Functional sperm parameters and fertility of bull semen extended in biociphos-Plus (R) and Triladyl (R)

Twenty ejaculates from five dairy AI-bulls were used to compare, in a split -sample experiment, the fertility [56 daynon-return-rate (NRR) from more th an 14000 AI) and sperm viability post-thaw of semen diluted with an egg yol k- (Triladyl(R)) or soybean-based (Biociphos-Plus(R)) commercial extender. The in vitro evaluations were divided in two experiments. Experiment 1 (n = 20) included post-thaw evaluations of motility (subjective and computerize d), membrane integrity (CaIceinAM/EthD-1, SYBR-14/PI, and osmotic resistanc e test; ORT), and capacitation status (CTC/EthD-1). Experiment 2 (n = 10) i ncluded evaluations of the capacitation-(CTC/EthD-1) and acrosome status (F ITC-PSA/EthD-1) during incubation with/without a challenge with solubilized zona pellucida proteins (SZP). No significant difference in the fertility (69.1 +/- 0.8 versus 69.2 +/- 0.8) results was found between the two extend ers. In experiment i, the computerized motility evaluations postthaw (CASA) showed higher values for Biociphos-Plus(R) processed semen for the velocit y patterns and lateral sperm head displacement. After 6 h at room temperatu re (20-22 degrees C) all the CASA motility patterns were significantly high er for BiociphosPlus(R). The proportion of spermatozoa with intact membrane s assessed by CalceinAM was significantly higher in BiociphosPlus(R) (p < 0 .001) compared to Triladyl(R), but such difference was not seen when using SYBR-14 or the ORT-assay. When using the CTC/EthD-1 assay, a lower proporti on of acrosome reacted (AR) spermatozoa post-thaw (p < 0.01) was found in B iociphos-Plus(R) processed semen, as well as a tendency (p < 0.07) for a hi gher number of uncapacitated spermatozoa. In experiment 2, the proportion o f uncapacitated spermatozoa was significantly higher for Biociphos-Plus(R) when semen was incubated (38 degrees C and 5% CO2) without SZP at both 0 (p < 0.001) and 30 min (p < 0.05). Concomitantly, Triladyl(R) showed a higher percentage of capacitated spermatozoa at 0 (p < 0.01), 30 (p < 0.05) and 1 20 min (p < 0.05). A higher (p < 0.05) incidence of AR-spermatozoa was seen in Triladyl(R) at the beginning of the incubation with SZP. No significant difference between extenders was detected for the acrosome status by the F ITC-PSA-aassay. Incubation with SZP induced acrosome reaction of capacitate d spermatozoa in both extenders, which was detected by CTC and FITC-PSA ass ays. In conclusion, fertility was not affected by Biociphos-Plus(R) when 15 x 10(6) of spermatozoa per AI dose were inseminated. The finding that high er frequencies of spermatozoa seemed more membrane stable post-thaw, when f rozen in BiociphosPlus(R), might indicate that this extender better protect s the sperm viability compared with Triladyl(R).