Effect of select lipids and vitamin E on motility and viability of liquid and cryopreserved boar spermatozoa

Abstract

The objective of this work was to test the ability of membrane-incorporated lipid and antioxidant constituents to improve boar spermatozoa function, particularly after cryopreservation. In exp. 1, fresh boar spermatozoa (one ejaculate from each of five boars) was incubated at 37°C in Beltsville Thawing Solution (BTS) + select lipids with 0 (SL), 1 or 5% vitamin E (SL + E1% or E5%). The fluorescent indicator octadecyl rhodamine (R-18) was included to monitor fusion by flow cytometry. Spermatozoa fused more readily to SL or SL + E1% than SL + E5% (86%a vs. 89%a vs. 77%b, respectively; a, b differ, P < 0.005). In exp. 2, fresh boar spermatozoa (one ejaculate from each of four boars) was incubated with BTS buffer alone (control), or BTS with SL, SL + E1% or SL + E5%, omitting the R-18 dye, and held at 18 °C for 7 d. Overall, viability (measured with SYBR-14/PI) was higher in SL + E (59%a vs. 51%a vs. 69%b vs. 67%b for control, SL, SL + E1%, and SL + E5%, respectively; a, b differ, P < 0.035). Both SL and SL ± E1% increased the percentage of motile spermatozoa (total and progressive) after 3 h of storage (P < 0.05); all treatments had similar motility by 24 h, and 0% motility by 96 h. In exp. 3, boar spermatozoa (three ejaculates from each of three boars) was cryopreserved in BTS (control), SL or SL + E1% using a BF5 extender. Initially at 37° C, SL + E1% increased motility, while viability was similar for all treatments. Spermatozoa fused with SL + E1% had the most motile spermatozoa when cooled to 5°C during processing and after freezing and thawing (P < 0.05); the percentage of viable spermatozoa was similar among treatments. In conclusion, incorporation of SL + E1% into spermatozoa membranes improves motility and/or viability of preserved boar spermatozoa. Key words: Freezing, á tocopherol, swine, membranes