Mary ran out into the cool night air, stripping her nightgown off. The grass tickled her bare feet as she stood on the lawn between the house and the barn, wondering what the random change would transform her into? Her breasts heaved with her excited breaths while her rounded stomach gleamed in the moon's light. She caressed her pregnant human belly for hopefully the last time, knowing that she was giving her baby a better, more carefree life away from that cheating bastard.
As she calmed, opening herself up to the change, Mary felt her breasts begin to ache in a strange way. Pregnancy had brought a lot of new aches and pains, as well as normal human changes to her once lithe body, but this felt ...different. Her bra straps began to feel tight, so she quickly removed it as well as her panties, standing naked on the lawn beneath the moon. She gently cupped her breasts, feeling their weight and warmth and a new... sloshiness? Her breast milk hadn't come in yet, but she knew it was could happen months before your due date... She tugged on her nipples, surprised when twin jets squirted into the night! "Oh wow." she breathed, amazed once again at the evolution and capabilities of the female body. Repeating the action, she soon noticed that the milk gave off a sweet, sort-of earthy smell, and her nose twitched as she craned her neck down to get a better whiff. Were her nipples... longer? They were! Beneath her fingers she felt a tingling in her nipples, the teats stretching downward as if gravity was pulling on them until suddenly they separated! She had four nipples! They slid lower, settling below her original breasts to form what was now definitely identifiable as an udder resting on her chest above her pregnant stomach. It looked just like the udders on their neighbor's cows! With a jolt, Mary realized that she must be turning into a dairy cow!
As she continued to support her changed mammaries, she felt her arms being pushed lower, not from the further increased weight, but she realized that her udder was migrating downwards. Her chest was flattening as her long nipples and milk-filled bag slid over her swollen belly and came to rest just above her crotch. With it's new placement, she realized she would soon be nursing her baby from all-fours!
A cramping sensation in her hands grabbed her attention, and as she released her udder and raised them in front of her face, she saw that her middle fingers seemed wider, or maybe connected? and much too long... her palm seemed stretched and her thumb, pointer and pinky fingers were shrunken compared to the two center digits. Something black was encasing the tips of those fingers, forming into... Oh! She had cloven hooves in place of her hands! Muscles appeared to stabilize her much longer arms, and she reached out to lower her hooves to the ground, finding that they now matched her legs in length! She felt them dig into the soft, damp ground as another cramp gripped her feet, her toes following the same path of transformation until she was standing on four hooves, her spine parallel to the ground.
More muscle bulked up in her thighs and she realized she was growing, expanding in almost every direction to better match the proportions of a heifer. Something tickled above her buttocks, and Mary craned her neck to look over her shoulder. She could just see a ropey tail pushing out from the base of her spine, growing rapidly until it reached an appropriate length and a tuft of brown fur puffed out. White fur then raced back up her new tail, spreading outward from the base of her spine. Brown splotches appeared amongst the white fur that quickly covered her hips, flowing down her legs and over her distended belly. As it reached her shoulders and started down her forelegs, Mary felt her neck streeetching, muscle developing to support her lengthening spine. Fur followed, Mary's hair-tie falling to the ground as her human hair was replaced with a tuft of white hair on the boney crown of her head.
Her ears twitched, suddenly appearing in her peripheral vision as they grew, pushing outward from the sides of her head into two large, pointed appendages, surprisingly controllable. Her spinal column had shifted, reorienting to exit from the back of her skull, allowing her to look forward while standing on four legs. Fur tickled downward over her face and she felt her nose broaden, pushing outward with her mouth as her eyes shifted to the sides of her head. Her long, pointed tongue flicked out, feeling her wide, sensitive nose and enhancing the scent of the green grass growing beneath her hooves.
Her calf kicked gently inside her stomach, and Mary let out a soft snort of contentment, lowering her head to graze. Her human cares had melted away at the Yiffr app completed it's task.