effect of l-threonine supplementation of wheat based diet on immune response, small intestinal morphology, and blood parameters of japanese quails

this experiment was performed in order to determine effects of different levels of dietary l-threonine supplementation in male japanese quails’ diets on immune response, small intestinal morphology, blood parameters and microflora.one hundred and forty four, 1-d old japanese quails have been selected and randomly distributed between six treatments and four replicates. basal ration was based on wheat, without supplemental threonine and other treatments were supplied by 0.6, 1.2, 1.8, 2.4 and 3.0 g/kg l-threonine. serum antibody titer at 7 days after injection of sheep red blood cells was significantly increased by threonine levels (p<0.01). serum antibody titer at 7 days after injection of newcastle vaccine and cellular immune status was not influenced by theronine supplementation. the results showed that supplemental l-threonine in different levels have not significant effect on serum uric acid but increased serum albumin, serum calcium, serum cholesterol, low-density lipoproteins (p<0.01) serum total protein values (p<0.05) and decrease triglycerides values (p<0.01). a linear increasing of villi height and decrease crypt depth was indicated by increasing supplemental threonine levels (p<0.01). a linear increasing of lactic acid bacteria and decrease coli bacilli and total bacteria was indicated by increasing supplemental threonine levels (p<0.01). supplementation 2.4 g/kg l-threonine of quails’ diets containing non starch polysaccharide improved humoral immune responses and 2.4 and 3 g/kg showed the favorite effects on increase villi height, ileum useful bacteria and decrease crypt depth.