Table 3.

Predicted and measured total liver vitamin A reserves (TLR), and ¹³C enrichment of lactating sow serum and liver retinol after 21 and 28 days of isotopic equilibration of a 20 μmol ¹³C₂-retinyl acetate dose.

	21-d timepoint		28-d timepoint (measured at death)
Sow	Serum-predicted TLR (µmol/g)	Milk-predicted TLR (µmol/g)	Measured TLRa (µmol/g)	Serum At%b	Liver At%b		Ratio
1	0.50	0.41	0.14	1.110	1.103		0.99
2c	0.67	0.52	–	1.114	–		–
3	0.49	0.46	0.34	1.112	1.111		1.00
4	3.81	2.99	0.18	1.087	1.083		1.00
5	0.25	0.23	0.10	1.124	1.116		0.99
6	1.89	0.83	0.37	1.093	1.088		1.00
Meand	1.27 ± 1.37e	0.91 ± 1.04e	0.23 ± 0.12	1.105 ± 0.015f	1.100 ± 0.014f		1.00 ± 0.01

At%: atom percent; TLR: total liver reserves of vitamin A.

^aDetermined by high pressure liquid chromatography.

^bDetermined by gas chromatography-combustion-isotope ratio mass spectrometry.

^cThe liver from sow 2 was missing at the point of supply and could not be analyzed.

^dValues are mean ± SD.

^eValues were not significantly different by paired sample t-test.

^fValues were not significantly different by paired sample t-test. Neither mean includes sow 2.