Hayvan besleme ay1smdan btiyiik oneme sahip olan yem katki maddelerinden en 9ok kullan1lanlar A.r. itibiotikler ve Hormonlard1f. Bulunuu eski olmasma ragmen, kullarnm1 yeni olan bir  diger yem katkI maddesi ise probiotiklerdir .Probiotikler, arzu edilmeyen mikroorganizmalarm gelimelerini engellemesi ve bakteriyel ek yem olmas1 ay1smdan onem talf. Aynca yemlere ilave edildigi.nde canh agIThk:, yem tiiketimi, yeitli verimler ve saghk iizerine olumlu etkileri goriilmil r. Diger yem katkI maddelerinin bulunmad 1g1 yerlerde probiotikler kullamlabilir.

Feed additives have great important from animal nutrition. Point of view, Antibiotics and Hormons are among the most used feed additives . Although it was available in ancient years, a new used feed additive is Probiotics.The Probiotics have special role with respect to preventing undesired microorganisms. they are also fungal additive feeds . On the other ha,nd, when added to the feeds, their possitive effect on the feed consumption, live weight, yield and animal health have been found. Where other feed  dditives are notavailable, probiotics can be used .