioxidants, vitamins and/or minerals can in‐ crease libido and semen characteristics in boars. Additions of antioxidants in seminal plas‐ ma or semen extender play an important role on boar semen storability. Semen with a normal motility contains higher polyunsaturated fatty acids (PUFAs) in cell membrane has that that having a low motility [1]. Short life span spermatozoa usually presented in low an‐ tioxidant condition resulting from the high lipid peroxidation of sperm plasma membrane. Spermatozoa in low antioxidants of seminal plasma also show a lower sperm motility, via‐ bility and normal morphology than spermatozoa in normal seminal plasma (Table 1) [1,2]. The feed supplements were expected to improve the semen quality by increasing the num‐ ber of sperm per ejaculation, motility, viability and antioxidant in cell and seminal plasma. However, it depends on the initial performance of the boar influencing on successfully im‐ proving semen quality. Therefore, the key roles of feed supplement containing the rich of PUFAs, vitamins and minerals to improve the semen quality are increasing the antioxidant to reduce the plasma membrane damages from ROS and increase the amount of PUFAs in sperm plasma membrane that may increase the percentage of sperm motility and vitality.

enclosing the residual cytoplasm are enriched in polyunsaturated fatty acids such as DHA [17,18]. The combination of high polyunsaturated fatty acid content and high ROS produc‐ tion in these immature sperm has been shown to lead to increased lipid peroxidation and subsequent loss of sperm function [14,15]. ROS-mediated damage to human spermatozoa was characterized in the early 1980s [19-24] and has been shown by many authors to be an

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

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

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To a first approximation, the process of lipid peroxidation involves the initial abstraction of a hydrogen atom from the bis-allylic methylene groups of polyunsaturated fatty acids, mainly DHA, by molecular oxygen. This leads to molecular rearrangement to a conjugated diene and addition of oxygen, resulting in the production of lipid peroxide radical. This per‐ oxyradical can now abstract a new hydrogen atom from an adjacent DHA molecule leading to a chain reaction that ultimately results in lipid fragmentation and the production of malo‐ naldehyde and toxic shortchain alkanes (e.g., propane). These propagation reactions are mediated by oxygen radicals. DHA is the major polyunsaturated fatty acid in sperm from a number of mammalian species, including the human, accounting in this species for up to 30% of phospholipid-bound fatty acid and up to 73% of polyunsaturated fatty acids. At the same time, DHA is the main substrate of lipid peroxidation, accounting for 90% of the over‐

**Characteristics Normal motility Low motility** Sperm per ejaculate (×10 9) 88.6±41.7a 76.9±36.2a Sperm motility, % 82.6±5.2a 30.6±12.8b Sperm viability, % 86.7±5.8a 31.5±14.9b Normal morphology, % 96.2±1.9a 85.1±4.9b Normal plasma membrane, % 83.3±7.4a 15.7±7.5b Total antioxidant status in seminal plasma (ng/ml) 1.54±0.35 a 0.80±0.56 b

**Table 1.** Semen characteristics and antioxidant capacity in seminal plasma of boars having normal and low sperm

Lipid peroxidation has profound consequences in biological membranes. The generation of the polar lipid peroxides ultimately results in the disruption of the membrane hydrophobic packing, inactivation of glycolytic enzymes, damage of axonemal proteins (loss of motility), acrosomal membrane damage, and DNA alterations [29,30]. Oxidation of phospholipidbound DHA has been shown to be the major factor that determines the motile lifespan of sperm in vitro [6,31,32]. Three basic factors determine the overall rate of lipid peroxidation of sperm in vitro: oxygen concentration and temperature in the medium (OXIDANT), the presence of antioxidant defenses (ANTIOXIDANT), and the content of membrane-bound DHA (SUBSTRATE). Thus, the higher the temperature and the concentration of oxygen in

important factor in the pathogenesis of male infertility [14,25-27].

all rate of lipid peroxidation in human spermatozoa [23,28].

Rows with different superscripts (a,b) differ P≤0.05 [1-2]

motility (means ± SD)
