Plasma metabolic profiling of dairy cows affected with clinical ketosis using LC/MS technology

Figures & data

Table 1. Characterization of both experimental groups (n = 10), namely group I suffering from clinical ketosis and group II being control cows.

	Group I	Group II
Age (years)	3.13 ± 1.31	3.59 ± 1.38
Parity (number)	1.56 ± 0.73	1.71 ± 0.95
Milk yield (kg/day)	18.86 ± 8.33	21.00 ± 4.25
Postpartum day	12.3 ± 4.5	16.0 ± 8.5
Glucose (mmol/L）	2.01 ± 0.33^A	3.12 ± 0.30
BHBA (mmol/L）	3.25 ± 1.48^A	0.66 ± 0.34
NEFA (mmol/L)	1.02 ± 0.65^A	0.34 ± 0.12

Note: Values are given as mean ± SD. Superscripts within a row represent significant differences (P < 0.05).

Figure 1. Total ion current (TIC) chromatograms of plasma samples from two groups of dairy cows: clinical ketosis (group I) and (group II). X-axis indicates the retention time (min); Y-axis indicates the control cows’ relative abundance of the mass response.

Figure 2. Principal component analysis (PCA) score plot of groups I and II.

Figure 3. Principal component analysis (PCA) score plot of groups I and II after the removal of outliers.

Figure 4. Orthogonal partial least-squares (OPLS) score plot of groups I and II.

Table 2. Metabolites in dairy cows with clinical ketosis as determined with LC/MS.

				I vs. II
No.	Compound	RT (min)	Frags (m/z)	VIP	P	FC
1	Arginine	0.61	203.052	1.42	2.12E−04	−1.23
2	Aminobutyric acid	0.66	104.107	0.83	4.08E−02	−0.56
3	Leucine/isoleucine^a	1.95	132.102	1.47	1.45E−02	−1.67
4	Tryptophan	7.66	205.097	1.06	7.39E−03	−0.88
5	Creatinine	7.87	114.091	1.48	1.16E−02	−0.72
6	Nicotine	10.03	163.132	1.55	2.78E−03	−0.76
7	Lysine	10.08	163.132	1.53	9.86E-03	−0.63
8	Undecanoic acid	10.92	187.225	1.53	6.64E−03	−0.69
9	Valine	6.56	160.097	1.46	7.23E−04	2.15
10	Glycine	9.75	206.081	1.56	3.33E−05	2.34
11	Glycocholic acid	11.74	466.316	1.10	1.24E−02	1.09
12	Tetradecenoic acid	19.04	227.201	1.18	9.34E−03	1.37
13	Palmitic acid	23.24	257.248	1.31	3.57E−03	0.79

Notes: RT (min): retention time of mass spectrometry and chromatography; Frags (m/z): mass-to-charge ratio; VIP: the first principal component with variable importance in projection (VIP) values in the orthogonal partial least-squares discriminant analysis (OPLS-DA) model, (threshold >1); P: significant difference between groups; FC: fold change, FC > 0, comparison between the two groups indicated, the former is higher than the latter.

^aThe structural isomers of leucine and isoleucine could not be separated with the current LC method.