22 March 1996

Sodium deficiency could be avoided

WHEN sodium is deficient, increasing the concentration in forage reduces milk cell counts.

That is particularly beneficial in low yielding cows, where somatic cell outputs are greater than in high yielding cows. An increase in the sodium:potassium ratio in grazed herbage may also increase the milk yield of low yielders by improving palatability and intake.

Work by Phillips, Chiy and Arney, Cambridge Vet School, exp lained that grazing dairy cows risk sodium deficiency because of the large output of sodium in milk and the low sodium levels in forage.

When mastitis strikes, plasma containing sodium, chlorine, immunoglobulins and other blood proteins leaks into the udder and secretion declines. The sodium content of mastitic milk is usually increased by 150 to 300%, which helps limit the growth of bacteria like Streptococci, which are sensitive to sodium concentration.