Monkeys on a high colesterol diet have a greater chance of developing hardening of the arteries after vasectomies, according to a scientific paper presented yesterday at the 34th annual meeting of the American Fertility Society. One doctor described the paper as "a shocker."

"We are not saying stop vasectomies today," said Dr. Nancy Alexander, a scientist at the Oregon Regional Primate Research Center and a collaborator on the study. "These findings are very preliminary."

Alexander and Dr. Thomas Clarkson, chairman of the Department of Comparative Medicine at the Bowman Gray School of Medicine in North Carolina, studied 10 monkeys over a period of 16 months.

The laboratory animals were fed a diet twice as high in cholesterol as that of the normal North American man. The major source of cholesterol was butter, comprising 42 percent of the animal's caloric intake.

After six months, the monkeys were divided into two groups, five given vasectomies and five not.

Ten months later, autopsies on the animals showed considerably more atheroschelosis in the vasectomized monkeys. Affected were the abdominal aortas, carotid arteries, some segments of the coronary arteries and the cerebal arteries.

The researchers say that after vasectomies it is common for males to develop antibodies to their sperm, which no longer has a normal anatomical outlet. This process may ultimately cause a weakening of the interlining of the blood vessels which can be worsened by a diet high in cholesterol.

An estimated 12 million men in this country have had vasectomies in the past decade.

The study suggests that men genetically inclined to heart attacks or strokes either watch their diet or not have vasectomies or both.

But, said Alexander, "it is imppossible to confirm even that much with certainty until further studies are done."