Plumping fluid added to storage medium increases twofold the functional life span of fowl spermatozoa in vitro at 4°C.

1. The objective of this study was to examine whether addition of plumping fluid (PF) to Lake's solution (LS) for storage of fowl spermatozoa in vitro at 4°C can prolong survival and improve the quality of spermatozoa. 2. In experiment 1, aliquots of spermatozoa were stored in vitro in LS alone and LS containing 10%, 25%, 50% and 75% (v:v) PF for 0.5, 24, 48, 72, 96 and 120 h at 4°C. After the end of each storage period, spermatozoa were evaluated for their viability, mobility and penetrability. Viability was determined using SYBR-14 and propidium iodide (PI) staining. Mobility was assessed using an Accudenz assay. Penetrability was assessed using spermatozoa-inner perivitelline layer (IPL) interaction assay. 3. In experiment 2, aliquots of spermatozoa were stored in vitro in LS alone and LS containing 25% and 50% (v:v) PF for 0.5, 24, 48 and 72 h at 4°C, and then fertility of the spermatozoa was evaluated using intravaginal artificial insemination (AI) in hens. 4. Storage of spermatozoa in LS alone resulted in loss of viability, mobility, penetrability and fertility within 48 h. In contrast, no loss of viability and penetrability was observed for the spermatozoa stored for 48, 96, 72 and 48 h in LS containing 10%, 25%, 50% and 75% (v:v) PF, respectively. In particular, fertilising capacity was not lost for the spermatozoa stored in the presence of 25% or 50% PF in LS for 48 and 24 h, respectively. 5. In conclusion, these findings demonstrated that in vitro exposure of fowl spermatozoa to PF during hypothermic storage in LS prolonged spermatozoa survival. A 25% (v:v) level of inclusion of PF in LS may be effective for the improvement of viability, penetrability and fertilising ability of the stored spermatozoa.