Many things

They have come to inspect your growing body many times and had conversations. Apparently there arent many animal genitals that will fit in your giantly gaped pussy. The donkey was barely a stretch. Viewers want to see you ruined. Theres a special niche in bestial porn.

They keep you full of aphrodisiacs to keep you docile while they prepare you for bigger animal slongs. They hype up the show and the day comes your hugely pregnant, ungainly form is ushered into a much larger breeding stand and your nethers slathered in musk again. You hear clops and feel a huge erection pushed into your gaping hole, hilted easily in one smooth move. You hear soothing whinnys as the show pony humps his cock into your cunt, stirring up your insides. After 30ish minutes, the pony cums, leaving frothing semen packed into you. He pulls out with help and trots away, leaving your destroyed oozing pussy on display.

On to bigger things you suppose. They bring in an actual bull. His cock was a lot like the ponys but as thick as two fists. There is a stud horse they bring to fuck you. Your not sure they can bring in anything bigger thats survivable.

Eventually you give birth to the triplets, laboring easily and quickly in the middle of the night light a barn animal. You are impregnated again within 3 days with quintuplets for a wealthy couple. They speak in front of you like you are a dumb animal, which you suppose you have become. All your life has become is eating, being fucked by bigger animals, breeding, and birthing. You dont speak, or see. You sit around with your legs spread, ass up, tits being milked like a cow, pregnant belly dragging the floor. If only dad could see you now.