Murdo Mackenzie, cattleman, was born near Tain, County Ross, Scotland, on April 24, 1850, the second of eleven children of tenant farmers David and Jessie Mackenzie. He attended parish school until 1864 and graduated from the Royal Academy at Tain in 1869. He served as an apprentice in a law office and then in the British Linen Bank at Tain. A bank customer, John Forsyth, hired Mackenzie as assistant factor for the Balnagown estate of Sir Charles Ross; Mackenzie held this position for about ten years. On January 14, 1876, he married Isabella Stronach MacBain. They had five children. In 1885 an Edinburgh syndicate offered him the managership of the Prairie Cattle Company, and the Mackenzies moved to Trinidad, Colorado. He became an American citizen as soon as he was eligible and served as mayor of Trinidad. In 1891 he accepted an offer to manage the Matador Land and Cattle Company; he became well known for improving the Matador's herd, especially by introducing purebred Hereford bulls and sending young steers to northern ranges. Mackenzie was president of the Texas and Southwestern Cattle Raisers Association from 1901 to 1903. He then became founding president of the American Stock Growers Association (later the American National Live Stock Association) and served from 1905 to 1911. During this time he testified before the Interstate Commerce Commission and congressional committees and in interviews with President Theodore Roosevelt presented evidence that was instrumental in the passage of the Hepburn Act of 1906, which secured fairer railroad rates for western shippers. Roosevelt appointed him to the National Conservation Commission in 1908.
In 1912 Mackenzie left the Matador to accept the managership of the Brazil Land, Cattle, and Packing Company, an enterprise backed by French money. Out of São Paulo he acquired and stocked ten million acres of land for his employers. His stay in South America during World War I constituted what he later termed the most interesting and gratifying experience of his life. At the expiration of his five-year contract with the French syndicate he returned to the United States in 1918 and was promptly elected to the Matador board of directors. In 1922, when Matador manager John MacBain died unexpectedly, Mackenzie was reappointed to the position he had previously held. During his second tenure at the Matador he worked with Thomas E. Wilson to improve relations among those involved in the meat-packing industry. Declining cattle prices and changing tastes in the American diet during the 1920s caused Mackenzie to recommend to the Matador shareholders that the company abandon its northern pastures as leases expired and confine its operations to its two Texas divisions. The program was adopted and implemented, so that by the end of 1928 the withdrawal to northwestern Texas had been completed. Mackenzie continued in management affairs until his retirement in 1937, when his son John took over. He died on May 30, 1939, in Denver and was buried there.