effects of dietary threonine and a multi strains probiotic (primalac) supplementation on growth performance, blood metabolites and carcass characteristics in japanese quails

the objective of this study was to investigate the effects of three levels of threonine (100, 95 and 90% of nrc requirements) with or without of multi strains probiotic (primalac) on performance, carcass characteristics and blood metabolites of japanese quails. a total of 180 one-day-old male japanese quails were randomly allocated to six treatments with three replicates and 10 birds per each. the experiment was done from 0 to 6 weeks of age. growth performance traits including weight gain, feed intake and feed conversion ratio were recorded. at the end of the experiment, six birds per treatment were slaughtered and carcass characteristics were measured. blood sampling was taken at 42 days of age. the results of this study indicated that supplementation of probiotic did not affect feed intake, weight gain and feed conversion ratio in quails. in contrast, feed conversion ratio was improved in birds fed with 100% of threonine requirements. all carcass traits, except for liver weight, were not influenced by threonine levels and dietary probiotic supplementation. the liver percentage was higher in birds fed diets without the probiotic. the results showed that serum glucose was affected by threonine levels. however, the other blood metabolites such as cholesterol, triglyceride, high-density lipoproteins and low-density lipoproteins were not influenced by the threonine levels. in this regard, none of the blood metabolites were influenced by probiotic supplement, except for cholesterol. in conclusions, the supplementation of probiotic did not affect growth performance in japanese quails. however, use of threonine at 100% nrc requirements improved feed efficiency in japanese quails.