Cowboys Wyatt Williams (R) and David Thompson work to restrain a calf in order to give it medicine near Ignacio, Colorado June 12, 2014. The land where the cattle graze is leased from the Forest Service by third-generation rancher Steve Pargin. Several times a year, he and a crew led by his head cowboy, David Thompson, spend a week or more herding cattle from mountain range to mountain range to prevent them from causing damage to fragile ecosystems by staying in a single area too long. (Photo by Lucas Jackson/Reuters)

An Indian woman collects camel dung during the annual cattle fair in Pushkar, in the western Indian state of Rajasthan, Sunday, November 10, 2013. Pushkar, located on the banks of Pushkar Lake, is a popular Hindu pilgrimage spot that is also frequented by foreign tourists who come to the town for the annual cattle fair and camel races. (Photo by Ajit Solanki/AP Photo)

Cows belonging to Samburu tribesmen walk around the carcass of an elephant killed by armed cattle herders in Mugui Conservancy, Kenya February 11, 2017. Kenya has declared the ongoing drought affecting many parts of the country a national disaster, calling for aid to counter the situation which is posing a major risk to people, livestock and wildlife. (Photo by Goran Tomasevic/Reuters)

A man from Dinka tribe holds his AK-47 rifle in front of cows in a Dinka cattle herders camp near Rumbek, capital of the Lakes State in central South Sudan December 14, 2013. (Photo by Goran Tomasevic/Reuters)

A jockey takes part in a traditional cattle race or “Pacu Jawi”, to mark the end of the rice harvest in Tanah Datar, West Sumatra, Indonesia, August 13, 2016 in this photo taken by Antara Foto. (Photo by Hafiz Mubarak A./Reuters/Antara Foto)

Cattle are the most important way of livelihood for the Karamojong: they provide milk, meat, blood and money when sold, Karamoja, Uganda, February 2017. (Photo by Sumy Sadurni/Barcroft Images)

A man waits with his camel to take part in a camel decoration competition at the Nagaur Cattle Fair, where animals like camels, cows, horses, and bulls are brought to be sold or traded, in Nagaur, in the desert state of Rajasthan, India February 2, 2017. (Photo by Himanshu Sharma/Reuters)

An armed man herds his cattle close to the village of Nimini in northern South Sudan, February 8, 2017. In the chaos of South Sudan's civil war, it took three years for Nyagonga Machul to find her lost children. Machul had traveled from her village to the capital when President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer, in 2013. (Photo by Siegfried Modola/Reuters)