Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny.

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.