High total antioxidant capacity of the porcine seminal plasma (SP-TAC) relates to sperm survival and fertility

Abstract

The study attempted to clarify the role of total antioxidant capacity of seminal plasma (SP-TAC) on boar sperm survival and fertility after artificial insemination (AI). SP-TAC differed (P < 0.001) among boars (n° = 15) and, to a lesser degree, among ejaculates within male (4 ejaculates/boar). SP-TAC also differed (P < 0.001) among ejaculate fractions (43 ejaculates and 3 fractions per ejaculate), of which the sperm-peak portion of the sperm rich ejaculate fraction (SRF) had the highest SP-TAC. SP-TAC was not correlated with sperm quality (motility and viability) or functionality (intracellular ROS generation and lipid peroxidation) of liquid AI-semen samples stored at 17 °C for 72 h (90 AI-samples), but the decline in sperm quality was larger (P < 0.05) in ejaculates with low, compared with high SP-TAC (hierarchically grouped). The SP-TAC differences among ejaculate portions agree with sperm cryosurvival rates (14 ejaculates from 7 boars), showing sperm from sperm-peak portion better (P < 0.01) post-thaw quality and functionality than those from the entire ejaculate (mainly post-SRF). Boars (n° = 18) with high SP-TAC (hierarchically grouped) had higher (P < 0.05) fertility outcomes (5,546 AI-sows) than those with low SP-TAC. Measurement of SP-TAC ought to be a discriminative tool to prognosis fertility in breeding boars.

Figure 1. Scatterplot showing the seminal plasma total antioxidant capacity (SP-TAC) of ejaculates collected from15 boars (four ejaculates per boar).

Circles show the SP-TAC value measured in each ejaculate and the lines show the mean for each boar.

Figure 2. Box-whisker plot showing variation in seminal plasma total antioxidant capacity (SP-TAC) of the three ejaculate portions: the first 10 mL of spermatozoa-rich fraction (SRF), the rest of SRF and the post-SRF of 43 ejaculates (1 per boar).

Boxes enclose the 25th and 75th percentiles; the line is the median; and the whiskers extend to the 5th and 95th percentiles. (a–c) indicate significant differences (P < 0.05) among the ejaculate portions.

Figure 3. Histograms showing sperm quality parameters measured of artificial insemination semen doses stored 72 h of storage at 15–17 °C and hierarchically grouped according to the seminal plasma total antioxidant capacity (SP-TAC) as low (from 0.03 to 0.45 mmol/L, n° = 21), moderate (from 0.47 to 0.67 mmol/L, n° = 40) and high (from 0.68 to 1.04 mmol/L, n° = 29).

Data are showed as measurements recorded at 24 h and 72 h of storage (absolute values, to the left of each chart) and as the difference in percentage between both storage times (relative values, to the right of each chart). (a,b) indicate significant differences (P < 0.05) among different SP-TAC groups.

Figure 4. Box-whisker plot showing variations in sperm quality parameters assessed at 30 (left) and 150 (right) min post-thawing in cryopreserved sperm samples of first 10 mL of sperm rich ejaculate fraction (10 ml-SRF), the rest of SRF or a reconstituted entire ejaculate of 14 ejaculates (2 per boar).

Boxes enclose the 25th and 75th percentiles; the line is the median; and the whiskers extend to the 5th and 95th percentiles. a,b indicate significant differences (P < 0.05) among the ejaculate portions within the same post-thaw incubation time and 1,2 indicate significant differences (P < 0.05) between post-thaw incubation times within the same ejaculate portion.

Figure 5. Box-whisker plot showing variations in sperm functionality parameters assessed at 30 (left) and 150 (right) min post-thawing in cryopreserved sperm samples of first 10 mL of sperm rich ejaculate fraction (P1), the rest of sperm rich ejaculate fraction (P2) or a reconstituted entire ejaculate (EE, mixing aliquots of the portions collected separately) of 14 ejaculates (2 per boar).

Boxes enclose the 25th and 75th percentiles; the line is the median; and the whiskers extend to the 5th and 95th percentiles. a,b indicate significant differences (P < 0.05) among the ejaculate portions within the same post-thaw incubation time and 1,2 indicate significant differences (P < 0.05) between post-thaw incubation times within the same ejaculate portion. FU: arbitrary fluorescence units.