Low density lipoproteins as cryoprotectants of rabbit semen cryopreservation

الملخص EN

The present study was carried out at the International livestock management training center, Sakha, Kfrelsheikh, belonging to Animal Production Research Institute, Agricultural Research Center, Ministry of Agriculture, Egypt; during the period from March to May 2013.

Aim of this study was to evaluate sperm characteristics and fertility of rabbit buck semen cryopreserved in tris-extender containing different levels of low density lipoproteins (LDL) as replacement of egg yolk.

Semen was collected twice weekly form twenty APRI rabbit bucks using artificial vagina.

Only ejaculates with ≥ 70% mass motility were used for dilution and processing.

Four extenders were used: Tris 20% egg yolk extender as a control, and substitution of whole egg yolk with 8, 10 and 12% LDL.

Semen was diluted and packaged into 0.25 ml straws, cooled, held at 5◦C for 4 h , and then frozen in liquid nitrogen and stored at -196◦C.

Percentages of progressive motility, livability, abnormality and intact acrosome were determined at postdilution, -equilibration, -thawing.

Results indicated that LDL extenders were more effective in preservation of rabbit sperm characteristics than whole egg yolk extender.

Percentages of progressive motility, livability, abnormality and intact acrosome were much higher (P<0.05) in the 10% LDL extender, being 49.5, 61.6, 10.4 and 71.3%versus 30.5, 38.2, 13.3 and 58.6% in the control extender in post-thawed semen, respectively.

Fertility rates were higher in extender containing 10% LDL compared with the control (75 vs.

60%).

In conclusion, an extender containing 10% LDL extracted from hen egg yolk could be used as a cryoprotective media because it improved the freezability and fertility of rabbit spermatozoa.