The steady increase in the price of protein feed ingredients and the retraction of antibiotics from diets has encouraged nutritionists to search the alternatives for protein source and functional feedstuffs that can substitute the role of antibiotic growth promoters in poultry production. With crude protein of 24-30%, in vitro protein digestibility of 80% and proportion of essential amino acids of 47%, seed from ripe papaya may be exploited as the alternative protein feed ingredient for poultry. Moreover, the growth promoting effect, antimicrobial and antiparasitic activities, and immunomodulatory and antioxidative activities may confirm the potential of papaya seed as a functional feedstuff that could replace the role of antibiotic growth promoters for poultry. The in-depth study is needed to further elucidate the functionalities of papaya seed on poultry. This review provides the updates on the nutritional contents of papaya seed, the potential of papaya seed as an alternative to conventional protein-rich ingredient, the growth-promoting effect of feeding papaya seed, the antimicrobial and antiparasitic activities of papaya seed, antioxidative activities of papaya seed, and the immunomodulatory activity of papaya seed on poultry.

Keywords: antimicrobial, antioxidant, antiparasitic, growth promoter, papaya by-product, protein-rich feedstuff.