Effect of an extender enriched with algerian date palm pollen on chilled semen characteristics of rabbit bucks at different ages

In the present study, we evaluated the effect of various concentrations of date palm pollen (DPP) aqueous extract on rabbit sperm during storage at 4°C for 48 h. Semen was collected from old and young rabbit bucks using an artificial vagina and initially evaluated for sperm quality. The sperm were diluted in Tris buffer supplemented with (20, 40, 80 mg/mL) of DPP aqueous extract. The extended samples were stored at 4°C for 48 h. Sperm motility and motion kinetics were assessed after 2, 4, 24 and 48 h of storage. At each time, an aliquot was frozen for the analytical evaluation of thiobarbituric acid reactive substances (TBARS) (lipid peroxidation) and tocols (vitamin E). Proximate composition, antioxidant and sugar content were evaluated in DPP. The results showed that DPP was characterised by a high proportion of protein (27.10%) and ash (18.43%), whereas the lipid fraction was very low (0.51%) and total sugar was also high (16.25 g/100 g of fresh matter, f.m.). Regarding the antioxidants content, the sum of tocols showed a total value of 26.48 mg/g f.m. The total polyphenols content was 5.01 mg gallic acid equivalents/g f.m, and polyunsaturated fatty acids was around 30%. Date palm pollen extract had a dose-dependent effect on sperm parameters (curvilinear velocity [VCL] mainly) of old rabbit, although a null or negative effect was recorded at doses >DPP40. Conversely, in optimal conditions (i.e. young rabbit semen), the addition of pollen had no effect on sperm traits (motility and VCL). The progressive increase in DPP, despite providing sperm with an additional amount of tocols, also caused higher tocol consumption and an increase in lipid oxidation. In particular, DPP80 increased the TBARS level in sperm of both rabbit ages. The better trend was found in DPP20, where the tocol consumption figures were 10.46 % and 15.28 %, respectively, in old and young bucks, and the lipid oxidation was lower compared to the higher doses of DPP. In conclusion, the findings of this study demonstrated that supplementation of DPP extract to Tris buffer extender enhanced chilled rabbit semen traits only if administered in old rabbit semen at concentration lower than 40 mg/mL.