401. In vivo development of embryos derived from sex-sorted and non-sorted ram sperm

Abstract

The use of sex-sorted ram sperm results in pregnancy rates similar or superior to that of non-sorted sperm after laparoscopic insemination of synchronised ewes under defined conditions [1, 2]. To further assess the fertility of sex-sorted ram sperm, embryo production and development rates were examined after the insemination of superovulated ewes with either sex-sorted or non-sorted sperm. Merino ewes (n = 30) were synchronised in oestrus using progestagen sponges inserted for 14 days and hormonally stimulated with PMSG (600 IU) on sponge removal (SR), FSH (133 mg) at decreasing doses every 12 h for 4 days before insemination, and GnRH 24 h before insemination. Each ewe was inseminated in the uterus by laparoscopy 42–44 h after SR with 15 × 10⁶ motile X- or Y-chromosome bearing or non-sorted spermatozoa. On day 6 after insemination, antegrade flushing of both uterine horns was performed. Overall, the fertilisation rate was higher using X-chromosome bearing sperm (70%) compared with both Y-chromosome enriched (59%) and non-sorted treatments (64%). Embryo development was more advanced after the insemination of non-sorted sperm with more hatching (hg) and expanded blastocysts (exb) recovered per animal (hg: 3.37 ± 1.19; exb: 5.00 ± 1.68) compared with sorted groups (X hg: 1.71 ± 0.92; exb: 3.28 ± 1.80; Y hg: 1.67 ± 1.67; exb: 1.50 ± 1.02). Moreover, embryos were recovered at earlier developmental stages after insemination with Y- compared with X-chromosome bearing sperm. In conclusion, the use of sex-sorted sperm did not affect the efficiency of embryo production. However, the development of embryos derived from sex-sorted sperm was delayed compared with those from non-sorted sperm.

(1) de Graaf et al. 2007. Reproduction in Domestic Animals 42, 648–653

(2) Beilby et al. 2008. Theriogenology [IN PRESS]