Effect of low dietary zinc supply during pregnancy and lactation on the sow and the neonatal piglet

Experiments were conducted with sows and littermate-gilts to investigate the effect of dietary zinc (Zn) restriction during either part or most of the pregnancy and lactation on dams and their offspring.Reduced dietary Zn (13 ppm) during the last 4 wk of pregnancy and first 2 wk of lactation presented no serious consequences to the dam or offspring. Reduction of dietary Zn throughout pregnancy and lactation (10 ppm) caused overt signs of Zn deficiency in one-half of the gilts, however, their offspring exhibited no obvious abnormalities. Zinc restriction did not affect feed consumption but depressed plasma and urinary Zn and plasma alkaline phosphatase activity (APA). The use of the balance technique and radiotracers revealed that gilts deficient in Zn initiated protective mechanisms such as, increased Zn absorption reduced endogenous Zn excretion, prolongation of the biological half life of Zn; all these responses affected higher efficiency of Zn utilization.Despite the protective mechanisms, gilts depleted in Zn exhibited prolonged stressful parturition and a high incidence of intrapartum and neonatal mortality than control gilts. Piglets from gilts depleted in Zn showed depressed birth weight, reduced concentrations of plasma Zn, Cu and ammonia and low APA and hematocrit, increased plasma concentrations of glucose and lactate, reduced content of Zn in liver, heart, lung, skin, bone and carcass and higher concentrations of Cu and Mn in various tissues compared to controls. Zinc depletion did not change the Zn content of colostrum but did change it in milk. Content of Cu, Fe, and Mn was effected in colostrum and milk. Weight of piglets was lower at one wk but not at two wk of age. Two-week old piglets exhibited lower Zn and higher Cu concentrations in plasma; reduced Zn and increased Cu and Mn concentrations in liver and bone and changes in Cu and Mn in other tissues. At the end of lactation, gilts depleted in Zn exhibited low level of Zn and APA in plasma; reduced Zn content in liver, spleen, heart, small intestine; increased Cu content in liver and small intestine; increased Zn and Mn content in brain.Although gilts depleted in Zn exhibited a highly efficient handling of Zn via homeostatic mechanisms, the reduced amount of corporal exchangeable Zn in these gilts caused biochemical changes affecting the performance of the dam and the offspring. (Abstract shortened with permission of author.