Abstract
One of the supplements that can replace antibiotic growth promoters is a protein xanthophyll extract from the leaves of alfalfa. Green matter of alfalfa contains 17-22% of total protein, rich in non-essential (exogenous) amino acids, saturated, monounsaturated and polyunsaturated fatty acids, vitamins, minerals, and organic acids. The crude fibre content in green matter of alfalfa is relatively high (about 23.0-30.0% dry weight). However, protein-xanthophyll extract (EFL) contains about 1-2% of crude fibre. Like the whole plants of alfalfa, the protein-xanthophyll extract contains secondary metabolites such as plant phytoestrogens (isoflavones and coumestrol) and antinutritional components (phytates, L-canavanine and saponins). Protein-xanthophyll concentrate (PX) as a natural feed supplement has a positive effect on animal organisms. When supplemented to animals, this extract enhanced production results, increased feed efficiency, and improved the quality of meat, milk and eggs. Also, PX reduced methane emissions and soil pollution with nitrogen compounds when used in animal nutrition. The aim of this review was to gather the current literature describing the effects of using protein-xanthophyll extract in animal nutrition.