Comparsion Of Relative Bio-efficacy And Metabolism Of Liquid Methionine Hydroxy Analogue Free Acid To DL-methionine In Broiler Chicken

Methionine is a limiting amino acid in commercial poultry diets and is commonly supplemented as dry DL-methionine (DLM, 99% pure) or as liquid methionine hydroxy analogue free acid (MHA-FA, containing 88% of active substance). Knowing the relative bioefficacy of MHA-FA is an important precondition to cost-effective purchasing, feed formulation, animal production. Thus, two broiler experiments were conducted: experiment 1 was focused on assessing the bioeffiacy of liquid MHA-FA relative to DLM;further, experiment 2 was performed to study the absorption and metabolism of liquid MHA-FA compared to DLM in order to elucidate the mechanism of differences in bioefficacy.Experimentl. Comparison of Bio-efficacy of Liquid Methionine Hydroxy Analogue Free Acid Compared to DL-Methionine in Broiler ChickenThis experiment was conducted to assess relative bio-efficacy of liquid methionine hydroxy analogue-free acid (MHA-FA) and DL-methionine (DLM) in broiler chicken. Exponential regression method was employed to determine biological efficacy based on weight gain, feed conversion, and carcass yield responded to dietary methionine sources. A total of 990 male broilers at the age of 7 days were allocated into 11 treatments randomly, each consisting of 6 replicates, with 15 broilers of each replicate. Five graded inclusion levels of DLM (0.030%, 0.060%, 0.100%, 0.150%, 0.210%) and liquid MHA-FA (0.034%, 0.068%, 0.114%, 0.171%, 0.239%) were respectively added to a basal diet that met the nutrient and energy requirements of broilers, except for Methionine+Cyseine. In the period of 7 to 42 days , broilers responded to the dietary treatments significantly (P<0.05). Regression analysis revealed the liquid MHA-FA was 59.5% (weight gain), 74.2% (feed conversion), 81.7% (carcass yield), 78.4% (breast yield) as efficacious as DLM on the equimolar basis.Experiment 2. Metabolism of Liquid Methionine Hydroxy Analogue Free Acid Compared toDL-Methionine in Broiler ChickenThis experiment was conducted to compare the absorption and metabolism of DL-methionine and liquid methionine hydroxy analogue free acid on the broiler chickens. A total of 280 male 1d old broilers was allocated into 7 treatments randomly, each composed of four replicates, with 10 broilers of each replicate. Three graded inclusion levels of DL-methionine (0.030%, 0.100%, 0.210%) and liquid MHA-FA (0.034%, 0.114%, 0.239%) were respectively added to a basal diet that met the nutrient and energy requirement of broilers, with an exception of methionine+cysteine. On the 15d, Cr₂O₃ was added to the diets as an indicator to calculate the absorption rate of DLM and liquid MHA-FA. On the 21d, 6 broilers were randomly sampled from each replicate and euthanized, and their intestinal tracts and liver were sampled. HPLC was employed to examine the residual DLM and liquid MHA-FA in the intestine tracts, and the metabolites (S-adenosylmethionine, S-adenosylhomocysteine, homocysteine,cystathionine, cysteine) of DLM or liquid MHA-FA in the broiler liver. The results indicated that net absorption rate of DLM of three graded levels (0.030%, 0.100%, 0.210%) were 96.3%, 95.3% and 96.6%, which is significantly higher (PO.05) than MHA-FA (89.5%, 87.0% and 86.4%) of corresponding level (0.034%, 0.114% and 0.239%), respectively. The supplementation of DLM and liquid MHA-FA significantly increased the level of homocysteine and cysteine in the broiler liver (PO.01). The concentration of homocysteine of the 0.100% and 0.210% DLM group were significantly higher than the corresponding level of liquid MHA-FA based on an equimolar (PO.05). SAM, SAH and cystathionine were not significantly responded to the supplementation of Met sources (P>0.05). The metabolite concentration of liquid MHA-FA in the broiler liver, however, was generally lower than that of DLM. This experiment revealed that liquid MHA-FA can not be absorbed or metabolized so efficiently as DLM by the broiler chicken.In conclusion, the bioefficacy of liquid MHA-FA was lower than DLM, the differences observed in the absorption and metabolism confirmed that liquid MHA-FA can not be utilized by broiler chicken as efficiently as DLM.