Effect of different semen extenders and additives to insemination doses on ewe´s pregnancy ratets

Abstract

The aim of our study was to compare effects of two additives (glutathione or caffeine) to semen extenders (EquiPro or egg yolkbased diluent) on pregnancy rate of the cervically inseminated ewes. Semen was collected by an artificial vagina from 3 mature Lacaune and 1 Suffolck rams, pooled to eliminate individual differences and divided into five equal aliquots. The aliquots were diluted by either EquiPro or egg yolk-based extenders at 1:3 and supplemented with either glutathione or caffeine. The semen dose diluted in an egg yolk-based extender but without additives was served as a control. The pregnancy rate was significantly different (P<0.05) between the group of ewes inseminated with semen diluted in an EquiPro with glutathione (81.25%) and the group inseminated with semen diluted in a egg yolk-based extender added with caffeine (63.16%). No differences among the other groups have been observed, although glutathione, when added either to EquiPro (81.25%) or egg yolk-based (68.97%) diluent, showed a tendency to increase pregnancy rate when compared to caffeine. These results demonstrate that egg yolk-based extender can be substituted by a synthetic EquiPro extender for the insemination of ewes without reducing fertility. The addition of glutathione (but not caffeine) has a positive effect on fertilizing ability of ram spermatozoa.