Sodium status of crossbred Friesian X Zebu (Boran) calves fed roughage - based diets using faecal Na content as indicator

Studies the possibility of using faecal Na concentrations as an indicator of Na status in cattle. Two roughage-based diets composed of equal parts of roughage and concentrate were fed to Friesian X Zebu calves. The roughages were either oat-vetch hay or barley straw. Animals were grouped according to liveweight. Diets were fed individually for 98 days following a 14 day adaptation period when no Na Cl was provided. The calves fed the oat-vetch hay based diet given the highest level of Na showed higher live weight gain than the control grouVariation in salivary Na within each treatment was high and the effect of NaCl on the concentrations of salivary Na and K and Na/K ratio was not significant. Despite the Na supplementation, the concentration of Na in plasma in the calves fed either oat-vetch hay or barley straw based diets did not change. The effect of Na supplementation of faecal Na was significant for both diets. Concentration of Na in the faeces was below 1 g kg DM -1 only in the unsupplemented diets.