Zn status of sows and piglets as affected by diet and sow parity

• We evaluate if changes on dietary P, Ca and phytase and sow age affect milk Zn content.
• Milk Zn concentration is highly regulated and is difficult to visualize changes.
• Piglet Zn status is not conditioned to sows age or dietary changes during lactation.

The objective of the present study was to evaluate if changes to dietary P, Ca and phytase concentrations and sow parity number affect mineral transfer to piglets during lactation and productive and reproductive performance in sows. In experiment 1, sows (n=112) received the same gestation and lactation diets, and were grouped according to parity number. Colostrum and milk on d 21 of lactation were sampled from sows and analyzed for Zn, Fe and Cu. Hair from piglets was also collected at the 21st day of lactation and analyzed for Zn. In experiment 2, sows (41) were distributed into 3 groups based on parity and 4 dietary lactation treatments: dietary treatments were a lactation diet with recommended concentrations of Ca, P and Zn (Rec), a lactation with reduced concentrations of Ca, P and Zn (Low0), the Low diet supplemented with 250 FTU of phytase/kg feed (Low250), and the Low diet supplemented with 500 FTU of phytase/kg feed (Low500). Titanium dioxide (TiO2) was added as indigestible marker to all diets. Fecal samples were obtained between d 21 and 25 of lactation and analyzed for Ca, P, Zn, Fe, Cu and Ti. Blood and colostrum samples were obtained on day of farrowing, and blood and milk samples were collected on d 21, for Zn, Fe and Cu analysis. In experiment 1, no differences in trace minerals were observed between parity groups for colostrum, milk and hair except milk Cu concentrations were greater in older sows (6th–10th parity number) and milk Zn concentrations tended to be greater in older (6th–10th parity number) sows. In experiment 2, sows fed Rec had greater intake and excretion of Ca, P and Zn than the other three treatments. Sows supplemented with phytase (Low250 and Low500) had greater P digestibility than those without phytase (Rec and Low0). Zn, Fe and Cu concentrations in plasma and milk did not change with treatment. Parity did not alter any of the variables measured except plasma Cu levels, which were greater following farrowing in youngest sows. Large amounts of Zn are secreted in milk in relation to the body Zn stores during lactation. This research suggests the amount of Zn secreted by sows appears to be constant and independent of parity or phytase use in lactation diets low in P and Ca.