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May 17, 2021

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BLM to test fertility vaccine as way to manage wild horses

L.E. Basbok's 2017 Photos of The Year

Horses make their way about the Spring Mountains area near Cold Creek on Tuesday, Feb. 28, 2017.

The Bureau of Land Management in Nevada will move forward with plans to administer a single-dose contraceptive vaccine on 16 wild mares in the next few months in a study to determine whether the oocyte growth factor vaccine is reliable and long-lasting enough to be an effective fertility control method.  

The agency is partnering with the U.S. Department of Agriculture Animal and Plant Health Inspection Service’s National Wildlife Research Center to conduct the experiment. 

The single-dose contraceptive includes an oocyte growth factor, which officials say could halt fertility for multiple years. The BLM currently uses a fertility vaccine — porcine zona pellucida — which only lasts up to one year. 

The purpose of the experiment is to test whether this form of fertility control is an effective, humane way to contain wild horse population growth for the long term. Since the passage of the Wild Free-Roaming Horses and Burros Act in 1971, federal agencies like the BLM are required to control any overpopulation of excess animals. 

The agency has long maintained that the nation’s public lands are over capacity with wild horses and burros, with an estimated 88,000 across the U.S., half of which reside in Nevada. 

The BLM has been criticized for some of its other population control methods, which include rounding up herds with helicopters, which advocates say is cruel and unfeasible for the long term. Some, like Neda DeMayo, founder and president of horse advocacy group Return to Freedom, have been pushing for more investment in fertility control measures. 

The agency’s Environmental Assessment outlines an experiment in which 16 “treated” mares and 16 untreated or “control” mares to be held in pens. Each pen will have four mares with one stallion. Researchers will assess the effectiveness of the vaccine over the next three years. 

Fertility programs are starting to be favored by advocates and federal officials alike. 

In December, Congress increased the BLM’s Wild Horse and Burro program budget by $21 million or 25%, with the contingency being that the agency invest its population control efforts to non-lethal practices like fertility control, The Washington Post reported.