A comparison of methionine sources for broiler chickens fed corn-soybean meal diets under simulated commercial grow-out conditions.

Two experiments, involving 5,760 birds each, were conducted under simulated commercial grow-out conditions to determine the relative response of broiler chicks to two supplemental levels each of DL-methionine (DL-MET), L-methionine (L-MET), and methionine hydroxy analogue-free acid (MHA-FA) fed on an equimolar basis in corn-soybean meal diets. MHA-FA was shown to support 49-day weight gains comparable to those of chicks fed DL-MET, and both sources were superior to L-MET in this regard. However, there were no significant differences due to MET sources in the efficiency of feed utilization. When compared to basal-fed chicks, birds fed supplemental L-MET, DL-MET, or MHA-FA had elevated plasma free MET levels, whereas cyst(e)ine and taurine concentrations were not affected by dietary treatment. There were no effects of diet on either mortality or the incidence of leg abnormalities. The results of these studies suggest that MHA-FA is an acceptable source of MET for broiler chicks fed corn-soybean meal diets from day-old to market weight.