Calcium, magnesium and phosphorus balance of sows during lactation for three parities

Abstract

The effects of two diets, differing by total phosphorus and calcium contents, on retention and excretion of Ca, P and Mg were studied in lactating sows. Mineral balances ( n=60) were measured during lactation (day 4 to 25) for three successive parities. Mineral retention in the litter was measured by chemical analysis of weaned piglets. The control diet (C) contained 7.2 g P, 9.4 g Ca and 2.6 g Mg kg −1 DM and the experimental diet (R) 6.5, 8.1, 2.5, respectively. Calculated digestible phosphorus level was 3.5 g kg −1 DM in both diets. Mean litter size was 10.4 piglets and mean litter gain was 2.7 kg d −1. Calcium, magnesium and phosphorus retentions in the piglets were not affected by dietary treatments. Mean retention in the sows was slightly negative for calcium and phosphorus, but positive for magnesium. Daily recommended allowances for lactating sows were 23.5 g digestible calcium and 16.5 g digestible phosphorus (both including a safety margin of 25%). Excretion of phosphorus in urine and faeces on diet R was 0.53 kg and on diet C 0.61 kg during a 25-day lactation. The possibilities for reducing phosphorus excretion during lactation are limited compared to those during pregnancy. Some reduction during lactation can be achieved by increasing phosphorus digestibility in the diet.