Performance of an Escherichia coli phytase expressed in Lactococcus lactis on nutrient retention, bone traits and intestinal morphology in broiler chickens.

Abstract

The availability of plant phosphorus in the gut chicken can be improved by increasing phosphorus retention using phytase enzyme or a probiotic with phytase activity as an alternative. In this study, the efficacy of a recombinant probiotic, Lactococcus lactis (L.lactis), with a potential of phytase production was evaluated in broiler chickens. To this aim, 360 one-day-old male broiler Cobb 500 were divided into six treatments with six replicates and reared to 42days of age. The experimental treatments included positive control diet containing adequate phosphorus (PC), negative control diet containing reduced available phosphorus (NC), negative control diet involving recombinant L.lactis (RLL), negative control diet containing both recombinant L.lactis and Lactobacillus salivarius (RLL+LBS), negative control diet including non-recombinant L.lactis (LL) and negative control diet containing Hostazym® . Growth performance, total tract apparent disappearance of phytate-P and nutrient retention, mineral content of the tibia and histomorphology of jejunum were evaluated at the age of 35days. Based on the results, the phosphorus (P) deficiency in the diet reduced body weight (BW), average daily gain (ADG), length and strength of tibia and increased feed conversion ratio (FCR) compared to PC group. However, the supplementation of Hostazym® or RLL probiotic into the feed improved BW, ADG, FCR, disappearance of Phytate-P and retention of P, length and strength of the tibia in a level similar to PC treatment. Phosphorus content of tibia in the chickens fed P-deficient diets containing RLL was similar to that of the tibia in the control group. Excreta phytate and total P excretion of the chickens decreased when diets contained Hostazym® , RLL and RLL+LBS. In addition, the diet containing RLL+LBS probiotic increased villi height compared with other treatments (p<.05). Further, recombinant L.lactis could represent phytase activity in the gut environment of the chickens and could be an alternative to the commercial phytase.