8 March 1996

Vitamin A – vital to disease prevention

UK calf producers have been urged to watch out for symptoms of vitamin A deficiency in calves born in late winter and early spring.

The warning comes from British Denkavits Will Sinclair, who says that vitamin A deficiency seen in these calves is linked with the incidence of scour and death being at least six times greater at this time of year.

"Problems are most common in winter because of the poor availability of vitamin A to the dam," says Mr Sinclair. "The dam can be many months away from carotene – the precursor of vitamin A – obtained from fresh green forages. Cows are also inefficient in passing vitamin A through the placenta to the foetus."

Vitamin A is essential for rapid growth and, in particular, disease prevention. This is because it contributes to the manufacture and maintenance of the epithelial tissue of the inner and outer surfaces of the body – important barriers to pathogens.

"This fine structure acts as a first line of defence to invasion of any pathogenic organisms," he says. "It is not only associated with the condition of the outer skin, but even more with the walls of the digestive tract and the respiratory system. As a result of vitamin A deficiency, the epithelium cells are dry and scaly, so they are easily broken down and penetrated, making the body vulnerable to attack.

"Supplementary vitamins, including vitamin A, are therefore essential for the ability of the calf to resist disease and maintain healthy growth rates," he says. &#42


SYMPTOMS


&#8226 Poor growth rate and appetite.

&#8226 Dry dull coat.

&#8226 Weeping eyes and nasal discharge.