Nitrogen partitioning and microbial protein synthesis in lactating dairy cows with different phenotypic residual feed intake

Table 4 Plasma variables of lactating cows selected for phenotypic divergence in residual feed intake (RFI)

Items^a	Low RFI	High RFI	SEM	P value^b
Items^a	Low RFI	High RFI	SEM	RFI	Day	RFI × Day
Protein metabolism
Total protein, g/L	70.8	71.8	0.99	0.51	0.75	0.39
Albumin (A), g/L	26.7	27.6	0.41	0.12	0.78	0.54
Globulin (G), g/L	44.2	44.2	1.02	0.99	0.81	0.51
A/G	0.61	0.63	0.02	0.39	0.92	0.69
BUN, mmol/L	5.63	6.23	0.31	0.18	0.21	0.18
Creatinine, μmol/L	74.9	72.2	2.27	0.38	0.17	0.43
Energy substrates
Glucose, mmol/L	3.61	3.48	0.09	0.35	0.42	0.61
NEFA, μmol/L	118	109	6.79	0.35	0.01	0.10
Triglyceride, μmol/L	0.17	0.28	0.04	0.09	0.75	0.95
Cholesterol, mmol/L	7.98	7.55	0.27	0.27	0.11	0.42
Liver function
ALT, U/L	26.2	28.3	0.80	0.08	0.27	0.71
AST, U/L	91.4	88.7	5.00	0.71	0.43	0.85
ALP, U/L	34.6	47.0	5.14	0.11	0.13	0.26
Total bilirubin, μmol/L	1.56	1.49	0.06	0.43	0.49	0.64

^aBUN blood urea nitrogen, NEFA nonesterified fatty acids, ALT alanine aminotransferase, AST aspartate aminotransferase, ALP alkaline phosphatase
^bP value associated with RFI, time, and the interaction of RFI and time

ISSN: 2049-1891