Charak Samhita
रसादीनां सङ्क्षयाच्च तथैवावृष्यसेवनात् । बलवीर्येन्द्रियाणां च क्रमेणैव परिक्षयात् ॥१७८॥
Generally, lesser semen is in elderly person due to deficiency of rasadi dhatu, consumption of avrishya (non-aphrodisiac) food, gradual loss of strength, energy and sensory-motor organs,
english translation
rasAdInAM saGkSayAcca tathaivAvRSyasevanAt । balavIryendriyANAM ca krameNaiva parikSayAt ॥178॥
hk transliteration by Sanscript