PARSIPPANY -- On the heels of an undercover investigation by an animal rights group into a laboratory research company's practices, protesters picketed outside of the northern New Jersey offices of three pharmaceutical companies who do business with the company.

People for the Ethical Treatment of Animals (PETA) released a video and documents last week from its undercover investigation of the business practices of the Waverly, N.Y.-based company, Liberty Research.

PETA spokeswoman Alka Chandna said the investigation documented the "substandard conditions, improper experimental conditions, systemic neglect of the animals and incompetence" of Liberty Research.

"Liberty Research has been caught treating sensitive, trusting dogs and cats like pieces of disposable laboratory equipment," Chandna said. "PETA is calling on Merck, Zoetis, and Bayer to review our evidence and reconsider doing business with a company that has so little regard for dogs and cats."

Wednesday's protests outside of the headquarters of Bayer, Merck and Zoetis, Chandna said, were aimed at drawing attention to the business relationships these companies have with Liberty Research.

"We think that these companies need to take responsibility," Chanda said. "When companies use Liberty Research, frequently there are site visits. They're there. They're seeing the substandard conditions and yet they say nothing. We think there's complicity there."

Bayer and Zoetis, in separate statements, said animal testing played an important role in medical discovery but that these tests must meet certain standards.

Zoetis said it "adheres to high standards of animal care and welfare that meet or exceed those required by applicable laws and regulations, and we expect our research partners and suppliers to respect and maintain these high standards."

The statement continued: "Zoetis takes all reports of animal welfare concerns seriously, including public complaints such as the recent allegations about Liberty Research. When concerns are raised about our suppliers, as in this case, we investigate them and take appropriate steps to ensure compliance with our requirements."

Bayer, in its statement, said "all testing programs initiated on our behalf are conducted through partners that are monitored by external third party reviewers and are required to be re-registered annually."

It continued: "The extent to which we conduct our testing and re-registration is above and beyond what is currently required by law."

Messages placed with Merck and Liberty Research on Wednesday haven't yet been returned.

Justin Zaremba may be reached at jzaremba@njadvancemedia.com. Follow him on Twitter @JustinZarembaNJ. Find NJ.com on Facebook.