A mineral survey of Louisiana beef cow/calf production systems

Abstract

The purpose of this research was to determine the state and regional mineral status of Louisiana forages and beef cattle. Louisiana beef cattle operations (n = 25) were sampled and divided into seven geographical regions, including the northwest (NW), northeast (NE), central (CE), southwest (SW), south central (SC), Florida parishes (FP) and southeast (SE) regions. Over a two year period, water and soil samples were collected from each operation annually, forage samples were collected quarterly in Aug to Sep, Nov to Dec, Feb to Mar and May to June and bovine serum samples were collected twice annually in the fall and spring seasons. The highest (P < 0.05) average regional water K and S concentrations were observed in the SE region and water Ca and Mg concentrations were the highest (P < 0.05) in the NE, CE and SE regions. However, all water mineral concentrations, with exception of Na, were lower than the reported upper desired levels considered safe for livestock consumption (Socha et al., 2003). Similar to water, soil Ca, Mg and K concentrations in our study, were higher (P < 0.05) in the SE compared to all other regions. Soil Cu concentrations were below critical levels in the CE region and all soil Zn concentrations, except the SE region, were lower than reported critical levels indicating soil deficiency. The average forage concentration for each mineral were: Ca (0.42%), P (0.28%), Mg (0.21%), K (1.83%), Na (0.10%), S (0.32%), Cu (8.12 ppm), Fe (323.46 ppm), Mn (254.85 ppm) and Zn (41.29 ppm). In addition, only mean forage Cu concentrations were lower than minimum requirements and regional forage K (NW region), Mg (FP region), Na (CE region) and S (NW and SE regions) concentrations were higher (P < 0.05) than other regions. The average regional serum K concentration in the NE region was higher (P < 0.05) than all other regions. Average bovine serum mineral concentrations in Louisiana were: Ca (9.02 mg/100 ml), P (13.62 mg/100 ml), Mg (1.92 mg/100 ml), K (21.66 mg/100 ml), Na (303.30 mg/100 ml), S (103.31 mg/100 ml), Cu (0.63 µg/ml), Fe (7.44 µg/ml), Zn (1.28 µg/ml), Mn (8.08 ng/ml) and Se (64.48 ng/ml). Furthermore, of these minerals, serum Mg, Na, Cu and Mn concentrations were lower than critical levels, indicative of deficiency.