Table 6.

Effect of days postpartum on concentrations of mineral in the liver of postpartum beef cows at pasture turnout in year 2 of pasture treatment

	Days postpartum group1
Item, µg/g2	EARLY	MID	LATE	SE	P-value
Se	1.90x	1.77xy	1.67y	0.064	0.05
Cu	242.4	219.9	180.6	19.31	0.08
Zn	137.3	118.4	106.1	10.59	0.12
Mo	3.78	3.86	3.86	0.133	0.87
Mn	11.83	11.59	11.37	0.377	0.69
Co	0.236	0.232	0.255	0.015	0.56

¹Days postpartum (DPP): EARLY = 66.1; MID = 48.8; LATE = 34.5 ± 1.04 d. Days postpartum were calculated based on calving date in relation to pasture turn out. In year 2, three cows per pasture were selected for liver biopsy and represented each classification of DPP (EARLY, MID, or LATE) in order to evaluate the impact of DPP on mineral status.

²Mineral concentrations are reported in µg/g on a dry matter basis. Liver samples were analyzed for concentrations of Se, Cu, Zn, Mo, Mn, and Co via inductively coupled plasma mass spectrometry at the Diagnostic Center for Population and Animal Health at Michigan State University (East Lansing, M.I.).

^x,yMeans lacking common superscript differ (P ≤ 0.05).