Perfil mineral en bovinos lecheros de Santa Fe, Argentina

Abstract

Minerals are essential nutrients that represent 5% of the bovine liveweight. Lacks and disorders of minerals in animal nutrition affect the production, reproduction and health. In this assay, blood and milk were analyzed in 15 Holstein and Holstein-Friesian cows in four physiological states of three dairy farms with natural pastures from Las Colonias (Santa Fe, Argentina) during the spring and summer of 2006-2008. Poor edaphic conditions and low historical mineral composition of the soil characterized the area. Analysis of sera samples showed the following results: significant (p<0,05) Ca-deficiency related to physiological and productive requirements; hyponatraemia during the lactation period due to increasing demand for milk production; and during gestation hypomagnesaemia (p<0,05) due to stress of animals prior to birth and mineral loss through sweat during the summer. Significant (p<0,05) low values of serum zinc during pregnancy would be related to low temperature months. The analysis of milk samples from the dairy farms showed significantly (p<0,05) decreased average values of zinc, magnesium, calcium and potassium towards day 60 of lactation, which may be explained due to the utilization of minerals for milk production. The high concentrations of zinc in the grass antagonizes with the presence of high iron and molybdenum concentrations in the diet, condition observed in a dairy farm. We expect that our results may offer useful information to veterinarians and farmers of the considered geographical area.