study of a recombinant lactococcuslactis performance to degrade of phytate phosphorus in broiler chick diets

introduction phytic acid is a main compound in all plant seeds and contains 60 to 70% of total phosphorus in plant. monogastric animals cannot use phytatephosphorus because of low phytase activity in their digestive tract. thus in addition to unabsorbed mineral phosphorus, phytate phosphorus in fecal ofmonogastric animals may affect water and environment pollution. it is suggested to use of phytase enzyme for resolving of this problem. phytase activity was showed in some bacteria like pseudomonas, bacillus subtilis and amyloliquefaciens. few strain of lactic acid bacteria order showed phytase activity or were different for this activity. on the other hand these bacteria order are important as probiotic strains. there are numerous studies to use probiotic bacteria with specific enzyme activity for increasing nutrient availability to animals. this experiment was aimed to study of a recombinant lactococcuslactis performance to degrade of phytate phosphorus in broiler chicken diets. materials and methods lactococcuslactis was supplemented to a phosphorus deficient diet (50% of available phosphorus recommended by nrc) lonely or with two other lactobacillus bacteria (lactobacillus crispatusand lactobacillus salivarus) in rate of 108 cfu/g diet. diets were also formulated with recommended available phosphorus by nrc with or without probiotic supplementation. two hundred eighty eight one day old male ross broiler chicks were subjected to 6 experimental treatment in 4 replicates and 12 chicks in each replicate. growth performance, bone characteristics, intestinalmicroflora, and blood metabolites were measured. apparent phytate digestibility was estimated by chromic oxide marker method. the chromic oxide was added in rate of 0.3% ofthediets. phytate phosphorus was measured by the method of wheeler et al (1971). on day37, level of calcium, phosphorus and cholesterol of serum were measurement by bleeding from wing vein. left thigh bone was isolated on 42 days and its dimensions and strength were measurement by caliper and instron instruments respectively. results and discussion body weights of deficiency phosphorus treatments showed significant decrease even in presence of recombinant probiotic (p<0.01). the use of mixed probiotics in treatments containing both level of available phosphorus showed digestibility of phytate phosphorus around % 20 higher than no probiotic treatments and, the treatments supplemented with lactococcuslactis displayed higher phytate phosphors digestibility around %18 compared to control, although there was no significant difference. the serum phosphorus of chicks fed diets contained mixed probiotics showed an increased trend relation to no probiotic treatments (p=0.0603). the mean of thigh bone length was decreased in phosphorus deficiency, diet supplemented with l.lactis alone and, no probiotic treatments significantly (p<0.05). in 42 days age, lower gram negative bacteria were determined in the flora of chicken’s caecum that used probiotic supplement but there was no significant difference. the mix probiotic treatment trends more effective than only l.lactis on reduction of gram negative population (p<0.1). the results of this study declared that use of recombinant lactococcuslactis may increase phytate phosphorus digestibility but low level of phytate phosphorus in diets and not enough increase in phytate digestibility didn’t supply phosphorus requirement in chicks. phosphorus level in serum of chickens feed by mixed probiotic bacteria showed that probably presence of lactobacilli accompany to l.lactis could improve efficiency of phytate degradation, because lactobacilli activity increased solubility of phytate by acid production and it could exposesphytate to phytase enzyme. since the ideal activity of produced recombinant phytase is under acidic ph, then lactobacillus bacteria improved condition of intestine for recombinant phytase activity. considering to the level of phytate p of diet with phosphorus deficient showed that phytase activity couldn’t supply p requirement of chickens while the digestibility of phytate p was determined 63%. therefore lower growth in mentioned treatment was not avoidable. decrease of the thigh bone length in chickens fed by no probiotic or l.lactis treatments reflected low phytase activity and low phytate contain in diet. also in treatments contain probiotic, appropriate bone dimensions (diagonal of epiphyses and diaphysis and length of bone) may attributed to better calcium absorbance in presence of lactic acid bacteria. it is showed that use of probiotic produces short fatty acids in intestine. it can stimulate villi growth and production of calcium binding protein in enterocyte cells. in this study, reduction of gram negative bacteria population were excepted since anti- e.coli and salmonella activity of mix probiotic was showed. conclusion based on this study, it is suggested to develop of phytase gene expression in lactococcuslactisby supplemental study and use of probiotic lactobacilli as same time.