Significance of total sperm numbers and microscopic evaluation of bull semen frozen in pellets in relation to fertility

During 1978 semen of 12 bulls was frozen in pellets containing 10 million and 30 million total sperm cells respectively. N.R. (non return) rates of the pellets containing 30 million sperm cells were 3.44% higher (P<0.001). Differences among bulls however vary considerably.No significant differences could be proven when pellets made of semen qualified as “very good” were used in both concentrations. The qualification “very good” was made after an incubation test when the ejaculates showed at least 70% estimated motile spermatozoa.