Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 1999
Publication Date: N/A
Interpretive Summary: The Beltsville Sperm Sexing Technology has been developed to the greatest extent possible for application to the livestock industry. Its application to cattle is well established and commercial use of the technology is within a year of being introduced. One of the limitations of sexed sperm for the swine industry is the number of sperm that can be sorted into X and dY populations in a reasonable time period. Currently that rate is 6 millio of each sex per hour. However, the standard insemination dose for the pig is three billion sperm. That is a an insurmountable number for the use of sexed sperm. Therefore, the development of low dose insemination techniques in the pig is high priority. These experiments establish that 10 million sperm is sufficient for pregnancy in the pig if the semen is deposited near the oviductal end of the uterine horn in volumes approximating 0.5 ml. Although these results were accomplished using surgical insemination, the information is helpful to establish the necessary number of sperm needed t obtain fertilization in vivo. Increased efforts will be required to be able to develop a non-surgical technique for low dose insemination in the pig.
Conventional insemination techniques in pigs require 2 to 3x109 sperm/dose. When using the latest high-speed sperm-sorting technology, one can still sort only about 5 to 6 million of each sex of sperm per hour. The objective of the present study was to find the minimal sperm concentration at a low- insemination volume in pigs without diminishing fertilization rate and litter size using surgical deep intra-uterine insemination (IUI). Semen from 3 boars was collected and diluted with Androhep. In trial 1, 109 prepuberal gilts were synchronized and surgically inseminated into the tip of each uterine horn 32 h or 38 h after hCG treatment or at the time of ovulation, respectively. Pregnant gilts were allowed to go to term. Pregnancy and farrowing rates 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 lnumber of piglets, number of piglets born alive, stillborn piglets, and mummified fetuses. In trial 2, 34 gilts were inseminated as described above 32 h after hCG. Additionally, 9 gilts were inseminated once nonsurgically with 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 stained with fluorescent dye (Hoechst 33342) to visualize nuclei. Recovery rates varied between 71.4% and 84.4%. Fertilization rate of the lowest sperm concentration differed significantly from all other groups. Cleavage rates at specific developmental stages did not differ. No major differences were found between insemination groups as long as the sperm dosage was at least 10 million sperm per gilt. The low volume was sufficient for successful deep intra-uterine insemination.