Observations on fertility of ram semen frozen by different methods

Abstract

Ram semen deep frozen by three methods : in ampoules, synthetic straws, and pellet form, was used for insemination of 410 Merino ewes either once or twice in a single oestrous period. The diluent consisted of 83 mM glucose, 100 mM sodium citrate, 15 per cent (v/v) egg yolk, and the final dilution rate in samples frozen by all three methods was 1 : 2 containing 6 per cent (v/v) glycerol. The average lambing rate was 5.9 per cent. The lambing rates following insemination with ampoule, straw, and pelleted semen were 5.6, 4.4, and 8.9 per cent respectively, and did not differ significantly. Number of inseminations had no effect on fertility (5.6 per cent single, 6.3 per cent double insemination).