Graded quantities of 1.38,2.76 and 4.14 g/kg L-methionine were included in a control diet formulated to contain 3.07 g/kg digestible methionine.Each of the 4 dietary treatments was offered to 6 replicate cages(initially 8 birds per cage)from 1 to 21 d post-hatch.The parameters assessed included growth per-formance,nutrient utilisation(apparent metabolizable energy[AME],AME:GE ratios,N retention,N-corrected apparent metabolizable energy[AMEn]),apparent digestibility coefficients and disappearance rates of amino acids in the distal ileum.They also included free amino concentrations in systemic plasma(brachial vein)at 20 d post-hatch and in hepatic tissue at 14 and 21 d post-hatch.Graded L-methionine inclusions quadratically influenced weight gain(r=0.688;P=0.001)and FCR(r=0.780;P＜0.001).It may be deduced from the quadratic regressions that 3.43 g/kg L-methionine supported maximum weight gain of 1,036 g/kg and 3.50 g/kg L-methionine minimum FCR of 1.193,from 1 to 21 d post-hatch.The control diet contained specified levels of 3.07 g/kg digestible methionine and 13.0 g/kg digestible lysine.Thus,an inclusion of 3.465 g/kg L-methionine corresponded to a total of 6.535 g/kg methionine or a methionine-to-lysine ratio of 50.3,which is higher than standard recommendations.The implications of this and other outcomes of the present study are reported and discussed.

Shemil P.Macelline;Peter V.Chrystal;Leon R.McQuade;Bernard V.Mclnerney;Yangsu Kim;Yumin Bao;Peter H.Selle;Sonia Y.Liu

Poultry Research Foundation,The University of Sydney,Camden,NSW,2570,Australia;School of Life and Environmental Sciences,Faculty of Science,The University of Sydney,Sydney,NSW 2006,Australia;Baiada Poultry Ltd,Pendle Hill,NSW 2145,Australia;Australian Proteome Analysis Facility,Macquarie University,Sydney,NSW,2109,Australia;CJ Bio,330,Dongho-ro,Jung-gu,Seoul,100-400,Republic of Korea;Redox Pty Ltd,Minto,NSW,2566,Australia;Sydney School of Veterinary Science,The University of Sydney,Camden,NSW,2570,Australia

动物营养（英文）

[1]Shemil P.Macelline;Peter V.Chrystal;Leon R.McQuade;Bernard V.Mclnerney;Yangsu Kim;Yumin Bao;Peter H.Selle;Sonia Y.Liu-.Graded methionine dietary inclusions influence growth performance and apparent ileal amino acid digestibility coefficients and disappearance rates in broiler chickens)[J].动物营养（英文）,2022(01):160-168

metabolizable,AMEn

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