Seminal Plasma Proteins as Potential Markers of Relative Fertility in Boars

Abstract

This study investigated whether specific proteins from distinct seminal plasma fractions of boars could be related to in vivo fertility. Nine boars with acceptable sperm motility and morphology for use in artificial insemination demonstrated major differences in total number born and pregnancy rate when low sperm doses (1.5 billion sperm) were used to breed a minimum of 50 gilts per boar. The 2 lowest-fertility and 2 highest-fertility boars were chosen for evaluation of specific seminal plasma proteins. On 4 occasions, semen was collected and separated into 3 fractions based on sperm concentration (Sperm-Peak, Sperm-Rich, and Sperm-Free), and the fractions were analyzed for total protein concentration and abundance of major seminal plasma glycoprotein (PSP-I), AWN-1, and osteopontin protein using Western blotting techniques. The concentrations of these seminal plasma proteins were lower in the Sperm-Peak fractions compared with the SpermFree fractions (P , .05). Seminal plasma from the pooled SpermRich fraction used for artificial insemination was also subjected to two-dimensional gel electrophoresis to investigate novel protein markers related to in vivo fertility. Total piglets born (r 5 20.76, P 5 .01) and sperm motility at day 7 (r 5 20.74, P 5 .037) were again negatively correlated with a 22-kDa protein identified by mass spectrometry as PSP-I. However, fertility index and farrowing rate tended to be positively correlated (P , .10) with a 25-kDa protein, identified as glutathione peroxidase (GPX5), an antioxidant enzyme that may protect sperm membranes from oxidative damage. These candidate proteins merit further investigation as markers of fertility in boars.

Will AI in pigs become more efficient?

“…This handling is now switching towards a growing interest to scrutinize SP-composition and evaluate its relevance for sperm functionality, even fertility. Recent findings support the complex composition of boar SP [50][51][52] and also demonstrate the relevance of some SP-components, such as Glutathione Peroxidase 5 [53] or Paraoxonase-I [54], for promoting sperm fertility of liquid stored semen IA-doses.…”

“…In contrast, other SP-components, such as the major proteins PSP-1 and AQN-3, could impair fertility of boar sperm [53,55]. This functional contrast between SP-components should be considered before using raw SP as sperm extender of post-thaw semen, action leading to inconsistent fertility results [56,57].…”

Electrophoretic profile of boar seminal proteins

“…The 55-kDa fertility-associated protein has been identified as osteopontin (Cancel et al 1999), and the 26-kDa fertility-associated protein has been identified as lipocalintype prostaglandin D synthase (Gerena et al 1998). Using the Western blotting technique, Novak et al (2010) identified porcine seminal proteins, namely AWN-1 with molecular weight of 14 kDa and osteopontin with molecular weight of 70 kDa (OPN-70), 12 kDa (OPN-12) and 9 kDa (OPN-9). In pig, the addition of osteopontin during in vitro fertilization reduced polyspermy rates (Hao et al 2006) and improved embryo development after fertilization.…”

Quality of boar spermatozoa from the sperm-peak portion of the ejaculate after simplified freezing in MiniFlatpacks compared to the remaining spermatozoa of the sperm-rich fraction

“…Inter-animal differences in their ability to sustain sperm cryopreservation had been associated to the SP-composition (Flowers, 2001;Novak et al, 2010), genetic factors (Thurston et al, 2002), or by the existence of distinct spermatozoa subpopulations in the ejaculate, in terms of their morphological characteristics (Thurston et al, 2001) or movement patterns (Cremades et al, 2005).…”