Successful Low Dose Insemination of Flow Cytometrically Sorted Ram Spermatozoa in Sheep
Article first published online: 20 JUL 2007
Reproduction in Domestic Animals
How to Cite
De Graaf, S., Evans, G., Maxwell, W., Downing, J. and O'Brien, J. (2007), Successful Low Dose Insemination of Flow Cytometrically Sorted Ram Spermatozoa in Sheep. Reproduction in Domestic Animals. doi: 10.1111/j.1439-0531.2007.00837.x
- Article first published online: 20 JUL 2007
- Submitted: 06.09.2006
The fertility of ram spermatozoa that had undergone flow cytometric sorting (MoFlo® SX) and cryopreservation was assessed after low-dose insemination of synchronized Merino ewes. Oestrus was synchronized with progestagen-impregnated pessaries, PMSG and GnRH treatment. Ewes (n = 360) were inseminated with 1 × 106, 5 × 106 or 15 × 106 motile sorted frozen-thawed (S1, S5, or S15 respectively) or non-sorted frozen-thawed (C1, C5 or C15 respectively) spermatozoa from three rams. An additional group of ewes were inseminated with 50 × 106 motile non-sorted frozen-thawed spermatozoa (C50) to provide a commercial dose control. The percentage of ewes lambing after insemination was similar for C50 (24/38, 63.2%), C15 (37/54, 68.5%), S15 (38/57, 66.7%), S5 (37/56, 66.1%) and S1 (32/52, 61.5%) groups (p > 0.05), but lower for C5 (19/48, 39.6%) and C1 (19/55, 34.5%) treatments (p < 0.05). This study demonstrates sorted ram spermatozoa are equally fertile to non-sorted spermatozoa even when inseminated at 2% of the dose. Furthermore, at very low artificial insemination doses (1 or 5 million motile) the fertility of sorted ram spermatozoa is superior to non-sorted spermatozoa inseminated in equal numbers. These results have significance for the future commercialization of sex-preselection technology in sheep as a reduction in the minimum effective sperm number will allow a corresponding decrease in the associated cost per dose.