Derrick looked over the various animals and kept going back to the still-erect bull. The animal looked even more handsome and powerful the more he looked at it, but he was worried about the size of the male. If the animals on the Island wouldn't hurt him, then the huge organ would not do him any harm. But what if she only meant that the animals would not bite or otherwise attack? Then again, the bull might not even be interested in a human boy after mounting the cow.
He was startled by a sniff and lick of his rump by the bull, who had plodded around him while he pondered. Derrick looked back and saw the enormous pointed shaft hanging low and hard, and squatted at first, the dropped to his hands and knees. The bull moved forward, literally covering him, chest and belly dragging over Derrick's back as the end of the bull's penis caught in his buttocks. The tip pressed in, then started to slide into Derrick anus.
The boy's eyes widened and he gasped as more of the long, hard rod pushed in. He felt so odd, yet so good. The bull shifted and thrust deeper, and Derrick felt weight on his back press harder. Shoving up with his arms, Derrick started to take the weight of the massive animal, and as even more of the shaft was driven in, the bull's forelegs came off the ground and gripped at Derrick's sides.
A rhythmic slapping indicated the huge male was fully inserted and thrusting into Derrick. But how? The animal's penis was as long as the boy... but as the animal mounting him bellowed., so did Derrick - and he realized he had become a cow. Maybe not fully yet, but as the bull built to climax Derrick's last humanity was being driven out. He should pull away, not let the male come inside him. Her. Derrick could feel her womb, the passage open and receptive. She needed to... but the mating was not only powerfully pleasurable, but seemed more and more the right thing to do.
Derrick was dimly aware that her mindset was changing, that being pregnant with a calf or heifer was not what she should want. But as the pressure from the bullcock came to climax, she could not pull away, could not deny the conception that both she and the bull instinctively desired. When the bull ejaculated, the thick semen shot into Derrick. One of the bull's sperm would find a receptive egg in less than an hour, and Derrick would have to remain a cow until she had birthed and weaned her offspring.