As the liquid finally reached your cock, it did in fact begin to change. It started to lengthen until it was fix, then seven, then almost ten inches long. Then it started to harden and thicken up until it felt like a bar of steel was hanging between your legs. Your head was so engorged, it looked ready to burst, but as the Cowtaur had promised, it never did.
The cycle began, and every day it was repeated no fewer than twenty times. First, the skin of your sac would begin to stretch, and as it did, your balls grew to fill the available space. Once your sack was swollen enough and you couldn't take any more, you climaxed and a whole hour would pass by as you cum flowed out in massive streams to the vats. Your sac would shrivel as it was emptied, and as soon as the last drop was wrung out of you, the process began again. You were milked around the clock, twenty-four hours a day, three-hundred sixty five days a year.
Sometimes, the Cowtaur stopped by and altered the equipment to torture or humiliate you for her amusement. For example, she would shut off the pump once your sack was full and make you beg her to turn it back on so you could cum. Or she took your cock and emptied it into a bucket, which she then dumped right on your naked body. Once the sticky semen dried, it hardened into a crusty layer and she would delight in scraping it off your skin while you winced and cried in pain. Once, she even took the nozzle and rigged it so you were forced to swallow your cum as it was released. The Cowtaur giggled as she watched you struggle to gulp down the semen so you wouldn't choke and then left you there for the rest of the day. By the time she unhooked you, your stomach had bloated out so much from the intake of semen that it made you look extremely pregnant.
The Cowtaur decided that she liked the way it looked, so after ten cycles had been completed, she made you drink your semen for the rest of the day to, as she put it, "maintain your figure". Over time, the added hormones from consuming so much cum resulted in your breasts bloating out until you had generous C-cup boobs to go with your pregnant belly. Your hips began to slim down and your waist expanded, and combined with your already-slender girlish face and hair, which had been allowed to grow out for months, gave you the appearance of a beautiful naked woman with a cock and balls.
The Cowtaur became much more interested, visiting daily instead of only once in a while. Eventually, she unhooked you from the machine one day.