Probiotic Lactococcus lactis subsp. lactis and chitin supplementation in the common carp Cyprinus carpio diet and their influences on growth performance, body composition and feed digestibility

Probiotic and prebiotic have many advantages and are employed as a method for aquaculture yield improvement. The main goal of the current study is to evaluate the effect of dietary Lactococcus</em> lactis </em>subsp. lactis</em> as well as chitin on growth performance, carcass composition and feed digestibility in common carp, Cyprinus carpio</em>. So that, 360 juvenile carps with mean initial weight of 12 ± 1.5 g were randomly distributed in 6 treatments based on adding different chitin levels including 0, 1, and 2% and probiotic including 0 and 2% (1×107</sup> CFU/g) to a basal diet and cultured for 8 weeks. At the end of the experiment, growth indices, survival rate, carcass composition and nutrient digestibility were measured. Maximum final weight, weight gain, feed conversion ratio, daily growth rate, feed efficiency and condition factor as well as the lowest FCR were observed in treatments fed with probiotic 2%, chitin 1% and probiotic 2% + chitin 1% (P<0.05). Dietary chitin and probiotic did not alter feed intake and total length in common carps (P>0.05). The experimental treatments did not influence the carcass composition and nutrient digestibility. In conclusion, it seems that adding 2% probiotic and 1% chitin can improve some growth indices in common carp, but can not affect carcass composition and nutrient digestibilty.