Zinc in Animal nutrition

Zinc is one of the essential trace elements for man and animals and performs numerous vital functions in the body. Due to the wide spectrum of functions Zn deficiency can give rise to a variety of different symptoms. These range from growth depression, disturbed on delayed sexual and reproductive development, parakeratotic skin lesions, weakening of the immune system and delayed wound healing through to hair loss and growth stop with serious impairment of general health. Severe Zn deficiency states are rare in practical animal nutrition. Of greater importance are probably the marginal undersupply situations which can also be induced by a variety of factors (certain dietary constituents, drugs, diseases of the liver, the kidneys or the intestine, infections, pregnancy, etc.). The Zn content in the total ration for virtually all livestock species and types of production should be 50 mg/kg dry matter (twice as much for piglets). It is unlikely that these levels can be supplied through practical rations alone, without Zn supplementation via a suitable mineral additive because all the conventional forage types for cattle and the principal components of concentrate mixtures for cattle and pigs such as cereals, roots and beet pulp, extracted oil meals, expellers and milling by-products either contain too little zinc or have poor Zn availability, Although animal-derived feedstuffs could have beneficial effects both with regard to their Zn concentration and its availability, their use is in most cases not an economically viable proposition. For the diagnosis of marginal Zn deficiency states Zn analyses of serum or hair are not very suitable due to homeostatic control mechanisms or insufficient dynamics. A more effective diagnostic tool is the analysis of biochemical criteria, of which the determination of alkaline phosphate activity by means of a response technique with oral zinc or zinc injections and the Zn binding capacity of the serum constitute two simples and sensitive criteria for assessing the Zn status of an animal