Measurement of Oxidative Stress Index in Seminal Plasma Can Predict In Vivo Fertility of Liquid-Stored Porcine Artificial Insemination Semen Doses

Abstract

The study evaluated the relation between the oxidative stress index (OSI) in porcine seminal plasma (n = 76) with sperm resilience and in vivo fertility (farrowing rate and litter size of 3137 inseminated sows) of liquid-stored artificial insemination (AI) semen doses. The OSI was assessed as the ratio of advanced oxidation protein products to Trolox-equivalent antioxidant capacity, both measured using an automated analyzer. Sperm motility (computer-assisted sperm analyzer) and viability (flow cytometry) were evaluated in semen AI-doses at 0 and 72 h of storage at 17 °C. Sperm resilience was defined as the difference between storage intervals. Semen AI-doses were hierarchically clustered as having high, medium and low seminal OSI (p < 0.001) with those of low displaying higher resilience (p < 0.01). Boars were hierarchically clustered into two groups (p < 0.001) as having either positive or negative farrowing rate and litter size deviation; the negative one showing higher seminal OSI (p < 0.05). In sum, seminal OSI was negatively related to sperm motility and the in vivo fertility of liquid-stored boar semen AI-doses, with the receiver operating characteristic curve presenting seminal OSI as a good predictive biomarker of in vivo fertility of AI-boars (area under the curve: 0.815, p < 0.05).

Keywords: in vivo fertility; oxidative stress index; pig; seminal plasma; sperm quality.

Figure 1

Values of oxidative stress index (OSI) in seminal plasma samples (n = 58) from porcine entire ejaculates (n = 58; one per boar). The ejaculates were clustered according to their seminal OSI values (hierarchical clustering, p < 0.01) as having low (between 0.75 and 1.89; n = 16), medium (between 2.01 and 2.91; n = 22) or high (between 3.04 and 5.54; n = 20) OSI values. The line indicates the median, the whiskers extend to the 5th and 95th percentiles, and dots represent the seminal OSI values. **** p < 0.00001; *** p < 0.0001; ** p < 0.001.

Figure 2

Box-whisker plot showing the differences (sperm resilience) in the percentages of (A) total motile sperm; (B) progressive motile sperm; and (C) viable sperm with intact acrosome between both evaluation time-points (0 and 72 h of storage at 17 °C) of artificial insemination semen doses (n = 58) of boar ejaculates clustered into three groups (hierarchical clustering, p < 0.01) according to the oxidative stress index (OSI) of seminal plasma. Low seminal OSI ranged from 0.75 to 1.89 (16 semen doses), medium from 2.01 to 2.91; (22 semen doses) and high from 3.04 to 5.54 (20 semen doses). Boxes enclose the 25th and 75th percentiles, whiskers extend to the 5th and 95th percentiles and the line indicates the median. ** p < 0.001; ns: not significant.

Figure 3

Distribution by hierarchical cluster analysis (p < 0.001) of the 18 boars used in artificial insemination programs into two groups for having (A) negative (between −2.79 and −0.16; n = 8) or positive (between +0.94 and +4.54; n = 10) farrowing rate deviations; and (B) negative (between −0.43 and −0.05; n = 8) or positive (between +0.01 and +0.83; n = 10) litter size deviations. The line indicates the median, the whiskers extend to the 5th and 95th percentiles, and the dots represent the boars. **** p < 0.0001; *** p < 0.001.

Figure 4

Box-whisker plot showing oxidative stress index (OSI) values assessed in the seminal plasma of ejaculates collected from artificial insemination boars hierarchically (p < 0.001) grouped as showing (A) negative (ranging from −2.79 to −0.16; n = 8) or positive (ranging from +0.94 to +4.54; n = 10) farrowing rate deviations and (B) negative (ranging from −0.43 to −0.05; n = 8) or positive (ranging from +0.01 to +0.83; n = 10) litter size deviations. Boxes enclose the 25th and 75th percentiles, the line indicates the median and the whiskers extend to the 5th and 95th percentiles. * Indicates significant differences (p < 0.05) in seminal OSI values between groups.

Figure 5

Nonparametric receivers operating characteristic (ROC) curve showing the ability of oxidative stress index (OSI) assessed in seminal plasma to predict in vivo fertility index of boars whose semen, as liquid-stored semen doses (17 °C), was used for artificial insemination. AUC: area under the ROC curve.