Specimens: Urine (or pasture/ diet)
Optimum number of animals to test for mob/herd/flock deficiency: 8-10
In lactating dairy cattle sodium requirements are high. Deficiency signs are reported to include poor conception rates, irregular oestrus cycles and poor milk yield. Because of homeostatic mechanisms the measurement of serum sodium gives erroneous results. The measurement of the potassium (mmol/L):sodium (mmol/L) ratio in urine appears to overcome these problems.
Reference Interval: A median K:Na ratio of <15 suggests a sodium deficiency in a mob of cattle.
Reference: Eicher et al. Evaluation of biochemical methods for estimating the sodium intake of dairy cows. Veterinary Record 153:358-362, 2003.