CHANGES IN APPARENT ABSORPTION AND RETENTION OF NUTRIENTS DURING GESTATION IN GILTS FED TWO DIETARY CALCIUM-PHOSPHORUS LEVELS

Twenty-seven Landrace × Yorkshire gilts were used in three trials to determine the influence of feeding more Ca-P from breeding through gestation on changes in apparent absorption and retention of energy, nitrogen, Ca, P, Mg, K, Mn, Cu and Zn, at the 5th, 8th, 11th, 13th and 15th wk of gestation. The gilts were housed during gestation in individual sow metabolism stalls equipped for separate collection of feces and urine. In trial 1, feeding more Ca-P (26.2–23.8 vs. 21.2–15.4 g d−1) during gestation reduced (P < 0.05) the percent absorption and retention of Ca, Mg, Zn and Cu at certain stages of gestation but the overall differences between the two diets were not significant. In trial 2 feeding more Ca-P (26.8–15.8 vs. 20.4–10.4 g d−1) also reduced the percent absorption and retention of Ca, Mg, Zn and Cu at certain stages of gestation and the overall differences between the two diets were not significant. In trial 3, feeding more Ca-P (23.6–18.2 vs. 17.8–12.4 g d−1) reduced the percent absorption and retention of energy, Ca, P, Mg, K, Zn, Mn and Cu at several stages of gestation and the overall differences between the two diets were significant for these nutrients. The percent absorption and retention of Ca, P and Mn progressively increased while that of nitrogen, K and Zn decreased with the advancement of gestation. The mineral levels of femurs and metacarpals of gilts and their piglets at birth were similar for both diets. The results indicated that feeding more Ca-P during gestation had minimal influence on amount of energy, nitrogen Ca and K absorption and retention but it increased the amount of P absorption and retention; however, the reduction of Zn, Mn and Cu absorption may cause deficiencies with inadequately supplemented diets. Key words: Gilt, gestation, minerals, energy, nitrogen, absorption, retention