Serum and Tissue Sodium (Na) and Potassium (k) Concentrations in Newborn, Growing and Adult Sheep

Little is known of the physiological Na and K tissue changes from birth to adulthood in sheep and other livestock. The purpose of this study was to compare the changes in the sodium and potassium contents of liver, kidney and brain tissues in newborn lambs with those of growing and adult sheep tissues. Serum, Liver, kidney and brain tissue samples were taken from 32 newborn lambs, 20 growing lambs (mostly about 6 months), and 25 adult (2-6 years) from various farm locations of Central Trinidad. All mineral determinations were carried out on a Pye Unicam SP2900 Atomic Absorption Spectrophotometer. Serum N and K levels were not significantly different (P> 0.05) in new born lambs compared with levels in growing lambs and adult sheep. Higher Na levels but lower K levels were found in liver, (P<0.001) and brain (P<0.001) tissues of new born lambs compared with levels in growing lambs and adult sheep. Only a few animals had concentrations within the expected ranges for liver Na (35-39 m.Eq/w.wt) and liver (78-86 m.Eq/w.wt). K: Na ratios in liver tissues were about the value expected for ruminants of 2:1 which contrasted with ratio of unity found in newborn lambs. Preliminary indications from this study implied that not only was there a reversal of Na and K levels in liver but also in brain tissues of newborn compared with growing and adult sheep.