From the "Quantities" section of our Dictionary of Semenyms:

supply - the totality of semen that a man can ejaculate at one time; see quantity. “When my supply ran out and I stepped back, she stood shakily, still rubbing my body fluids into her smooth skin. She picked up a washcloth and wiped only the area around her eyes and nose; from her lips down, she still glistened aromatically.” —Michael K. Smith