A macromineral survey of Louisiana beef cow-calf production systems

The survey purpose was to determine the state and regional macromineral status of Louisiana beef cow/calf production systems. Serum, forage, soil, and water were sampled from fall 2007 to spring 2009 at Louisiana beef-cattle operations (n = 25), which were divided into 7 regions (northwest, northeast, central, southwest, south central, Florida parishes, and southeast). Serum samples were collected twice annually in fall and spring, forage samples were collected quarterly, and soil and water were collected annually. The forage concentrations of Ca (0.42%); serum concentrations of Ca, Mg, Na, and S (9.0, 1.9, 303.3, and 103.3 mg/100 mL, respectively); soil concentrations of P, Na, and S (56.3, 88.4, and 29.7 mg/kg, respectively); and water concentrations of Na (84.7 mg/kg) were not different (P > 0.05) among regions. For all serum samples, less than 10% of Ca, 57% of Mg, and 14% of Na were less than reported lower critical levels in serum; 40% of Ca, 45% of P, small percentage of K, 70% of Na, and 7% of S were less than the minimum reported for appropriate nutrition in forage for beef cattle. All macromineral concentrations were above critical levels in soil as required for adequate plant growth. Water Na concentrations in regions northeast, southwest, south central, and Florida parishes were at desirable levels reported for livestock. Using serum as an indicator, the results indicated Louisiana cattle maintained adequate macromineral status and perhaps are partially reflective of the macromineral supplementation programs used throughout the state.