It was ``an act of God'' that brought two love-struck bulls together with the cows next door, says a man accused of negligence for failing to keep them apart. The bulls were unexpectedly freed from their pen when a tree limb felled by a storm crushed the fence enclosing them. They headed for Maggie and Blackbird, two pure-bred cows awaiting artificial insemination by a $770,000, prize-winning Angus bull named Broadway. Since the bulls, aged 9 and 13 months, may have beaten Broadway's time with the cows, the cows' owners were advised to wait 60 to 90 days before artificial insemination, to make sure Broadway was the father. Though this was done, the owners are suing Kirk Hardin, caretaker of the bulls and cows, for $39,000, accusing him of negligence in not keeping the guys and gals apart. Lonnie Pembrook, owner of Pembrook Cattle Co. near Fairview, and Tom Young, a New Jersey businessman, each owned a half-interest in Blackbird. Pembrook owns Maggie. Hardin, a specialist in artificial insemination and embryo transfer techniques, contends the fence mishap, in the fall of 1986, was an ``act of God'' that could not have been prevented or foreseen. The trial began Monday before a Payne County jury, and testimony ended Tuesday. Closing arguments are scheduled Friday. After the artificial insemination took place, the embryos were frozen, according to testimony. Pembrook picked up the frozen embryos in October, but there was no testimony on whether the embryos had since been placed in host cows.