Trace Minerals for California Beef Cattle 

University of California, Cooperative Extension

Siskiyou County Mineral Data

Selenium

Selenium deficiency is closely associated with soils of volcanic origin, and Siskiyou County soil is mostly of volcanic origin. Thus, it is not surprising that cattle in Siskiyou County are typically selenium deficient. This is supported with random sampling of 109 cattle in ten herds throughout the county with an average whole blood Se level of 0.036 ppm. This is considered deficient and responsive to supplementation.

Only one area of the county has been detected selenium adequate. Random samples from Scott valley had an average whole blood selenium level of .023 ppm (deficient), Shasta valley was .033 (deficient), and Butte Valley was .0465 (marginal). The higher value in Butte valley was due to two herds with 0.05 and 0.09 ppm Se (adequate). These herds were located on a dry ancient lakebed of non-volcanic soils (high organic matter). The average Se level for Butte valley without those two herds is 0.02 ppm Se (deficient). Thus, except for this isolated non-volcanic soil area, Siskiyou County is considered selenium deficient.

Cattle have been sampled from both improved pastures and non-improved high mountain meadows, with similar levels of Se deficiency. The most severe deficiencies are seen in late winter in lactating cows consuming hay.

Cattle that are not randomly selected, but sampled with some "bias" such as "poor" gains, lack of vigor, poor doers, have shown lower Se levels (average 0.029 n=289). Numerous individual cattle have had whole blood Se levels below 0.01 ppm.

Copper

Copper deficiency is less frequent and more localized than Se deficiency. From a random sample on any 10 cows in the county, about half would be expected Cu deficient. This contrasts with about 90 or more percent Se deficient.

Cu deficiency in Siskiyou County is usually a primary deficiency due to low copper with adequate, not excess, molybendum.  Random samples (5 samples per herd, 10 herds) had 0.48 ppm serum Cu which is deficient.  The average serum Cu level was 0.71 ppm for 78 samples selected from field trials and special case studies.  Samples sent to the Calif. Veterinary Diagnostic Lab (CVDL) from Siskiyou County had average serum Cu of 0.63 ppm.   These levels are between deficient and barely adequate. However, among those samples the lowest levels were 0.02 ppm, which is clearly deficient, while the highest was 1.19 (adequate). Liver samples at the CVDL averaged 217 ppm (deficient is below 100 ppm) but had a wide variation (SD 147).  Thus, there is variation in Cu levels.  There is a 50:50 chance of cattle being Cu deficient.  Sampling at individual ranches is needed to determine  Cu status.

Zinc

Zinc status is variable in the county. Some herds have all cattle within adequate range, while others have herd averages of 0.67 ppm. Generally below 0.8 is considered deficient. Deficient and adequate herds have been found in both Shasta and Scott valleys, and have not been tested in Butte valley.

Phosphorus

No conclusions are available regarding phosphorus status due to inadequate numbers of samples. Nine samples indicate adequate P levels of cows on grass/clover pasture. The legume (clover) component of the pasture would be expected to provide significant amounts of phosphorus.