Fertility of Progestagen-Treated Ewes in Relation to the Numbers and Concentration of Spermatozoa in the Inseminate

Eight hundred Merino ewes in which oestrus was synchronized with progestagen.impregnated sponges were incorporated into an experiment of parallelogram design (4 X 5; n = 40) in which four doses (numbers) of spermatozoa were inseminated in five concentrations (numbers/ml), which involved a range in volume of inseminate from 0·012 ml to 1 ·6 m!. The purpose was to determine the importance on fertility of the number of spermatozoa relative to the degree of dilution, i.e. their concentration and the consequent volume in which a given number was inseminated. All ewes were inseminated 48 hr after withdrawal of sponges.