== Age when Spermatozoa First Appear in the Urine ==
== Age when Spermatozoa First Appear in the Urine ==
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* Most spermatozoa produced are lost in the urine during periods of sexual abstinence.
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* The presence of sperm in the urine indicates that spermatogenesis is occuring.
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* Frequent urine collection is difficult in large domestic species and requires special equipment, so this method of determining pubertal onset has limitations.
== Age when the Ejaculate Contains a Threshold Number of Spermatozoa ==
== Age when the Ejaculate Contains a Threshold Number of Spermatozoa ==