T.M. El-Sheikh

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ATTEMPET TO PRODUCE COLD RESISTANCE RABBITS

T.M. El-Sheikh, T.S.T. Seleem

Abstract
   The aim of this study was planned to evaluate the effect of cold exposure on diluted physical semen and pre mating does on fertility traits and tolerance offspring of NZW rabbit. A total of 420 mature NZW rabbits were used in this study. In vitro cold exposure to each of diluted physical semen, sperm enzymatic activities, during conservation to 37°C (control), 15; 10 or 5 °C (cold shock) to 30 minutes. Cold stress exposure of rabbit does were at 20°C (control), 15,10,5°C for 30 minutes pre-coitus. The obtained results revealed that, physical semen quality, spermatozoa storagability, decreased significantly (P≤0.01), while values of AST; ALT; ACP and ALP enzymes in diluted semen increased significantly (P≤ 0.01), due to temperatures of cold exposing at 15, 10 then 5°C, compared to control. Ovulation, kindling rates, litter size and weight at birth was highly significant (P≤ 0.01) and in descending order due to expose to cold stress pre artificial insemination for 30 minutes at 20, 15, 10 then 5 °C, respectively. Re-mated rabbit does which exposed to different levels of cold stress pre previous mating did not record any significant in fertility traits. Mortality rate of growing rabbits produced from semen or rabbit does exposed to cold stress were significantly (P≤ 0.01) lower discerningly as compared with other cold treatments. In conclusion, exposing rabbit semen and does to very severe cold stress (Shock) produced offspring have more tolerance and adaptation to cold stress.

Key words: Rabbits; cold stress; semen quality; fertility traits; natural mating; AI