bio-efficacy comparison of herbal-methionine and dl-methionine based on performance and blood parameters of broiler chickens

this study was conducted to compare the bio-efficacy of herbal methionine (h-met) relative to dl-methionine (dl-met) on 160 “ross 308” broiler chickens. dl-met and h-met were added to the basal diet in eight experimental treatments with three and four concentrations respectively in starter, grower and finisher period. blood parameters which were measured at 24 and 42 days of age consisted of: serum proteins (total protein, albumin and globulin), serum uric acid, serum fats (low density lipoprotein, high density lipoprotein, triglyceride and cholesterol) and serum enzymes (alanine amino transaminase and aspartate amino transaminase). completely randomized design, multi-exponential and multilinear regressions were used to determine bio-efficacy of h-met in terms of performance and blood parameters of broilers. the results showed that supplemented methionine (met) sources had no significant effect on blood parameters at 24 day of age. at 42 day of age the amounts of globulin and serum high density lipoprotein (hdl) increased with supplemented met, (p < 0.05). regression analysis revealed that h-met was 55.00, 71.00, 78.00, 47.00, 58.00 and 73.00% as efficacious as dl-met for body weight gain, feed intake, feed conversion ratio, albumin, globulin and high density lipoprotein criteria, respectively. the average of bio-efficacy of h-met compared to dl-met was 67.00% and 59.00% on average across performance criteria and blood criteria respectively and was 63.00% across these two criteria tested. the results of the present study indicated that h-met can be administered as a new and a natural source of met in poultry industry.