SIMPSON, Ill. — A pair of studies initially indicate that pyrethrum spraying and electro-ejaculation have little negative effect on bull behavior.

The research, being conducted at the University of Illinois’ Dixon Springs Agricultural Center, involves two dozen bulls. In one study, student interns sprayed the insecticide pyrethrum on the bulls when the animals were feeding.

The study began in 2012, when the bulls were sprayed daily and checked once weekly. The results have been encouraging, according to Frank Ireland, who heads up the cattle program at the center.

“Last year we didn’t see any effects from those products in bull fertility,” he said. “We saw no differences in sperm morphology. We saw no differences in sperm motility, and no differences in hormone levels, testosterone levels or scrotal circumferences.”

This year the bulls were again sprayed. In addition, researchers sprayed facilities housing the animals. A similar study done at Joplin, Mo., had indicated some detrimental effects.

“We wanted to see if adding those two methods of application would have any detrimental effects,” Ireland said. “We added a premise spray from Bayer Animal Health called Tempo. We sprayed the barns throughout the summer. We sprayed the bulls daily when we fed them with a hand sprayer. We collected blood samples, semen samples once weekly to see if it had any effect.

“We’ve done the motilities on all these bulls. We’ve not seen any detrimental effects again this year. We’re still analyzing hormone levels, the morphology of the sperm cells. All indications are that there are no detrimental effects.”

In a companion trial, researchers looked at behavior of bulls being subjected to an electro-ejaculator for a semen sample on a weekly basis. They looked for resistance from the bulls or changes in disposition.

The interns used a scoring system that included willingness to go through the chute system and how well the animals stood in the chutes during the process. They also measured vocal reactions, such as bellowing, along with exit speed leaving the chutes.

Ireland said he was pleasantly surprised with the results.

“I would have almost bet you that some of these 2,600-pound bulls coming through the chutes on a weekly basis would have gotten tired of it and said, ‘I’m bigger than you are, and I don’t want to come through the chute anymore,’” he said.

“But what we found out was that the bulls, if anything, got a little better. They either stayed the same or they got a little more acclimated to it. They were obviously not exhibiting any pain or they would have resisted coming through the chute week after week. Maybe they’re like dairy cows. They got used to the routine.”

Ireland and other staffers still are compiling results of the two studies.