TABLE 2.

Blood plasma amino acid concentrations in Holstein cows individually fed a control diet or the control plus rumen-protected Met (0.9 g/kg dry matter intake) during the last 28 d before parturition. Temporal concentrations of His, Gln, Tyr, Asn, and total dispensable amino acids (Treat × Time, P < 0.05) and Pro (Treat × Time, P = 0.064) are reported in Figure 1¹

	Treatments		P value
Compound	Control	Met	Treat	Time	Treat × Time
Indispensable amino acids, μM
Ile	100 ± 5.8	107 ± 5.8	0.417	0.007	0.607
Leu	135 ± 6.5	140 ± 6.5	0.651	0.016	0.963
Lys	54.6 ± 2.4	58.8 ± 2.4	0.692	<0.001	0.643
Met	9.43 ± 0.76	12.0 ± 0.76	0.027	0.441	0.750
Phe	39.9 ± 1.2	39.7 ± 1.2	0.794	0.141	0.511
Thr	60.9 ± 2.7	58.7 ± 2.7	0.717	0.022	0.140
Val	213 ± 11.9	230 ± 11.9	0.339	0.001	0.937
Total	652 ± 25	679 ± 25	0.344	0.006	0.101
Met as % of total	1.54 ± 0.13	1.88 ± 0.13	0.114	0.003	0.983
Dispensable amino acids, μM
Ala	182 ± 8.8	178 ± 8.8	0.750	0.017	0.070
Arg	50.9 ± 2.0	49.7 ± 2.0	0.680	<0.001	0.218
Asp	9.59 ± 0.76	9.88 ± 0.76	0.793	0.007	0.842
Glu	39.1 ± 2.0	41.2 ± 2.0	0.483	0.003	0.623
Gly	297 ± 17.4	254 ± 17.4	0.095	<0.001	0.195
Ser	67.3 ± 3.2	63.9 ± 3.2	0.472	0.022	0.150
Tau	29.9 ± 0.6	24.7 ± 0.6	<0.001	0.980	0.512
BCAA, μM	448 ± 24	477 ± 24	0.424	0.003	0.903
Total indispensable + dispensable, μM	1652 ± 43	1631 ± 43	0.747	0.002	0.190
Met as % of total	0.58 ± 0.04	0.75 ± 0.04	0.014	0.011	0.932
Lys as % of total	5.76 ± 0.22	5.84 ± 0.22	0.811	<0.001	0.626
Other compounds, μM
α-Aminobutyric acid	16.6 ± 1.1	14.3 ± 1.1	0.053	<0.001	0.252
Ornithine	19.1 ± 1.7	19.4 ± 1.7	0.884	0.007	0.434
1-Methylhistidine	14.0 ± 0.9	12.0 ± 0.9	0.094	<0.001	0.353
3-Methylhistidine	5.57 ± 0.49	4.06 ± 0.49	0.050	<0.001	0.506

¹Values are means ± pooled SEMs, n = 10/treatment group. BCAA, branched-chain amino acid.