Sulfur-Induced Copper Deficiency in the Yaks

Since the 1990s, yak in the Haizi area in China has been affected by an ailment characterized by pica, emaciation, dyskinesia, and anemia. To determine the cause of disease, the mineral composition of soil and forages, and samples of blood, hair, and liver of yaks from the Haizi area in China were determined. The concentrations of copper in soil and forage from affected ranches and unaffected areas are within the normal ranges. The mean concentration of copper in blood and liver from the affected yaks was (0.31 ± 0.03) and (13.7 ± 3.1) μg g-1, respectively, compared with (0.98 ± 0.16) and (95.6 ± 11.2) μg g-1 for unaffected yaks. The concentrations of sulfur in soil and forage from affected ranches were (1.91 ± 0.26) and (1.37 ± 0.17)%, respectively, compared with (1.11 ± 0.31) and (0.52 ± 0.18)% (dry matter) for normal areas. The contents of sulfur in blood and liver affected animals were (7.32 ± 1.8) and (2.54 ± 3.1)%, respectively, compared with (4.22 ± 0.73) and (1.31 ± 0.33)% (in fresh and soft tissues) for healthy animals, respectively. Oral administration of tribasic copper chloride prevented and cured the disease. Thus it is reasonable to conclude that ailments of yaks in the Haizi area are probably caused by a secondary copper deficiency, mainly due to high sulfur content in soil and forage.