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ContentsTwenty ejaculates from _ve dairy AI!bulls were used to compare\ in a split!sample experiment\ the fertility ð45 day! non!return!rate "NRR# from more than 03999 AI# and sperm viability post!thaw of semen diluted with an egg yolk! "Tri! ladyl þ # or soybean!based "Biociphos!Plus þ # commercial extender[ The in vitro evaluations were divided in two experi! ments[ Experiment 0 "n 19# included post!thaw evaluations of motility "subjective and computerized#\ membrane integrity "CalceinAM:EthD!0\ SYBR!03:PI\ and osmotic resistance testÔ RT#\ and capacitation status "CTC:EthD!0#[ Experiment 1 "n 09# included evaluations of the capacitation!"CTC:EthD! 0# and acrosome status "FITC!PSA:EthD!0# during incubation with:without a challenge with solubilized zona pellucida pro! teins "SZP#[ No signi_cant di}erence in the fertility "58[0 2 9[7 versus 58[1 2 9[7# results was found between the two extenders[ In experiment 0\ the computerized motility evaluations post! thaw "CASA# showed higher values for Biociphos!Plus þ pro! cessed semen for the velocity patterns and lateral sperm head displacement[ After 5 h at room temperature "19Ð11>C# all the CASA motility patterns were signi_cantly higher for Biociphos! Plus þ [ The proportion of spermatozoa with intact membranes assessed by CalceinAM was signi_cantly higher in Biociphos! Plus þ "p ³ 9[990# compared to Triladyl þ \ but such di}erence was not seen when using SYBR!03 or the ORT!assay[ When using the CTC:EthD!0 assay\ a lower proportion of acrosome reacted "AR# spermatozoa post!thaw "p ³ 9[90# was found in Biociphos!Plus þ processed semen\ as well as a tendency "p ³ 9[96# for a higher number of uncapacitated spermatozoa[ In experiment 1\ the proportion of uncapacitated spermatozoa was signi_cantly higher for Biociphos!Plus þ when semen was incubated "27>C and 4) CO 1 # without SZP at both 9 "p ³ 9[990# and 29 min "p ³ 9[94#[ Concomitantly\ Triladyl þ showed a higher percentage of capacitated spermatozoa at 9 "p ³ 9[90#\ 29 "p ³ 9[94# and 019 min "p ³ 9[94#[ A higher "p ³ 9[94# incidence of AR!spermatozoa was seen in Triladyl þ at the beginning of the incubation with SZP[ No signi_cant di}erence between extenders was detected for the acrosome status by the FITC!PSA!assay[ Incubation with SZP induced acrosome reaction of capacitated spermatozoa in both extenders\ which was detected by CTC and FITC!PSA assays[ In conclusion\ fertility was not a}ected by Biociphos!Plus þ when 04 × 09 5 of spermatozoa per AI dose were inseminated[ The _nding that higher frequencies of spermatozoa seemed more membrane stable post!thaw\ when frozen in Biociphos! Plus þ \ might indicate that this extender better protects the sperm viability compared with Triladyl þ [

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The predictability of semen quality of mature sires from measurements at an early age is not well established. The aim of the present study was to determine age-dependent changes in the quality of bull semen for artificial insemination (AI). Semen was collected and frozen from each of six Swedish Red and White (SRB) dairy AI bulls when they were 1 and 4 years old. Three batches were randomly selected from each bull and age group. From each batch, semen was analysed immediately after thawing [post-thaw (PT), control] as well as after washing/resuspension (W) and after a swim-up procedure (SU). The analyses comprised subjective and computerized (computer-aided sperm analysis, CASA) measurements of motility as well as sperm concentration, morphology and membrane integrity. When semen was analysed, PT, overall sperm motility (CASA), concentration of motile spermatozoa and membrane integrity improved when sires were older. After SU, there was a similar improvement in membrane integrity and concentration of motile spermatozoa, but linear motility decreased. No significant differences between ages were recorded after W-treatment. The above findings indicate that SU is not only superior to W-treatment in differentiating semen quality among bulls but also reveals age-dependent changes. Improved motility and membrane integrity suggest increased viability of spermatozoa at 4 years of age in the SRB sires examined here.

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