01912naa a2200253 a 450000100080000000500110000800800410001910000190006024501400007926000090021952011690022865000280139765000110142565000210143665000270145765000100148465000150149465000190150965000170152865000100154565000160155565300230157177300640159415303082023-08-28       1997    bl uuuu     u00u1 u    #d1 aWINDSOR, D. P.  aVariation between ejaculates in the fertility of frozen ram semen used for cervical insemination of Merino ewes.h[electronic resource]  c1997  aTwo field experiments were conducted to investigate the amount of variation between rams, and between ejaculates within rams, in the fertility of frozen--thawed semen used for cervical insemination. Individual ejaculates from seven Merino rams were frozen and used to cervically inserninate Merino ewes at a synchronized oestrus at two sites. ln Experiment 1 (N = 491). pregnancy rates (deterrnined 70-80days after insernination) for individual rams ranged from 1.8 to 11,9%. Individual ejaculates produced pregnancy rates between 0 and 21.4%. Overall conception rate was 6.5%. No significant differences were detected. Pregnancy rates for the same rarns in Experiment 2 (N = 449) varied from 10.3 to 32.6% (P &lt 0.05). Ejaculate pregnancy rates ranged between 0 and 60% (P &lt 0.01). Fertility of individual ejaculates within rarns differed for three of the seven rams used (P &lt 0.01). It is concluded that considerable variation in fertility of frozen rarn semen exists between ejaculates within rarns as weIl as between rarns. Possible sources (biological and arising from freezing artefacts) of such variation and their practical implications are discussed.  aArtificial insemination  aCervix  aCryopreservation  aEstrus synchronization  aMales  aPhysiology  aPregnancy rate  aReproduction  aSheep  aSpermatozoa  aSemen preservation  tAnimal Reproduction Sciencegv. 47, n. 112, p. 21-29, 1997.