Abstract: The objective of this study was to determine and compare seasonally the nutritive quality and mineral contents of diets by grazing steers during 2 consecutive years. For the statistical analysis a repeated measure design was used. There was not year x season interaction for Organic Matter (OM), Crude Protein (CP), Neutral Detergent Fiber (NDF), In vitro DM Digestibility (IVDMD) and Metabolizable Energy (ME) (p>0.05). Researchers found differences in CP content, IVDMD and ME between years (p<0.05). The higher values in these variables were registered in 2004. CP content was 20% higher in 2004. However, NDF content was 8% higher in 2005 that in 2004. There was not year x season interaction for the minerals evaluated (p>0.05). Nevertheless, the values of Calcium (Ca), Phosphorus (P), Sodium (Na), Potassium (K), Magnesium (Mg), Zinc (Zn), Selenium (Se), Manganese (Mn) and Copper (Cu) were different between years (p<0.05) and seasons (p<0.01). With the exception of P, the diet consumed for cattle throughout of the years and seasons had appropriate amounts of Ca, Na, K, Mg, Zn, Se, Mn and Co to meet requirements of beef cattle grazing native rangelands. The information generated in this study can be used for the formulation of protein, energy and mineral supplements according to the season of year.
M. Murillo Ortiz, E. Herrera Torres, O. Reyes Estrada, J.N. Gurrola Reyes and F.G. Rios Rincon, 2011. Spatio-Temporal Variations in Nutritive Quality and Mineral Contents of Diets by Grazing Steers in Native Range. Journal of Animal and Veterinary Advances, 10: 674-678.