Viability and fertility of rabbit spermatozoa diluted in Tris-buffer extenders and stored at 15 degrees C

Artificial insemination (AI) in rabbits is not extensive in the breeding pr ograms of the rabbit meat industry. A limiting factor is related to the sem en preservation. In order to improve the use of AI, two experiments have be en conducted to evaluate sperm viability and fertility of rabbit semen chil led and stored at 15 degreesC after dilution in Tris-based extenders. In Ex periment I, pooled semen samples were diluted 1:10 (semen/extender) in four different Tris-based extenders (Tris-citric-glucose (TCG). TES-Tris-glucos e (TTG), Tris-citric-fructose (TCF) and TES-Tris-fructose (TTF)) and stored at 15 degreesC. Sperm viability was evaluated at 0, 24, 48, 72 and 96 h fo llowing dilution for total sperm motility (TSM), forward progressive motili ty (FPM), plasma membrane integrity (PMI) and acrosome integrity (NAR). Via bility of spermatozoa declined with time of storage (P < 0.05), irrespectiv e of the extender used. There were interactions between extender and time o f storage (P < 0.05) in all viability parameters evaluated. After 96 h of s torage, TCG provided the highest sperm viability (P < 0.05) and TTG the low est (P > 0.05). In Experiment 2., a field trial was conducted at a commerci al farm to evaluate the conception and farrowing rates of rabbit spermatozo a extended in TCG. After synchronization of oestrous and induction of ovula tion, 3713 does with different physiological conditions (nulliparous, primi parous, lactating and re-breeding) were inseminated one time (15 x 10(6) sp erm per doses) with semen stored at 0 (n: 1275), 24 (n: 1503) and 48 h (n: 935) at 15 degreesC. Overall conception and farrowing rates were 77.1 +/- 0 .7 and 70.4 +/- 0.7, respectively, and the mean litter size was 7.6 +/- 0.1 . Fertility results were unaffected by the time of semen storage (P > 0.05) . Regardless of time of semen storage, fertility results were affected by t he physiological conditions of does (P < 0.05). Nulliparous and lactating d oes showed the highest fertility and primiparous the lowest. In summary, th ese results indicate that Tris-buffer extenders are effective for preservin g viability and fertilizing capability of rabbit spermatozoa stored at 15<d egrees>C. (C) 2000 Elsevier Science B.V. All rights reserved.