Trace Minerals for California Beef Cattle 

University of California, Cooperative Extension

Modoc County Mineral Data

Selenium deficiency is closely associated with soils of volcanic origin, and Modoc County soil is mostly of volcanic origin. Thus, it is not surprising that cattle in Modoc County are typically selenium deficient. This is supported with random sampling of 40 cattle in four herds throughout the county with an average whole blood Se level of 0.042 ppm. This is considered just barely deficient and responsive to supplementation. Two herds from the Tulelake area were lower at about 0.025 ppm. Thirty five additional samples from field trials had an average whole blood value of 0.045 ppm.

Copper status can be highly variable for ranches located near each other. Two herds located near Alturas had serum Cu levels of 0.47 (deficient) and 1.13 (adequate) ppm. Similarly large differences were found in Tulelake (0.245 - very deficient, 0.550 marginally deficient). Overall 20 samples taken at random from 4 herds had an average serum copper of 0.74 ppm which is only marginally deficient.

Cattle selected for field trials and as potential sites of copper deficiency (rather than purely random samples) had average serum Cu of 0.58 ppm (marginally deficient).

Class 3 liver samples showed high variability suggesting some cattle Cu deficient.

Copper deficiency should be suspected throughout the county, but status can be highly variable at nearby locations. Sampling at specific sites is therefore very important.

Based on 130 samples from 6 herds, zinc is usually adequate in Modoc County. Of the 6 herds, no herds were deficient.

No conclusions are available regarding phosphorus status due to lack of available data.