Pretreatment of bovine sperm with dithiobutylamine (DTBA) significantly improves embryo development after ICSI

We assessed the effect of pretreating sperm with dithiobutylamine (DTBA) to improve embryo development by intracytoplasmic sperm injection (ICSI) in cows. Acridine Orange staining revealed that when applied at different concentrations (2.5, 5, and 10 mM) and exposure times (5 min, 20 min, 1 h, and 2 h), DTBA reduced disulfide bonds in spermatozoa with the highest efficacy at 5 mM for 5 min. DTBA enhanced the percentage of spermatozoa with free protamine thiol groups compared with untreated spermatozoa (control) (P < 0.05); however, this result did not differ from that of dithiothreitol (DTT) treatment. The percentage of live spermatozoa after DTBA treatment was identical to that in the control, but significantly higher than that after DTT treatment (P < 0.05). After ICSI, DTBA treatment tended to improve male pronuclear formation rate (P = 0.071) compared with non-treated sperm injection. Blastocyst formation rate was significantly improved by DTBA treatment compared with that in DTT, control, and sham injection groups (P < 0.05). Blastocyst quality in terms of cell numbers and ploidy was not different among these groups. In conclusion, DTBA increases the efficacy of blastocyst production by ICSI even if DTT treatment does not work.