The objective was to evaluate the association of serum Ca concentration and calcemic status with P, Mg, K, Na, Fe, Zn and Cu concentrations at calving on 768 multiparous Jersey cows from 2 commercial dairies. Blood samples for serum Ca, P, Mg, K, Na, Fe, Zn and Cu analyses were collected from the coccygeal vessels 3 h 14 min (±2 h 04 min) after calving. Serum samples were analyzed by Inductively Coupled Plasma – Optical Emission Spectrometry method (ICP-OES). Based on serum Ca concentration cows were classified as subclinical hypocalcemic (SCH; Ca ≤8.5 mg/dL; n = 518) and normocalcemic (NC; Ca >8.5 mg/dL; n = 250). Associations among variables and with calcemic status were analyzed using spearman rank correlations and mixed models, respectively (CORR and MIXED procedures of SAS). Descriptive statistics, including first (Q₁), second (Q₂) and third (Q₃) quartiles, of serum mineral concentrations at calving are shown in the Table 1. Serum Ca concentration was correlated negatively with Mg and positively with P, Na and Zn (P < 0.001; | r | > 0.15). Cows with SHC had higher serum Mg concentration than NC cows (2.53 vs. 2.42 mg/dL; P < 0.001) but lower P (3.84 vs. 4.77 mg/dL; P < 0.001), K (4.58 vs. 4.73 mEq/L; P = 0.01), Na (137.4 vs. 142.3 mEq/L; P < 0.001), Fe (1.00 vs. 1.11 ppm; P = 0.001), Zn (0.59 vs.0.69; P < 0.001) and Cu (0.80 vs. 0.86 ppm; P < 0.001). Our results suggest that the negative effects of postpartum subclinical hypocalcemia on dairy performance may be in some measure mediated by variations in other serum minerals. Table 1. Quartile distribution (Q₁ = 25th percentile, Q₂ = 50th percentile, Q₃ = 75th percentile) of serum mineral concentrations at calving

	Ca (mg/dL)	P(mg/dL)	Mg(mg/dL)	K(mEq/L)	Na(mEq/L)	Fe(ppm)	Zn(ppm)	Cu(ppm)
SCH
Q1	7.4	3.1	2.2	4.2	133	0.72	0.49	0.66
Q2	7.9	3.8	2.4	4.5	137	0.94	0.60	0.76
Q3	8.2	4.6	2.7	4.8	141	1.20	0.72	0.88
NC
Q1	8.8	4.0	2.2	4.4	139	0.79	0.60	0.71
Q2	8.9	4.8	2.4	4.6	142	1.00	0.69	0.81
Q3	9.2	5.6	2.5	4.9	145	1.30	0.80	0.95