Livestock obtain forage by grazing on rangeland. In California annual rangelands, residual dry matter is commonly used to determine proper grazing levels. Rangeland forage biomass and quality can degrade dramatically during the dormant summer period. We examined 25 sites across an annual rainfall gradient (183-492 mm) over 3 contrasting rainfall yr (2015-2017) that varied from 57% to 152% of average annual precipitation. Overall fractional biomass loss was 54.4% (range = 46.5-61.5%) with greater fractional losses occurring in dry years. Biomass losses were related to the amount of peak standing crop and plant composition-both a function of annual precipitation. Fractional seasonal losses from the peak standing biomass in 2015 = 962 kg/ha (61.5% seasonal; 9.7% monthly), 2016 = 1 541 kg/ha (55.0% seasonal; 8.7%monthly) and 2017 = 1 923 kg/ha (46.5% seasonal; 7.3%, monthly). Forage quality metrics were strongly affected by summer weathering processes. Crude protein concentrations decreased by 33. 6%, 27.7%, and 21.0% in 2015, 2016, and 2017, respectively. In contrast, relative concentrations of fiber and lignin (acid detergent fiber [ADF] = cellulose + lignin) and in the weathered biomass showed increases for

Cattle play an important role in wildfire management by grazing fuel on California rangelands. The benefits of cattle grazing have not been thoroughly explored, though. Using statewide cattle inventory, brand inspection and land use data, we have estimated that cattle removed 11.6 billion pounds (5.3 billion kilograms [kg]) of non-woody plant material from California's rangelands in 2017. Regionally, these reductions varied between 174 and 1,020 pounds per grazed acre (195 to 1,143 kg per hectare). Fire behavior is characterized in this paper by flame length. Fire behavior models suggest that these regional fuel reductions lower flame lengths, and lead to more manageable wildfires. In addition, fire-based models show that cattle grazing reduces fuel loads enough to lessen fire hazards in many grazed areas. Moving forward, there may be significant opportunities to expand strategic grazing on rangelands to add extra layers of protection against wildfires.

Optimal mineral nutrition is required for cattle reproduction, immune function, and structural development. Formal evaluation of the current mineral status of California beef cattle is currently lacking. In 2017, a survey was initiated that evaluated a panel of 10 different minerals in 14 counties across California. Samples were collected from 555 cattle at 50 different ranches. Region of the state significantly affected herd mineral status. Herd use of supplements was also significant, and increased most blood levels of the mineral(s) targeted for supplementation. Forage source was idiosyncratic on its effect of mineral status. Previous blood survey data showed selenium to be widely deficient in California cattle in the 1970s and 1980s, but in this case, it was generally adequate in all areas of California. This indicates a good producer understanding of where supplementation is needed. Copper deficiency was more widespread in the southern region when compared with further north. Zinc deficiency was seen ubiquitously statewide, with 36% of animals being deficient. Manganese has been largely ignored in California. This study is the first known documentation of manganese levels in the state. Sampling found 92% of cattle fell below critical manganese levels. However, further research to better define manganese critical levels is probably warranted. The status of other minerals is presented.

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