The objective was to investigate if the plasma AA dose-response method,using total sulfur AA (TSAA) concentrations as a % of TAA – SAA concentrations,could statistically differentiate the metabolizable Met contentin 4 unique RP-Met products in lactating Holstein cows. Ten multiparousHolstein cows (175 ± 59 DIM) were used in a replicated 5 × 5 Latin squarewith 7-d experimental periods. The 5 treatments were: 1) a negative control(CON); 2) 24 g/d Met from Smartamine M (SMM; Adisseo; Met bioavailability≥80%); 3) 24 g/d Met from AminoShure-XM (AXM; Balchem);4) 24 g/d Met from MetiPEARL (MPL; Kemin); and 5) 24 g/d Metfrom Timet (TMT; Vetagro). Intake and milk yield were measured daily.Blood was collected from the tail vein the last 3 d per period at 2, 4, 6 and8 h after the 0500h feeding. Data were analyzed using MIXED and REGprocedures of SAS. Significance was declared at P ≤ 0.05. Milk yield(37.1 kg/d) and DMI (25.6 kg/d) were not affected by treatment. PlasmaMet, cystathionine/allocystathionine, and TSAA concentrations were increasedfor cows fed AXM compared with CON and MPL, and furtherincreased for SMM compared with AXM (Table 1; P < 0.001). Based oncomparison of dose-response slopes using TSAA expressed as a percentageof TAA-TSAA, AXM, MPL, and TMT were 35.0 (±4.0), 9.3 (±3.7),and 24.0% (±7.2) as effective as SMM in providing metabolizable Met.
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机译：目的是调查等离子体AA剂量 - 响应法，使用总硫AA（TSAA）浓度为TAA - SAA浓度的百分比，可以在统计上区分代谢的符合符合物在4个独特的RP-Met产品，哺乳期荷斯坦奶牛。十万多环霍尔斯坦奶牛（175±59昏暗）用于复制的5×5拉丁方形7-D实验期。 5种治疗是：1）阴性对照（符合）; 2）24 g / d由Smartamine M（SMM; Adisseo;满足生物利用度≥80％）; 3）24 g / d由aminoshure-xm（axm; balchem）满足;4）24 g / d由metipearl（mpl; kemin）达到;和5）24 g / d满足从时间表（TMT; vetagro）。每天测量摄入量和牛奶产量。从尾静脉收集血液，每次2,4,6和10500H喂养后8小时。使用混合和reg分析数据SAS的程序。在P≤0.05时声明意义。牛奶收益率（37.1 kg / d）和dmi（25.6kg / d）未受治疗的影响。等离子体达到，胱硫胺/类癌硫氨酸和TSAA浓度增加对于奶牛FED AXM与CON和MPL相比，进一步与AXM相比，SMM增加（表1; P <0.001）。基于使用TSAA表示为百分比的剂量 - 反应斜率的比较Taa-TSAA，AXM，MPL和TMT为35.0（±4.0），9.3（±3.7），和24.0％（±7.2）如SMM提供代谢符合的SMM。
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