SELF-SELECTION OF SALT BY GILTS DURING PREGNANCY AND LACTATION

Abstract

There were two feeding experiments, in which feed was available free choice with 18 gilts in the first and 14 gilts in the second, and a metabolism trial, in which feed was restricted, with two pairs of gilts. Equal numbers of pregnant (P) and non-pregnant (NP) gilts were used; the terms "farrow" and "lactation" were applied to the NP gilts on a time basis only. In the first experiment and the 16-wk metabolism trial, a salt-deficient diet was fed, but in the second experiment the diet contained 0.5% added salt; all gilts had access to both water and a 0.5% salt solution. Considerable variation among gilts in both water and salt solution intake was evident, and there seemed to be a response to a taste preference rather than to a dietary need. During lactation, the intakes of salt solution and of total salt by the P gilts were approximately twice that of the NP gilts. Although consuming 78% more sodium from the salt solution, the P gilts did not lose in the feces and urine much more sodium than did the NP gilts; therefore, with equal feed intake, sodium retention appeared greater in the P gilts.