THE EFFECTS OF SOW PARITY ON DIGESTIBILITY OF PROXIMATE COMPONENTS AND MINERALS DURING LACTATION AS INFLUENCED BY DIET AND MICROBIAL PHYTASE SUPPLEMENTATION

Ninety-six (Finnish Landrace Dutch Landrace) reproductive sows were us ed at parities 1, 3, 5, and 7 + 8 from d 107 of gestation to d 21 of l actation to investigate the effects of diet and parity on apparent tot al tract digestibility (ATTD). Animals were randomly assigned to one o f four dietary treatments. Dietary treatments were I) a P-deficient (1 .1 g digestible P [dP]/kg) Dutch semipractical diet; 2) Diet 1 supplem ented with 400 FTU Aspergillus niger phytase per kilogram of diet (1.7 g dP/kg); 3) a corn-soybean meal-based diet (1.3 g dP/kg); and 4) Die t 3 supplemented with extra monocalcium phosphate (MCP; 2.4 g dP/kg of diet). Animals were fed twice daily at 2.8 times maintenance (418 kJ ME/BW.75) from d 8 to the end of lactation. Feces and urine were colle cted during d 11 to 13 and d 18 to 20 of lactation. The ATTD of DM, OM , ash, CP, Ca, Mg, and total P (P < .01) were higher for the corn-soyb ean meal-based diets than for the Dutch semipractical diet not supplem ented with phytase. Addition of MCP enhanced total P ATTD by an averag e of 6.7 percentage units. Addition of microbial phytase improved Ca, Mg, and total P ATTD, but the effects were dependent on the stage of l actation. Lower ATTD of OM and CP were seen for first parity animals c ompared with higher parity sows. The ATTD of Mg increased with increas ing parity. Parity had little effect on the ATTD of minerals during la ctation, and dietary effects were prominent and followed a similar tre nd to those seen in growing-finishing pigs.