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.

BackgroundLimited availability of fish meal and whey protein concentrate increases overall feed costs. Availability of increased number of supplemental amino acids including Lys, Met, Thr, Trp, Val, and Ile allows replacing expensive protein supplements to reduce feed costs. This study was to evaluate the effect of replacing fish meal and/or whey protein concentrate in nursery diets with 6 supplemental amino acids on growth performance and gut health of post-weaning pigs. Treatments were 1) FM-WPC: diet with fish meal (FM) and whey protein concentrate (WPC); 2) FM-AA: diet with FM and crystalline amino acids (L-Lys, L-Thr, L-Trp, DL-Met, L-Val, and L-Ile); 3) WPC-AA: diet with WPC and crystalline amino acid; and 4) AA: diet with crystalline amino acid.ResultsPigs in FM-AA, WPC-AA, and AA had greater (P < 0.05) ADG and gain:feed than pigs in FM-WPC during wk 1 (phase 1). Plasma insulin concentration of pigs in AA tended to be greater (P = 0.064) than that of FM-WPC at the end of wk 1(phase 1). Plasma concentrations of IgG in AA was lower (P < 0.05) compared with WPC-AA and FW, and FM-AA had lower (P < 0.05) IgG concentration than WPC-AA at the end of wk 1 (phase 1). Concentration of acetate in cecum digesta in FM-AA tended to be greater (P = 0.054) than that of FM-WPC and WPC-AA. Concentration of isovalerate in cecum digesta of pigs in FM-AA was greater (P < 0.05) than that of FW and WPC-AA.ConclusionsThis study indicates that use of 6 supplemental amino acids can replace fish meal and/or whey protein concentrate without adverse effects on growth performance, immune status, and gut health of pigs at d 21 to 49 of age. Positive response with the use of 6 supplemental amino acids in growth during the first week of post-weaning may due to increased plasma insulin potentially improving uptake of nutrients for protein synthesis and energy utilization. The replacement of fish meal and/or whey protein concentrate with 6 supplemental amino acids could decrease the crude protein level in nursery diets, and potentially lead to substantial cost savings in expensive nursery diets.

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