A simple and rapid method for collecting saliva to assess sodium status in sheepum

Abstract

Fifteen lambs were fed diet with normal (0.11%) or deficient levels of sodium ( 0.035%), respectively, for five weeks on each diet. At the end of each period saliva was collected by three different methods: swabbing with a 5 x 5 x 1.25cm synthetic sponge, aspiration with a 15cm long plastic tube connected to a 20ml syringe and sucking with a 4mm x 45cm long plastic tube through a water-jet aspirator pump or an eletric motor pump. The volume of saliva collected/min and the salivary sodium: potassium ratio were analysed. Larger volume of saliva was obtained with the developed sucking apparatus than with the sponge or the syringe. There was no influence of the method of saliva collection on the values of salivary Na:K ratio in both periods. Nevertheless, the lower the sodium dietary level was, the smaller the salivary Na:K ratio. Five weeks of low sodium diet intake resulted in a decrease in the salivary Na:K ratio values by half. However, the lambs did not exhibit any clinical sign of sodium deficiency. The advantages of the developed method to collect saliva are discussed.