Does aging of turkey males affect the cryosurvival of spermatozoa?

It is well known that males aging had a negative impact on sperm quality and consequent fertility. This is relevant in turkey industry where males are raised for semen production when they are from 29 to 60 wk aged. Then, despite the dependence of this industry on artificial insemination, only fresh semen can be used because sperm cryopreservation still not lead to good fertility results. However, little is known about the aging effect on cryosurvival of turkey spermatozoa. This work aimed at evaluating the effect of turkey male’s age on the in vitro quality of semen post-thaw. 5 pools of semen (9-12 ejaculates/ pool) were collected from Hybrid Large White toms when males were 32, 44 and 56 wk old. An aliquot from each pool was taken for the analysis on fresh semen, the remaining was four-fold extended, cooled, added with 8% of dimethylacetamide as cryoprotectant and frozen by dropping 80 μL of semen directly in liquid nitrogen to form frozen pellets. The samples were quickly thawed at 75°C for few seconds. Sperm mobility (Accudenz swim-down test), viability (SyBr-PI staining) and osmotic-resistance (HOS-test) were examined on fresh and post-thawed spermatozoa. Results showed that in fresh semen a low sperm concentration, mobility and osmotic-resistance were found in semen collected from 56 wk old turkey compared to that collected from 32 wk old toms (P<0.05). The freezing/thawing process caused a significant reduction of semen quality at all ages (P<0.05), however post-thaw sperm viability was significantly higher (P<0.05) when males were 32 and 44 wk old compared to that of 56 wk old toms (34.92±2.97 and 42.31±4.24 vs 23.71±8.79, respectively) and osmotic resistance was higher (P<0.05) when males were 44 wk old (33.05±4.80) than 56 wk old (18.46±5.48). These results show that the age of turkey males influences not only the quality of fresh semen, but also the cryosurvival of spermatozoa.