Intrauterine insemination in sows with reduced sperm number

Usually 2-3 x 10(9) sperm per insemination are used in pigs. In other species it has been shown that changing the site of insemination allows a reduction in the amount of sperm per insemination dose. The goal of this study was to determine the minimal number of sperm that can be used, without a reduction in either the pregnancy rate or the mean litter size, using surgical deep intrauterine insemination in sows after weaning. Three different sperm concentrations (5 x 10(8), 1 x 10(8) and 1 x 10(7) sperm cells extended in 0.5 mL Androhep) were inseminated into the tip of each uterine horn. In addition two groups of control sows were inseminated once intracervically 24-32 h after the first signs ofoestrus with 1 x 10(9) and 3 x 10(9) sperm in 80 mL Androhep extender. Animals that became pregnant were allowed to farrow normally. No significant differences were observed between groups inseminated surgically with the three different sperm dosages with respect to pregnancy or farrowing rate. There was also no significant difference between the results of these groups and the results obtained from the non-surgically inseminated control groups. Neither the mean number of live-born nor stillborn piglets was significantly different between the surgically inseminated groups and the control groups. The total number of piglets born in each group was also not statistically different. The data show that the sperm number to be used for surgical insemination can be lowered without loss of the fertilization potential and may be used in the field as soon as a suitable insemination device is available.