Analyses of Louisiana and Mississippi Producers' Samples Reveal Mineral Status of Forages

Abstract

Feed value analysis results of Louisiana and Mississippi forage samples categorized into cool-season annual grass (CSAG), cool-season legume forage (CSLF), volunteer warm season grass (VWSG), warm-season annual grass (WSAG), and warm-season perennial grass (WSPG) were reviewed focusing on mineral contents, hypomagnesemic tetany potential, and correlation between the organic nutrients and minerals. Except for high K concentrations in all forage types, macro-mineral concentrations of Ca, P, and Mg were marginal in meeting the mineral requirements of actively growing cattle. Percentages of forage with tetany ratio greater than 2.2 were 20.0, 0.0, 10.3, 4.8, and 4.5% in CSAG, CSLF, VWSG, WSAG, and WSPG, respectively. The correlation coefficients between CP and P, Mg, or K were generally positive while those between NDF and the minerals were mostly negative. Results of producers' forage samples revealed deficiencies of most macro and micro-minerals, and significant chances of hypomagnesemic tetany. Producers' long-term sample analysis results did not provide any strong correlation between minerals and energy or protein. Therefore, sample analysis will be necessary to cover micro and macro minerals in addition to energy and protein. Potassium fertilizer management decisions will need to be made carefully based on analysis results of soil and plant tissue.