Low dose insemination in synchronized gilts

Conventional insemination techniques in pigs require 2 to 3x10(9) sperm/dos e. When using the latest high-speed sperm-sorting technology, one can still sort only about 5 to 6 million sperm of each sex per hour. The objective o f the present study was to find the minimal sperm concentration at a low-in semination volume in pigs without diminishing fertilization rate and litter size using surgical deep intra-uterine insemination (IUI). Semen from boar s was collected and diluted with Androhep to 5x10(8), 1x10(8), 1x10(7), 5x1 0(6), 1x10(6) or 1x10(6) sperm/0.5 mi. In trial 1, 10(9) prepuberal gilts w ere synchronized and surgically inseminated into the tip of each uterine ho rn 32 h or 38 h after hCG treatment or at the time of ovulation, respective ly. Pregnant gilts were allowed to go to term. Pregnancy and farrowing rate s did not differ significantly except at the lowest sperm concentration if inseminated 32 h or 38 h after hCG treatment (p<0.05). No differences were found among insemination groups for the total number of piglets, number of piglets born alive, stillborn piglets, and mummified fetuses. In trial 2, 3 4 gilts were inseminated as described above 32 h after hCG. Additionally, 9 gilts were inseminated once nonsurgically with 1x10(9) sperm as controls. Gilts were slaughtered 48 h after insemination, and embryos were recovered. Embryos were cultured in NCSU 23 (120 h), evaluated morphologically and st ained with fluorescent dye (Hoechst 33342) to visualize nuclei. Recovery ra tes varied between 71.4% and 84.4%. Fertilization rate of the lowest sperm concentration(1x10(6) sperm/horn) differed significantly (p<0.05) from all other groups. Cleavage rates at specific developmental stages did not diffe r. After 5 days of in vitro culture, embryos developed to morulae and blast ocysts. No differences were found for these stages. In conclusion, no major differences were found between insemination groups as long as the sperm do sage was at least 10 million sperm per gilt. The low volume was sufficient for successful deep intra-uterine insemination. Embryo development was comp arable to the controls. (C) 1999 by Elsevier Science Inc.