Soaking and pelleting of pig diets alters the apparent absorption and retention of minerals

The effect of soaking a pig's diet in water (9 h at room temperature) or he at pelleting (81 degrees C) on apparent absorption and retention of intrins ic minerals was studied with and without the addition of calcium carbonate in a 2 x 3 factorial design. Thirty pigs were allocated to different diet t reatments and two separate balances were calculated throughout a 33-d study . Soaking the diet significantly (P < 0.001) reduced the phytate content (I P6) and increased (P < 0.001) the fractional content of degradation product s (IP3-5), whereas heat pelleting only marginally affected these compounds. Soaking and heat pelleting of feeds did not affect dry matter (DM) digesti bility or N and S balances in the animals (P > 0.85), indicating that feed matrix remained unaltered by the treatments. Dietary Ca addition reduced th e absorption coefficient of Dh I (P < 0.01), ash (P < 0.001) and Ca (P < 0. 05) as well as the uptake of P (P < 0.001). Heat pelleting selectively redu ced the uptake of feed Ca, Fe, Zn, Cu, and Mn compared with untreated and s oaked diets (P < 0.05). In conclusion, heat pelleting of feeds showed a neg ative effect on mineral uptake, whereas the soaking procedure seemed to hav e only a very marginal positive (P > 0.05) effect on the uptake of elements in the digestive tract.