Bioavailability of methionine hydroxy analog-free acid relative to DL-methionine in broilers

Three experiments were conducted to determine and validate the relative bioefficacy of the liquid form of hydroxy analog (liquid MHA-FA) to that of DL-methionine (Met) in male broilers. In experiments 1 and 2, 945 and 550 male broilers were fed either a Met-deficient basal diet, or the basal diet supplemented with four and five equimolar levels of each Met source, respectively. In experiment 3, 1232 male broilers were fed either a Met-deficient basal diet, or the basal diet with three levels (low, moderate, or high) of liquid MHA-FA or DL-Met at 65% of the liquid MHA-FA level. Growth performance improved in all trials, regardless of the Met source, relative to those broilers fed the basal diet. In experiments 1 and 2, the bioefficacy estimates for liquid MHA-FA relative to DL-Met on a product basis were: 50% and 64% for weight gain, 51% and 59% for the feed conversion ratio, and 54% and 48% for breast-meat yield, respectively. In experiment 3, there were no differences between the DL-Met or liquid MHA-FA treatments, and the broilers fed liquid MHA-FA were 68% as efficient on a product basis as those fed DL-methionine for weight gain. The results from these three trials indicate that the bioefficacy of liquid MHA-FA relative to DL-methionine is 57% on a product basis on average across all criteria tested.