The Trump administration is walking back its plans to sterilize wild horse populations in Oregon after receiving pushback from animal rights groups.

The Bureau of Land Management (BLM) late Wednesday night announced it would no longer be pursuing sterilization tests on a population of 200 horses in Oregon. Under the study, about 100 wild horses would be sterilized and studied as part of a test to explore population control options of the species.

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The remaining 100 horses would be used as a control group.

“Defendants intend to rescind the portion of the United States Bureau of Land Management Decision Record pertaining to the spay feasibility and on-range behavioral outcomes assessment study,” BLM lawyers wrote the judge Wednesday.

The decision to end the study follows an Oregon district court judge’s order last Friday to preliminarily block the testing that was slated to start this week.

Various animal rights groups, including the Animal Welfare Institute (AWI) and The Cloud Foundation, sued the Trump administration over its plans to test ovary removal procedures on wild mares, actions they urged were controversial and dangerous. The horses tested reside inside BLM’s Wild Horse Corral Facility in Hines, Ore.

In 2016 BLM backed down after the same groups sued the Obama administration over their plans to conduct the testing on horses in the Hines facility.

“We are gratified that the BLM has nixed these cruel experiments on federally protected horses, but it should not take two lawsuits over two years to convince a federal agency that America’s beloved wild horses deserve humane approaches to population management,” said Joanna Grossman, an equine program manager for AWI.

BLM said it does not comment on pending litigation.